blob: 9d27c5fd9687a5d542f5fba80dd718182619a1a4 [file] [log] [blame]
<
From c844b2f5cfea185bcc5b5344ee642b3e3ee7ff03 Mon Sep 17 00:00:00 2001
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Mon, 28 Nov 2011 07:42:09 -0500
Subject: lttng lib: ring buffer
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
drivers/staging/lttng/lib/ringbuffer/api.h | 25 +
drivers/staging/lttng/lib/ringbuffer/backend.h | 250 +++
.../lttng/lib/ringbuffer/backend_internal.h | 449 +++++
.../staging/lttng/lib/ringbuffer/backend_types.h | 80 +
drivers/staging/lttng/lib/ringbuffer/config.h | 298 ++++
drivers/staging/lttng/lib/ringbuffer/frontend.h | 228 +++
.../staging/lttng/lib/ringbuffer/frontend_api.h | 358 ++++
.../lttng/lib/ringbuffer/frontend_internal.h | 424 +++++
.../staging/lttng/lib/ringbuffer/frontend_types.h | 176 ++
drivers/staging/lttng/lib/ringbuffer/iterator.h | 70 +
drivers/staging/lttng/lib/ringbuffer/nohz.h | 30 +
.../lttng/lib/ringbuffer/ring_buffer_backend.c | 854 ++++++++++
.../lttng/lib/ringbuffer/ring_buffer_frontend.c | 1721 ++++++++++++++++++++
.../lttng/lib/ringbuffer/ring_buffer_iterator.c | 798 +++++++++
.../lttng/lib/ringbuffer/ring_buffer_mmap.c | 115 ++
.../lttng/lib/ringbuffer/ring_buffer_splice.c | 202 +++
.../staging/lttng/lib/ringbuffer/ring_buffer_vfs.c | 387 +++++
drivers/staging/lttng/lib/ringbuffer/vatomic.h | 85 +
drivers/staging/lttng/lib/ringbuffer/vfs.h | 89 +
19 files changed, 6639 insertions(+), 0 deletions(-)
create mode 100644 drivers/staging/lttng/lib/ringbuffer/api.h
create mode 100644 drivers/staging/lttng/lib/ringbuffer/backend.h
create mode 100644 drivers/staging/lttng/lib/ringbuffer/backend_internal.h
create mode 100644 drivers/staging/lttng/lib/ringbuffer/backend_types.h
create mode 100644 drivers/staging/lttng/lib/ringbuffer/config.h
create mode 100644 drivers/staging/lttng/lib/ringbuffer/frontend.h
create mode 100644 drivers/staging/lttng/lib/ringbuffer/frontend_api.h
create mode 100644 drivers/staging/lttng/lib/ringbuffer/frontend_internal.h
create mode 100644 drivers/staging/lttng/lib/ringbuffer/frontend_types.h
create mode 100644 drivers/staging/lttng/lib/ringbuffer/iterator.h
create mode 100644 drivers/staging/lttng/lib/ringbuffer/nohz.h
create mode 100644 drivers/staging/lttng/lib/ringbuffer/ring_buffer_backend.c
create mode 100644 drivers/staging/lttng/lib/ringbuffer/ring_buffer_frontend.c
create mode 100644 drivers/staging/lttng/lib/ringbuffer/ring_buffer_iterator.c
create mode 100644 drivers/staging/lttng/lib/ringbuffer/ring_buffer_mmap.c
create mode 100644 drivers/staging/lttng/lib/ringbuffer/ring_buffer_splice.c
create mode 100644 drivers/staging/lttng/lib/ringbuffer/ring_buffer_vfs.c
create mode 100644 drivers/staging/lttng/lib/ringbuffer/vatomic.h
create mode 100644 drivers/staging/lttng/lib/ringbuffer/vfs.h
diff --git a/drivers/staging/lttng/lib/ringbuffer/api.h b/drivers/staging/lttng/lib/ringbuffer/api.h
new file mode 100644
index 0000000..f8a1145
--- /dev/null
+++ b/drivers/staging/lttng/lib/ringbuffer/api.h
@@ -0,0 +1,25 @@
+#ifndef _LINUX_RING_BUFFER_API_H
+#define _LINUX_RING_BUFFER_API_H
+
+/*
+ * linux/ringbuffer/api.h
+ *
+ * Copyright (C) 2010 - Mathieu Desnoyers "mathieu.desnoyers@efficios.com"
+ *
+ * Ring Buffer API.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include "../../wrapper/ringbuffer/backend.h"
+#include "../../wrapper/ringbuffer/frontend.h"
+#include "../../wrapper/ringbuffer/vfs.h"
+
+/*
+ * ring_buffer_frontend_api.h contains static inline functions that depend on
+ * client static inlines. Hence the inclusion of this "api" header only
+ * within the client.
+ */
+#include "../../wrapper/ringbuffer/frontend_api.h"
+
+#endif /* _LINUX_RING_BUFFER_API_H */
diff --git a/drivers/staging/lttng/lib/ringbuffer/backend.h b/drivers/staging/lttng/lib/ringbuffer/backend.h
new file mode 100644
index 0000000..541dc53
--- /dev/null
+++ b/drivers/staging/lttng/lib/ringbuffer/backend.h
@@ -0,0 +1,250 @@
+#ifndef _LINUX_RING_BUFFER_BACKEND_H
+#define _LINUX_RING_BUFFER_BACKEND_H
+
+/*
+ * linux/ringbuffer/backend.h
+ *
+ * Copyright (C) 2008-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Ring buffer backend (API).
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ *
+ * Credits to Steven Rostedt for proposing to use an extra-subbuffer owned by
+ * the reader in flight recorder mode.
+ */
+
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/timer.h>
+#include <linux/wait.h>
+#include <linux/poll.h>
+#include <linux/list.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+
+/* Internal helpers */
+#include "../../wrapper/ringbuffer/backend_internal.h"
+#include "../../wrapper/ringbuffer/frontend_internal.h"
+
+/* Ring buffer backend API */
+
+/* Ring buffer backend access (read/write) */
+
+extern size_t lib_ring_buffer_read(struct lib_ring_buffer_backend *bufb,
+ size_t offset, void *dest, size_t len);
+
+extern int __lib_ring_buffer_copy_to_user(struct lib_ring_buffer_backend *bufb,
+ size_t offset, void __user *dest,
+ size_t len);
+
+extern int lib_ring_buffer_read_cstr(struct lib_ring_buffer_backend *bufb,
+ size_t offset, void *dest, size_t len);
+
+extern struct page **
+lib_ring_buffer_read_get_page(struct lib_ring_buffer_backend *bufb, size_t offset,
+ void ***virt);
+
+/*
+ * Return the address where a given offset is located.
+ * Should be used to get the current subbuffer header pointer. Given we know
+ * it's never on a page boundary, it's safe to write directly to this address,
+ * as long as the write is never bigger than a page size.
+ */
+extern void *
+lib_ring_buffer_offset_address(struct lib_ring_buffer_backend *bufb,
+ size_t offset);
+extern void *
+lib_ring_buffer_read_offset_address(struct lib_ring_buffer_backend *bufb,
+ size_t offset);
+
+/**
+ * lib_ring_buffer_write - write data to a buffer backend
+ * @config : ring buffer instance configuration
+ * @ctx: ring buffer context. (input arguments only)
+ * @src : source pointer to copy from
+ * @len : length of data to copy
+ *
+ * This function copies "len" bytes of data from a source pointer to a buffer
+ * backend, at the current context offset. This is more or less a buffer
+ * backend-specific memcpy() operation. Calls the slow path (_ring_buffer_write)
+ * if copy is crossing a page boundary.
+ */
+static inline
+void lib_ring_buffer_write(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_ctx *ctx,
+ const void *src, size_t len)
+{
+ struct lib_ring_buffer_backend *bufb = &ctx->buf->backend;
+ struct channel_backend *chanb = &ctx->chan->backend;
+ size_t sbidx, index;
+ size_t offset = ctx->buf_offset;
+ ssize_t pagecpy;
+ struct lib_ring_buffer_backend_pages *rpages;
+ unsigned long sb_bindex, id;
+
+ offset &= chanb->buf_size - 1;
+ sbidx = offset >> chanb->subbuf_size_order;
+ index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
+ pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK);
+ id = bufb->buf_wsb[sbidx].id;
+ sb_bindex = subbuffer_id_get_index(config, id);
+ rpages = bufb->array[sb_bindex];
+ CHAN_WARN_ON(ctx->chan,
+ config->mode == RING_BUFFER_OVERWRITE
+ && subbuffer_id_is_noref(config, id));
+ if (likely(pagecpy == len))
+ lib_ring_buffer_do_copy(config,
+ rpages->p[index].virt
+ + (offset & ~PAGE_MASK),
+ src, len);
+ else
+ _lib_ring_buffer_write(bufb, offset, src, len, 0);
+ ctx->buf_offset += len;
+}
+
+/**
+ * lib_ring_buffer_memset - write len bytes of c to a buffer backend
+ * @config : ring buffer instance configuration
+ * @bufb : ring buffer backend
+ * @offset : offset within the buffer
+ * @c : the byte to copy
+ * @len : number of bytes to copy
+ *
+ * This function writes "len" bytes of "c" to a buffer backend, at a specific
+ * offset. This is more or less a buffer backend-specific memset() operation.
+ * Calls the slow path (_ring_buffer_memset) if write is crossing a page
+ * boundary.
+ */
+static inline
+void lib_ring_buffer_memset(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_ctx *ctx, int c, size_t len)
+{
+
+ struct lib_ring_buffer_backend *bufb = &ctx->buf->backend;
+ struct channel_backend *chanb = &ctx->chan->backend;
+ size_t sbidx, index;
+ size_t offset = ctx->buf_offset;
+ ssize_t pagecpy;
+ struct lib_ring_buffer_backend_pages *rpages;
+ unsigned long sb_bindex, id;
+
+ offset &= chanb->buf_size - 1;
+ sbidx = offset >> chanb->subbuf_size_order;
+ index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
+ pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK);
+ id = bufb->buf_wsb[sbidx].id;
+ sb_bindex = subbuffer_id_get_index(config, id);
+ rpages = bufb->array[sb_bindex];
+ CHAN_WARN_ON(ctx->chan,
+ config->mode == RING_BUFFER_OVERWRITE
+ && subbuffer_id_is_noref(config, id));
+ if (likely(pagecpy == len))
+ lib_ring_buffer_do_memset(rpages->p[index].virt
+ + (offset & ~PAGE_MASK),
+ c, len);
+ else
+ _lib_ring_buffer_memset(bufb, offset, c, len, 0);
+ ctx->buf_offset += len;
+}
+
+/**
+ * lib_ring_buffer_copy_from_user - write userspace data to a buffer backend
+ * @config : ring buffer instance configuration
+ * @ctx: ring buffer context. (input arguments only)
+ * @src : userspace source pointer to copy from
+ * @len : length of data to copy
+ *
+ * This function copies "len" bytes of data from a userspace pointer to a
+ * buffer backend, at the current context offset. This is more or less a buffer
+ * backend-specific memcpy() operation. Calls the slow path
+ * (_ring_buffer_write_from_user) if copy is crossing a page boundary.
+ */
+static inline
+void lib_ring_buffer_copy_from_user(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_ctx *ctx,
+ const void __user *src, size_t len)
+{
+ struct lib_ring_buffer_backend *bufb = &ctx->buf->backend;
+ struct channel_backend *chanb = &ctx->chan->backend;
+ size_t sbidx, index;
+ size_t offset = ctx->buf_offset;
+ ssize_t pagecpy;
+ struct lib_ring_buffer_backend_pages *rpages;
+ unsigned long sb_bindex, id;
+ unsigned long ret;
+
+ offset &= chanb->buf_size - 1;
+ sbidx = offset >> chanb->subbuf_size_order;
+ index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
+ pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK);
+ id = bufb->buf_wsb[sbidx].id;
+ sb_bindex = subbuffer_id_get_index(config, id);
+ rpages = bufb->array[sb_bindex];
+ CHAN_WARN_ON(ctx->chan,
+ config->mode == RING_BUFFER_OVERWRITE
+ && subbuffer_id_is_noref(config, id));
+
+ if (unlikely(!access_ok(VERIFY_READ, src, len)))
+ goto fill_buffer;
+
+ if (likely(pagecpy == len)) {
+ ret = lib_ring_buffer_do_copy_from_user(
+ rpages->p[index].virt + (offset & ~PAGE_MASK),
+ src, len);
+ if (unlikely(ret > 0)) {
+ len -= (pagecpy - ret);
+ offset += (pagecpy - ret);
+ goto fill_buffer;
+ }
+ } else {
+ _lib_ring_buffer_copy_from_user(bufb, offset, src, len, 0);
+ }
+ ctx->buf_offset += len;
+
+ return;
+
+fill_buffer:
+ /*
+ * In the error path we call the slow path version to avoid
+ * the pollution of static inline code.
+ */
+ _lib_ring_buffer_memset(bufb, offset, 0, len, 0);
+}
+
+/*
+ * This accessor counts the number of unread records in a buffer.
+ * It only provides a consistent value if no reads not writes are performed
+ * concurrently.
+ */
+static inline
+unsigned long lib_ring_buffer_get_records_unread(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ struct lib_ring_buffer_backend *bufb = &buf->backend;
+ struct lib_ring_buffer_backend_pages *pages;
+ unsigned long records_unread = 0, sb_bindex, id;
+ unsigned int i;
+
+ for (i = 0; i < bufb->chan->backend.num_subbuf; i++) {
+ id = bufb->buf_wsb[i].id;
+ sb_bindex = subbuffer_id_get_index(config, id);
+ pages = bufb->array[sb_bindex];
+ records_unread += v_read(config, &pages->records_unread);
+ }
+ if (config->mode == RING_BUFFER_OVERWRITE) {
+ id = bufb->buf_rsb.id;
+ sb_bindex = subbuffer_id_get_index(config, id);
+ pages = bufb->array[sb_bindex];
+ records_unread += v_read(config, &pages->records_unread);
+ }
+ return records_unread;
+}
+
+ssize_t lib_ring_buffer_file_splice_read(struct file *in, loff_t *ppos,
+ struct pipe_inode_info *pipe,
+ size_t len, unsigned int flags);
+loff_t lib_ring_buffer_no_llseek(struct file *file, loff_t offset, int origin);
+
+#endif /* _LINUX_RING_BUFFER_BACKEND_H */
diff --git a/drivers/staging/lttng/lib/ringbuffer/backend_internal.h b/drivers/staging/lttng/lib/ringbuffer/backend_internal.h
new file mode 100644
index 0000000..442f357
--- /dev/null
+++ b/drivers/staging/lttng/lib/ringbuffer/backend_internal.h
@@ -0,0 +1,449 @@
+#ifndef _LINUX_RING_BUFFER_BACKEND_INTERNAL_H
+#define _LINUX_RING_BUFFER_BACKEND_INTERNAL_H
+
+/*
+ * linux/ringbuffer/backend_internal.h
+ *
+ * Copyright (C) 2008-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Ring buffer backend (internal helpers).
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include "../../wrapper/ringbuffer/config.h"
+#include "../../wrapper/ringbuffer/backend_types.h"
+#include "../../wrapper/ringbuffer/frontend_types.h"
+#include <linux/string.h>
+#include <linux/uaccess.h>
+
+/* Ring buffer backend API presented to the frontend */
+
+/* Ring buffer and channel backend create/free */
+
+int lib_ring_buffer_backend_create(struct lib_ring_buffer_backend *bufb,
+ struct channel_backend *chan, int cpu);
+void channel_backend_unregister_notifiers(struct channel_backend *chanb);
+void lib_ring_buffer_backend_free(struct lib_ring_buffer_backend *bufb);
+int channel_backend_init(struct channel_backend *chanb,
+ const char *name,
+ const struct lib_ring_buffer_config *config,
+ void *priv, size_t subbuf_size,
+ size_t num_subbuf);
+void channel_backend_free(struct channel_backend *chanb);
+
+void lib_ring_buffer_backend_reset(struct lib_ring_buffer_backend *bufb);
+void channel_backend_reset(struct channel_backend *chanb);
+
+int lib_ring_buffer_backend_init(void);
+void lib_ring_buffer_backend_exit(void);
+
+extern void _lib_ring_buffer_write(struct lib_ring_buffer_backend *bufb,
+ size_t offset, const void *src, size_t len,
+ ssize_t pagecpy);
+extern void _lib_ring_buffer_memset(struct lib_ring_buffer_backend *bufb,
+ size_t offset, int c, size_t len,
+ ssize_t pagecpy);
+extern void _lib_ring_buffer_copy_from_user(struct lib_ring_buffer_backend *bufb,
+ size_t offset, const void *src,
+ size_t len, ssize_t pagecpy);
+
+/*
+ * Subbuffer ID bits for overwrite mode. Need to fit within a single word to be
+ * exchanged atomically.
+ *
+ * Top half word, except lowest bit, belongs to "offset", which is used to keep
+ * to count the produced buffers. For overwrite mode, this provides the
+ * consumer with the capacity to read subbuffers in order, handling the
+ * situation where producers would write up to 2^15 buffers (or 2^31 for 64-bit
+ * systems) concurrently with a single execution of get_subbuf (between offset
+ * sampling and subbuffer ID exchange).
+ */
+
+#define HALF_ULONG_BITS (BITS_PER_LONG >> 1)
+
+#define SB_ID_OFFSET_SHIFT (HALF_ULONG_BITS + 1)
+#define SB_ID_OFFSET_COUNT (1UL << SB_ID_OFFSET_SHIFT)
+#define SB_ID_OFFSET_MASK (~(SB_ID_OFFSET_COUNT - 1))
+/*
+ * Lowest bit of top word half belongs to noref. Used only for overwrite mode.
+ */
+#define SB_ID_NOREF_SHIFT (SB_ID_OFFSET_SHIFT - 1)
+#define SB_ID_NOREF_COUNT (1UL << SB_ID_NOREF_SHIFT)
+#define SB_ID_NOREF_MASK SB_ID_NOREF_COUNT
+/*
+ * In overwrite mode: lowest half of word is used for index.
+ * Limit of 2^16 subbuffers per buffer on 32-bit, 2^32 on 64-bit.
+ * In producer-consumer mode: whole word used for index.
+ */
+#define SB_ID_INDEX_SHIFT 0
+#define SB_ID_INDEX_COUNT (1UL << SB_ID_INDEX_SHIFT)
+#define SB_ID_INDEX_MASK (SB_ID_NOREF_COUNT - 1)
+
+/*
+ * Construct the subbuffer id from offset, index and noref. Use only the index
+ * for producer-consumer mode (offset and noref are only used in overwrite
+ * mode).
+ */
+static inline
+unsigned long subbuffer_id(const struct lib_ring_buffer_config *config,
+ unsigned long offset, unsigned long noref,
+ unsigned long index)
+{
+ if (config->mode == RING_BUFFER_OVERWRITE)
+ return (offset << SB_ID_OFFSET_SHIFT)
+ | (noref << SB_ID_NOREF_SHIFT)
+ | index;
+ else
+ return index;
+}
+
+/*
+ * Compare offset with the offset contained within id. Return 1 if the offset
+ * bits are identical, else 0.
+ */
+static inline
+int subbuffer_id_compare_offset(const struct lib_ring_buffer_config *config,
+ unsigned long id, unsigned long offset)
+{
+ return (id & SB_ID_OFFSET_MASK) == (offset << SB_ID_OFFSET_SHIFT);
+}
+
+static inline
+unsigned long subbuffer_id_get_index(const struct lib_ring_buffer_config *config,
+ unsigned long id)
+{
+ if (config->mode == RING_BUFFER_OVERWRITE)
+ return id & SB_ID_INDEX_MASK;
+ else
+ return id;
+}
+
+static inline
+unsigned long subbuffer_id_is_noref(const struct lib_ring_buffer_config *config,
+ unsigned long id)
+{
+ if (config->mode == RING_BUFFER_OVERWRITE)
+ return !!(id & SB_ID_NOREF_MASK);
+ else
+ return 1;
+}
+
+/*
+ * Only used by reader on subbuffer ID it has exclusive access to. No volatile
+ * needed.
+ */
+static inline
+void subbuffer_id_set_noref(const struct lib_ring_buffer_config *config,
+ unsigned long *id)
+{
+ if (config->mode == RING_BUFFER_OVERWRITE)
+ *id |= SB_ID_NOREF_MASK;
+}
+
+static inline
+void subbuffer_id_set_noref_offset(const struct lib_ring_buffer_config *config,
+ unsigned long *id, unsigned long offset)
+{
+ unsigned long tmp;
+
+ if (config->mode == RING_BUFFER_OVERWRITE) {
+ tmp = *id;
+ tmp &= ~SB_ID_OFFSET_MASK;
+ tmp |= offset << SB_ID_OFFSET_SHIFT;
+ tmp |= SB_ID_NOREF_MASK;
+ /* Volatile store, read concurrently by readers. */
+ ACCESS_ONCE(*id) = tmp;
+ }
+}
+
+/* No volatile access, since already used locally */
+static inline
+void subbuffer_id_clear_noref(const struct lib_ring_buffer_config *config,
+ unsigned long *id)
+{
+ if (config->mode == RING_BUFFER_OVERWRITE)
+ *id &= ~SB_ID_NOREF_MASK;
+}
+
+/*
+ * For overwrite mode, cap the number of subbuffers per buffer to:
+ * 2^16 on 32-bit architectures
+ * 2^32 on 64-bit architectures
+ * This is required to fit in the index part of the ID. Return 0 on success,
+ * -EPERM on failure.
+ */
+static inline
+int subbuffer_id_check_index(const struct lib_ring_buffer_config *config,
+ unsigned long num_subbuf)
+{
+ if (config->mode == RING_BUFFER_OVERWRITE)
+ return (num_subbuf > (1UL << HALF_ULONG_BITS)) ? -EPERM : 0;
+ else
+ return 0;
+}
+
+static inline
+void subbuffer_count_record(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_backend *bufb,
+ unsigned long idx)
+{
+ unsigned long sb_bindex;
+
+ sb_bindex = subbuffer_id_get_index(config, bufb->buf_wsb[idx].id);
+ v_inc(config, &bufb->array[sb_bindex]->records_commit);
+}
+
+/*
+ * Reader has exclusive subbuffer access for record consumption. No need to
+ * perform the decrement atomically.
+ */
+static inline
+void subbuffer_consume_record(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_backend *bufb)
+{
+ unsigned long sb_bindex;
+
+ sb_bindex = subbuffer_id_get_index(config, bufb->buf_rsb.id);
+ CHAN_WARN_ON(bufb->chan,
+ !v_read(config, &bufb->array[sb_bindex]->records_unread));
+ /* Non-atomic decrement protected by exclusive subbuffer access */
+ _v_dec(config, &bufb->array[sb_bindex]->records_unread);
+ v_inc(config, &bufb->records_read);
+}
+
+static inline
+unsigned long subbuffer_get_records_count(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_backend *bufb,
+ unsigned long idx)
+{
+ unsigned long sb_bindex;
+
+ sb_bindex = subbuffer_id_get_index(config, bufb->buf_wsb[idx].id);
+ return v_read(config, &bufb->array[sb_bindex]->records_commit);
+}
+
+/*
+ * Must be executed at subbuffer delivery when the writer has _exclusive_
+ * subbuffer access. See ring_buffer_check_deliver() for details.
+ * ring_buffer_get_records_count() must be called to get the records count
+ * before this function, because it resets the records_commit count.
+ */
+static inline
+unsigned long subbuffer_count_records_overrun(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_backend *bufb,
+ unsigned long idx)
+{
+ struct lib_ring_buffer_backend_pages *pages;
+ unsigned long overruns, sb_bindex;
+
+ sb_bindex = subbuffer_id_get_index(config, bufb->buf_wsb[idx].id);
+ pages = bufb->array[sb_bindex];
+ overruns = v_read(config, &pages->records_unread);
+ v_set(config, &pages->records_unread,
+ v_read(config, &pages->records_commit));
+ v_set(config, &pages->records_commit, 0);
+
+ return overruns;
+}
+
+static inline
+void subbuffer_set_data_size(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_backend *bufb,
+ unsigned long idx,
+ unsigned long data_size)
+{
+ struct lib_ring_buffer_backend_pages *pages;
+ unsigned long sb_bindex;
+
+ sb_bindex = subbuffer_id_get_index(config, bufb->buf_wsb[idx].id);
+ pages = bufb->array[sb_bindex];
+ pages->data_size = data_size;
+}
+
+static inline
+unsigned long subbuffer_get_read_data_size(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_backend *bufb)
+{
+ struct lib_ring_buffer_backend_pages *pages;
+ unsigned long sb_bindex;
+
+ sb_bindex = subbuffer_id_get_index(config, bufb->buf_rsb.id);
+ pages = bufb->array[sb_bindex];
+ return pages->data_size;
+}
+
+static inline
+unsigned long subbuffer_get_data_size(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_backend *bufb,
+ unsigned long idx)
+{
+ struct lib_ring_buffer_backend_pages *pages;
+ unsigned long sb_bindex;
+
+ sb_bindex = subbuffer_id_get_index(config, bufb->buf_wsb[idx].id);
+ pages = bufb->array[sb_bindex];
+ return pages->data_size;
+}
+
+/**
+ * lib_ring_buffer_clear_noref - Clear the noref subbuffer flag, called by
+ * writer.
+ */
+static inline
+void lib_ring_buffer_clear_noref(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_backend *bufb,
+ unsigned long idx)
+{
+ unsigned long id, new_id;
+
+ if (config->mode != RING_BUFFER_OVERWRITE)
+ return;
+
+ /*
+ * Performing a volatile access to read the sb_pages, because we want to
+ * read a coherent version of the pointer and the associated noref flag.
+ */
+ id = ACCESS_ONCE(bufb->buf_wsb[idx].id);
+ for (;;) {
+ /* This check is called on the fast path for each record. */
+ if (likely(!subbuffer_id_is_noref(config, id))) {
+ /*
+ * Store after load dependency ordering the writes to
+ * the subbuffer after load and test of the noref flag
+ * matches the memory barrier implied by the cmpxchg()
+ * in update_read_sb_index().
+ */
+ return; /* Already writing to this buffer */
+ }
+ new_id = id;
+ subbuffer_id_clear_noref(config, &new_id);
+ new_id = cmpxchg(&bufb->buf_wsb[idx].id, id, new_id);
+ if (likely(new_id == id))
+ break;
+ id = new_id;
+ }
+}
+
+/**
+ * lib_ring_buffer_set_noref_offset - Set the noref subbuffer flag and offset,
+ * called by writer.
+ */
+static inline
+void lib_ring_buffer_set_noref_offset(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_backend *bufb,
+ unsigned long idx, unsigned long offset)
+{
+ if (config->mode != RING_BUFFER_OVERWRITE)
+ return;
+
+ /*
+ * Because ring_buffer_set_noref() is only called by a single thread
+ * (the one which updated the cc_sb value), there are no concurrent
+ * updates to take care of: other writers have not updated cc_sb, so
+ * they cannot set the noref flag, and concurrent readers cannot modify
+ * the pointer because the noref flag is not set yet.
+ * The smp_wmb() in ring_buffer_commit() takes care of ordering writes
+ * to the subbuffer before this set noref operation.
+ * subbuffer_set_noref() uses a volatile store to deal with concurrent
+ * readers of the noref flag.
+ */
+ CHAN_WARN_ON(bufb->chan,
+ subbuffer_id_is_noref(config, bufb->buf_wsb[idx].id));
+ /*
+ * Memory barrier that ensures counter stores are ordered before set
+ * noref and offset.
+ */
+ smp_mb();
+ subbuffer_id_set_noref_offset(config, &bufb->buf_wsb[idx].id, offset);
+}
+
+/**
+ * update_read_sb_index - Read-side subbuffer index update.
+ */
+static inline
+int update_read_sb_index(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_backend *bufb,
+ struct channel_backend *chanb,
+ unsigned long consumed_idx,
+ unsigned long consumed_count)
+{
+ unsigned long old_id, new_id;
+
+ if (config->mode == RING_BUFFER_OVERWRITE) {
+ /*
+ * Exchange the target writer subbuffer with our own unused
+ * subbuffer. No need to use ACCESS_ONCE() here to read the
+ * old_wpage, because the value read will be confirmed by the
+ * following cmpxchg().
+ */
+ old_id = bufb->buf_wsb[consumed_idx].id;
+ if (unlikely(!subbuffer_id_is_noref(config, old_id)))
+ return -EAGAIN;
+ /*
+ * Make sure the offset count we are expecting matches the one
+ * indicated by the writer.
+ */
+ if (unlikely(!subbuffer_id_compare_offset(config, old_id,
+ consumed_count)))
+ return -EAGAIN;
+ CHAN_WARN_ON(bufb->chan,
+ !subbuffer_id_is_noref(config, bufb->buf_rsb.id));
+ subbuffer_id_set_noref_offset(config, &bufb->buf_rsb.id,
+ consumed_count);
+ new_id = cmpxchg(&bufb->buf_wsb[consumed_idx].id, old_id,
+ bufb->buf_rsb.id);
+ if (unlikely(old_id != new_id))
+ return -EAGAIN;
+ bufb->buf_rsb.id = new_id;
+ } else {
+ /* No page exchange, use the writer page directly */
+ bufb->buf_rsb.id = bufb->buf_wsb[consumed_idx].id;
+ }
+ return 0;
+}
+
+/*
+ * Use the architecture-specific memcpy implementation for constant-sized
+ * inputs, but rely on an inline memcpy for length statically unknown.
+ * The function call to memcpy is just way too expensive for a fast path.
+ */
+#define lib_ring_buffer_do_copy(config, dest, src, len) \
+do { \
+ size_t __len = (len); \
+ if (__builtin_constant_p(len)) \
+ memcpy(dest, src, __len); \
+ else \
+ inline_memcpy(dest, src, __len); \
+} while (0)
+
+/*
+ * We use __copy_from_user to copy userspace data since we already
+ * did the access_ok for the whole range.
+ */
+static inline
+unsigned long lib_ring_buffer_do_copy_from_user(void *dest,
+ const void __user *src,
+ unsigned long len)
+{
+ return __copy_from_user(dest, src, len);
+}
+
+/*
+ * write len bytes to dest with c
+ */
+static inline
+void lib_ring_buffer_do_memset(char *dest, int c,
+ unsigned long len)
+{
+ unsigned long i;
+
+ for (i = 0; i < len; i++)
+ dest[i] = c;
+}
+
+#endif /* _LINUX_RING_BUFFER_BACKEND_INTERNAL_H */
diff --git a/drivers/staging/lttng/lib/ringbuffer/backend_types.h b/drivers/staging/lttng/lib/ringbuffer/backend_types.h
new file mode 100644
index 0000000..1d301de
--- /dev/null
+++ b/drivers/staging/lttng/lib/ringbuffer/backend_types.h
@@ -0,0 +1,80 @@
+#ifndef _LINUX_RING_BUFFER_BACKEND_TYPES_H
+#define _LINUX_RING_BUFFER_BACKEND_TYPES_H
+
+/*
+ * linux/ringbuffer/backend_types.h
+ *
+ * Copyright (C) 2008-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Ring buffer backend (types).
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/cpumask.h>
+#include <linux/types.h>
+
+struct lib_ring_buffer_backend_page {
+ void *virt; /* page virtual address (cached) */
+ struct page *page; /* pointer to page structure */
+};
+
+struct lib_ring_buffer_backend_pages {
+ unsigned long mmap_offset; /* offset of the subbuffer in mmap */
+ union v_atomic records_commit; /* current records committed count */
+ union v_atomic records_unread; /* records to read */
+ unsigned long data_size; /* Amount of data to read from subbuf */
+ struct lib_ring_buffer_backend_page p[];
+};
+
+struct lib_ring_buffer_backend_subbuffer {
+ /* Identifier for subbuf backend pages. Exchanged atomically. */
+ unsigned long id; /* backend subbuffer identifier */
+};
+
+/*
+ * Forward declaration of frontend-specific channel and ring_buffer.
+ */
+struct channel;
+struct lib_ring_buffer;
+
+struct lib_ring_buffer_backend {
+ /* Array of ring_buffer_backend_subbuffer for writer */
+ struct lib_ring_buffer_backend_subbuffer *buf_wsb;
+ /* ring_buffer_backend_subbuffer for reader */
+ struct lib_ring_buffer_backend_subbuffer buf_rsb;
+ /*
+ * Pointer array of backend pages, for whole buffer.
+ * Indexed by ring_buffer_backend_subbuffer identifier (id) index.
+ */
+ struct lib_ring_buffer_backend_pages **array;
+ unsigned int num_pages_per_subbuf;
+
+ struct channel *chan; /* Associated channel */
+ int cpu; /* This buffer's cpu. -1 if global. */
+ union v_atomic records_read; /* Number of records read */
+ unsigned int allocated:1; /* Bool: is buffer allocated ? */
+};
+
+struct channel_backend {
+ unsigned long buf_size; /* Size of the buffer */
+ unsigned long subbuf_size; /* Sub-buffer size */
+ unsigned int subbuf_size_order; /* Order of sub-buffer size */
+ unsigned int num_subbuf_order; /*
+ * Order of number of sub-buffers/buffer
+ * for writer.
+ */
+ unsigned int buf_size_order; /* Order of buffer size */
+ int extra_reader_sb:1; /* Bool: has extra reader subbuffer */
+ struct lib_ring_buffer *buf; /* Channel per-cpu buffers */
+
+ unsigned long num_subbuf; /* Number of sub-buffers for writer */
+ u64 start_tsc; /* Channel creation TSC value */
+ void *priv; /* Client-specific information */
+ struct notifier_block cpu_hp_notifier; /* CPU hotplug notifier */
+ const struct lib_ring_buffer_config *config; /* Ring buffer configuration */
+ cpumask_var_t cpumask; /* Allocated per-cpu buffers cpumask */
+ char name[NAME_MAX]; /* Channel name */
+};
+
+#endif /* _LINUX_RING_BUFFER_BACKEND_TYPES_H */
diff --git a/drivers/staging/lttng/lib/ringbuffer/config.h b/drivers/staging/lttng/lib/ringbuffer/config.h
new file mode 100644
index 0000000..fd73d55
--- /dev/null
+++ b/drivers/staging/lttng/lib/ringbuffer/config.h
@@ -0,0 +1,298 @@
+#ifndef _LINUX_RING_BUFFER_CONFIG_H
+#define _LINUX_RING_BUFFER_CONFIG_H
+
+/*
+ * linux/ringbuffer/config.h
+ *
+ * Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Ring buffer configuration header. Note: after declaring the standard inline
+ * functions, clients should also include linux/ringbuffer/api.h.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/types.h>
+#include <linux/percpu.h>
+#include "../align.h"
+
+struct lib_ring_buffer;
+struct channel;
+struct lib_ring_buffer_config;
+struct lib_ring_buffer_ctx;
+
+/*
+ * Ring buffer client callbacks. Only used by slow path, never on fast path.
+ * For the fast path, record_header_size(), ring_buffer_clock_read() should be
+ * provided as inline functions too. These may simply return 0 if not used by
+ * the client.
+ */
+struct lib_ring_buffer_client_cb {
+ /* Mandatory callbacks */
+
+ /* A static inline version is also required for fast path */
+ u64 (*ring_buffer_clock_read) (struct channel *chan);
+ size_t (*record_header_size) (const struct lib_ring_buffer_config *config,
+ struct channel *chan, size_t offset,
+ size_t *pre_header_padding,
+ struct lib_ring_buffer_ctx *ctx);
+
+ /* Slow path only, at subbuffer switch */
+ size_t (*subbuffer_header_size) (void);
+ void (*buffer_begin) (struct lib_ring_buffer *buf, u64 tsc,
+ unsigned int subbuf_idx);
+ void (*buffer_end) (struct lib_ring_buffer *buf, u64 tsc,
+ unsigned int subbuf_idx, unsigned long data_size);
+
+ /* Optional callbacks (can be set to NULL) */
+
+ /* Called at buffer creation/finalize */
+ int (*buffer_create) (struct lib_ring_buffer *buf, void *priv,
+ int cpu, const char *name);
+ /*
+ * Clients should guarantee that no new reader handle can be opened
+ * after finalize.
+ */
+ void (*buffer_finalize) (struct lib_ring_buffer *buf, void *priv, int cpu);
+
+ /*
+ * Extract header length, payload length and timestamp from event
+ * record. Used by buffer iterators. Timestamp is only used by channel
+ * iterator.
+ */
+ void (*record_get) (const struct lib_ring_buffer_config *config,
+ struct channel *chan, struct lib_ring_buffer *buf,
+ size_t offset, size_t *header_len,
+ size_t *payload_len, u64 *timestamp);
+};
+
+/*
+ * Ring buffer instance configuration.
+ *
+ * Declare as "static const" within the client object to ensure the inline fast
+ * paths can be optimized.
+ *
+ * alloc/sync pairs:
+ *
+ * RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_PER_CPU :
+ * Per-cpu buffers with per-cpu synchronization. Tracing must be performed
+ * with preemption disabled (lib_ring_buffer_get_cpu() and
+ * lib_ring_buffer_put_cpu()).
+ *
+ * RING_BUFFER_ALLOC_PER_CPU and RING_BUFFER_SYNC_GLOBAL :
+ * Per-cpu buffer with global synchronization. Tracing can be performed with
+ * preemption enabled, statistically stays on the local buffers.
+ *
+ * RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_PER_CPU :
+ * Should only be used for buffers belonging to a single thread or protected
+ * by mutual exclusion by the client. Note that periodical sub-buffer switch
+ * should be disabled in this kind of configuration.
+ *
+ * RING_BUFFER_ALLOC_GLOBAL and RING_BUFFER_SYNC_GLOBAL :
+ * Global shared buffer with global synchronization.
+ *
+ * wakeup:
+ *
+ * RING_BUFFER_WAKEUP_BY_TIMER uses per-cpu deferrable timers to poll the
+ * buffers and wake up readers if data is ready. Mainly useful for tracers which
+ * don't want to call into the wakeup code on the tracing path. Use in
+ * combination with "read_timer_interval" channel_create() argument.
+ *
+ * RING_BUFFER_WAKEUP_BY_WRITER directly wakes up readers when a subbuffer is
+ * ready to read. Lower latencies before the reader is woken up. Mainly suitable
+ * for drivers.
+ *
+ * RING_BUFFER_WAKEUP_NONE does not perform any wakeup whatsoever. The client
+ * has the responsibility to perform wakeups.
+ */
+struct lib_ring_buffer_config {
+ enum {
+ RING_BUFFER_ALLOC_PER_CPU,
+ RING_BUFFER_ALLOC_GLOBAL,
+ } alloc;
+ enum {
+ RING_BUFFER_SYNC_PER_CPU, /* Wait-free */
+ RING_BUFFER_SYNC_GLOBAL, /* Lock-free */
+ } sync;
+ enum {
+ RING_BUFFER_OVERWRITE, /* Overwrite when buffer full */
+ RING_BUFFER_DISCARD, /* Discard when buffer full */
+ } mode;
+ enum {
+ RING_BUFFER_SPLICE,
+ RING_BUFFER_MMAP,
+ RING_BUFFER_READ, /* TODO */
+ RING_BUFFER_ITERATOR,
+ RING_BUFFER_NONE,
+ } output;
+ enum {
+ RING_BUFFER_PAGE,
+ RING_BUFFER_VMAP, /* TODO */
+ RING_BUFFER_STATIC, /* TODO */
+ } backend;
+ enum {
+ RING_BUFFER_NO_OOPS_CONSISTENCY,
+ RING_BUFFER_OOPS_CONSISTENCY,
+ } oops;
+ enum {
+ RING_BUFFER_IPI_BARRIER,
+ RING_BUFFER_NO_IPI_BARRIER,
+ } ipi;
+ enum {
+ RING_BUFFER_WAKEUP_BY_TIMER, /* wake up performed by timer */
+ RING_BUFFER_WAKEUP_BY_WRITER, /*
+ * writer wakes up reader,
+ * not lock-free
+ * (takes spinlock).
+ */
+ } wakeup;
+ /*
+ * tsc_bits: timestamp bits saved at each record.
+ * 0 and 64 disable the timestamp compression scheme.
+ */
+ unsigned int tsc_bits;
+ struct lib_ring_buffer_client_cb cb;
+};
+
+/*
+ * ring buffer context
+ *
+ * Context passed to lib_ring_buffer_reserve(), lib_ring_buffer_commit(),
+ * lib_ring_buffer_try_discard_reserve(), lib_ring_buffer_align_ctx() and
+ * lib_ring_buffer_write().
+ */
+struct lib_ring_buffer_ctx {
+ /* input received by lib_ring_buffer_reserve(), saved here. */
+ struct channel *chan; /* channel */
+ void *priv; /* client private data */
+ size_t data_size; /* size of payload */
+ int largest_align; /*
+ * alignment of the largest element
+ * in the payload
+ */
+ int cpu; /* processor id */
+
+ /* output from lib_ring_buffer_reserve() */
+ struct lib_ring_buffer *buf; /*
+ * buffer corresponding to processor id
+ * for this channel
+ */
+ size_t slot_size; /* size of the reserved slot */
+ unsigned long buf_offset; /* offset following the record header */
+ unsigned long pre_offset; /*
+ * Initial offset position _before_
+ * the record is written. Positioned
+ * prior to record header alignment
+ * padding.
+ */
+ u64 tsc; /* time-stamp counter value */
+ unsigned int rflags; /* reservation flags */
+};
+
+/**
+ * lib_ring_buffer_ctx_init - initialize ring buffer context
+ * @ctx: ring buffer context to initialize
+ * @chan: channel
+ * @priv: client private data
+ * @data_size: size of record data payload
+ * @largest_align: largest alignment within data payload types
+ * @cpu: processor id
+ */
+static inline
+void lib_ring_buffer_ctx_init(struct lib_ring_buffer_ctx *ctx,
+ struct channel *chan, void *priv,
+ size_t data_size, int largest_align,
+ int cpu)
+{
+ ctx->chan = chan;
+ ctx->priv = priv;
+ ctx->data_size = data_size;
+ ctx->largest_align = largest_align;
+ ctx->cpu = cpu;
+ ctx->rflags = 0;
+}
+
+/*
+ * Reservation flags.
+ *
+ * RING_BUFFER_RFLAG_FULL_TSC
+ *
+ * This flag is passed to record_header_size() and to the primitive used to
+ * write the record header. It indicates that the full 64-bit time value is
+ * needed in the record header. If this flag is not set, the record header needs
+ * only to contain "tsc_bits" bit of time value.
+ *
+ * Reservation flags can be added by the client, starting from
+ * "(RING_BUFFER_FLAGS_END << 0)". It can be used to pass information from
+ * record_header_size() to lib_ring_buffer_write_record_header().
+ */
+#define RING_BUFFER_RFLAG_FULL_TSC (1U << 0)
+#define RING_BUFFER_RFLAG_END (1U << 1)
+
+/*
+ * We need to define RING_BUFFER_ALIGN_ATTR so it is known early at
+ * compile-time. We have to duplicate the "config->align" information and the
+ * definition here because config->align is used both in the slow and fast
+ * paths, but RING_BUFFER_ALIGN_ATTR is only available for the client code.
+ */
+#ifdef RING_BUFFER_ALIGN
+
+# define RING_BUFFER_ALIGN_ATTR /* Default arch alignment */
+
+/*
+ * Calculate the offset needed to align the type.
+ * size_of_type must be non-zero.
+ */
+static inline
+unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type)
+{
+ return offset_align(align_drift, size_of_type);
+}
+
+#else
+
+# define RING_BUFFER_ALIGN_ATTR __attribute__((packed))
+
+/*
+ * Calculate the offset needed to align the type.
+ * size_of_type must be non-zero.
+ */
+static inline
+unsigned int lib_ring_buffer_align(size_t align_drift, size_t size_of_type)
+{
+ return 0;
+}
+
+#endif
+
+/**
+ * lib_ring_buffer_align_ctx - Align context offset on "alignment"
+ * @ctx: ring buffer context.
+ */
+static inline
+void lib_ring_buffer_align_ctx(struct lib_ring_buffer_ctx *ctx,
+ size_t alignment)
+{
+ ctx->buf_offset += lib_ring_buffer_align(ctx->buf_offset,
+ alignment);
+}
+
+/*
+ * lib_ring_buffer_check_config() returns 0 on success.
+ * Used internally to check for valid configurations at channel creation.
+ */
+static inline
+int lib_ring_buffer_check_config(const struct lib_ring_buffer_config *config,
+ unsigned int switch_timer_interval,
+ unsigned int read_timer_interval)
+{
+ if (config->alloc == RING_BUFFER_ALLOC_GLOBAL
+ && config->sync == RING_BUFFER_SYNC_PER_CPU
+ && switch_timer_interval)
+ return -EINVAL;
+ return 0;
+}
+
+#include "../../wrapper/ringbuffer/vatomic.h"
+
+#endif /* _LINUX_RING_BUFFER_CONFIG_H */
diff --git a/drivers/staging/lttng/lib/ringbuffer/frontend.h b/drivers/staging/lttng/lib/ringbuffer/frontend.h
new file mode 100644
index 0000000..01af77a
--- /dev/null
+++ b/drivers/staging/lttng/lib/ringbuffer/frontend.h
@@ -0,0 +1,228 @@
+#ifndef _LINUX_RING_BUFFER_FRONTEND_H
+#define _LINUX_RING_BUFFER_FRONTEND_H
+
+/*
+ * linux/ringbuffer/frontend.h
+ *
+ * (C) Copyright 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Ring Buffer Library Synchronization Header (API).
+ *
+ * Author:
+ * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * See ring_buffer_frontend.c for more information on wait-free algorithms.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/pipe_fs_i.h>
+#include <linux/rcupdate.h>
+#include <linux/cpumask.h>
+#include <linux/module.h>
+#include <linux/bitops.h>
+#include <linux/splice.h>
+#include <linux/string.h>
+#include <linux/timer.h>
+#include <linux/sched.h>
+#include <linux/cache.h>
+#include <linux/time.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/stat.h>
+#include <linux/cpu.h>
+#include <linux/fs.h>
+
+#include <asm/atomic.h>
+#include <asm/local.h>
+
+/* Internal helpers */
+#include "../../wrapper/ringbuffer/frontend_internal.h"
+
+/* Buffer creation/removal and setup operations */
+
+/*
+ * switch_timer_interval is the time interval (in us) to fill sub-buffers with
+ * padding to let readers get those sub-buffers. Used for live streaming.
+ *
+ * read_timer_interval is the time interval (in us) to wake up pending readers.
+ *
+ * buf_addr is a pointer the the beginning of the preallocated buffer contiguous
+ * address mapping. It is used only by RING_BUFFER_STATIC configuration. It can
+ * be set to NULL for other backends.
+ */
+
+extern
+struct channel *channel_create(const struct lib_ring_buffer_config *config,
+ const char *name, void *priv,
+ void *buf_addr,
+ size_t subbuf_size, size_t num_subbuf,
+ unsigned int switch_timer_interval,
+ unsigned int read_timer_interval);
+
+/*
+ * channel_destroy returns the private data pointer. It finalizes all channel's
+ * buffers, waits for readers to release all references, and destroys the
+ * channel.
+ */
+extern
+void *channel_destroy(struct channel *chan);
+
+
+/* Buffer read operations */
+
+/*
+ * Iteration on channel cpumask needs to issue a read barrier to match the write
+ * barrier in cpu hotplug. It orders the cpumask read before read of per-cpu
+ * buffer data. The per-cpu buffer is never removed by cpu hotplug; teardown is
+ * only performed at channel destruction.
+ */
+#define for_each_channel_cpu(cpu, chan) \
+ for ((cpu) = -1; \
+ ({ (cpu) = cpumask_next(cpu, (chan)->backend.cpumask); \
+ smp_read_barrier_depends(); (cpu) < nr_cpu_ids; });)
+
+extern struct lib_ring_buffer *channel_get_ring_buffer(
+ const struct lib_ring_buffer_config *config,
+ struct channel *chan, int cpu);
+extern int lib_ring_buffer_open_read(struct lib_ring_buffer *buf);
+extern void lib_ring_buffer_release_read(struct lib_ring_buffer *buf);
+
+/*
+ * Read sequence: snapshot, many get_subbuf/put_subbuf, move_consumer.
+ */
+extern int lib_ring_buffer_snapshot(struct lib_ring_buffer *buf,
+ unsigned long *consumed,
+ unsigned long *produced);
+extern void lib_ring_buffer_move_consumer(struct lib_ring_buffer *buf,
+ unsigned long consumed_new);
+
+extern int lib_ring_buffer_get_subbuf(struct lib_ring_buffer *buf,
+ unsigned long consumed);
+extern void lib_ring_buffer_put_subbuf(struct lib_ring_buffer *buf);
+
+/*
+ * lib_ring_buffer_get_next_subbuf/lib_ring_buffer_put_next_subbuf are helpers
+ * to read sub-buffers sequentially.
+ */
+static inline int lib_ring_buffer_get_next_subbuf(struct lib_ring_buffer *buf)
+{
+ int ret;
+
+ ret = lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
+ &buf->prod_snapshot);
+ if (ret)
+ return ret;
+ ret = lib_ring_buffer_get_subbuf(buf, buf->cons_snapshot);
+ return ret;
+}
+
+static inline void lib_ring_buffer_put_next_subbuf(struct lib_ring_buffer *buf)
+{
+ lib_ring_buffer_put_subbuf(buf);
+ lib_ring_buffer_move_consumer(buf, subbuf_align(buf->cons_snapshot,
+ buf->backend.chan));
+}
+
+extern void channel_reset(struct channel *chan);
+extern void lib_ring_buffer_reset(struct lib_ring_buffer *buf);
+
+static inline
+unsigned long lib_ring_buffer_get_offset(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->offset);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_consumed(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ return atomic_long_read(&buf->consumed);
+}
+
+/*
+ * Must call lib_ring_buffer_is_finalized before reading counters (memory
+ * ordering enforced with respect to trace teardown).
+ */
+static inline
+int lib_ring_buffer_is_finalized(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ int finalized = ACCESS_ONCE(buf->finalized);
+ /*
+ * Read finalized before counters.
+ */
+ smp_rmb();
+ return finalized;
+}
+
+static inline
+int lib_ring_buffer_channel_is_finalized(const struct channel *chan)
+{
+ return chan->finalized;
+}
+
+static inline
+int lib_ring_buffer_channel_is_disabled(const struct channel *chan)
+{
+ return atomic_read(&chan->record_disabled);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_read_data_size(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ return subbuffer_get_read_data_size(config, &buf->backend);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_records_count(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->records_count);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_records_overrun(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->records_overrun);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_records_lost_full(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->records_lost_full);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_records_lost_wrap(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->records_lost_wrap);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_records_lost_big(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->records_lost_big);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_records_read(
+ const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ return v_read(config, &buf->backend.records_read);
+}
+
+#endif /* _LINUX_RING_BUFFER_FRONTEND_H */
diff --git a/drivers/staging/lttng/lib/ringbuffer/frontend_api.h b/drivers/staging/lttng/lib/ringbuffer/frontend_api.h
new file mode 100644
index 0000000..391e593
--- /dev/null
+++ b/drivers/staging/lttng/lib/ringbuffer/frontend_api.h
@@ -0,0 +1,358 @@
+#ifndef _LINUX_RING_BUFFER_FRONTEND_API_H
+#define _LINUX_RING_BUFFER_FRONTEND_API_H
+
+/*
+ * linux/ringbuffer/frontend_api.h
+ *
+ * (C) Copyright 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Ring Buffer Library Synchronization Header (buffer write API).
+ *
+ * Author:
+ * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * See ring_buffer_frontend.c for more information on wait-free algorithms.
+ * See linux/ringbuffer/frontend.h for channel allocation and read-side API.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include "../../wrapper/ringbuffer/frontend.h"
+#include <linux/errno.h>
+
+/**
+ * lib_ring_buffer_get_cpu - Precedes ring buffer reserve/commit.
+ *
+ * Disables preemption (acts as a RCU read-side critical section) and keeps a
+ * ring buffer nesting count as supplementary safety net to ensure tracer client
+ * code will never trigger an endless recursion. Returns the processor ID on
+ * success, -EPERM on failure (nesting count too high).
+ *
+ * asm volatile and "memory" clobber prevent the compiler from moving
+ * instructions out of the ring buffer nesting count. This is required to ensure
+ * that probe side-effects which can cause recursion (e.g. unforeseen traps,
+ * divisions by 0, ...) are triggered within the incremented nesting count
+ * section.
+ */
+static inline
+int lib_ring_buffer_get_cpu(const struct lib_ring_buffer_config *config)
+{
+ int cpu, nesting;
+
+ rcu_read_lock_sched_notrace();
+ cpu = smp_processor_id();
+ nesting = ++per_cpu(lib_ring_buffer_nesting, cpu);
+ barrier();
+
+ if (unlikely(nesting > 4)) {
+ WARN_ON_ONCE(1);
+ per_cpu(lib_ring_buffer_nesting, cpu)--;
+ rcu_read_unlock_sched_notrace();
+ return -EPERM;
+ } else
+ return cpu;
+}
+
+/**
+ * lib_ring_buffer_put_cpu - Follows ring buffer reserve/commit.
+ */
+static inline
+void lib_ring_buffer_put_cpu(const struct lib_ring_buffer_config *config)
+{
+ barrier();
+ __get_cpu_var(lib_ring_buffer_nesting)--;
+ rcu_read_unlock_sched_notrace();
+}
+
+/*
+ * lib_ring_buffer_try_reserve is called by lib_ring_buffer_reserve(). It is not
+ * part of the API per se.
+ *
+ * returns 0 if reserve ok, or 1 if the slow path must be taken.
+ */
+static inline
+int lib_ring_buffer_try_reserve(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_ctx *ctx,
+ unsigned long *o_begin, unsigned long *o_end,
+ unsigned long *o_old, size_t *before_hdr_pad)
+{
+ struct channel *chan = ctx->chan;
+ struct lib_ring_buffer *buf = ctx->buf;
+ *o_begin = v_read(config, &buf->offset);
+ *o_old = *o_begin;
+
+ ctx->tsc = lib_ring_buffer_clock_read(chan);
+ if ((int64_t) ctx->tsc == -EIO)
+ return 1;
+
+ /*
+ * Prefetch cacheline for read because we have to read the previous
+ * commit counter to increment it and commit seq value to compare it to
+ * the commit counter.
+ */
+ prefetch(&buf->commit_hot[subbuf_index(*o_begin, chan)]);
+
+ if (last_tsc_overflow(config, buf, ctx->tsc))
+ ctx->rflags |= RING_BUFFER_RFLAG_FULL_TSC;
+
+ if (unlikely(subbuf_offset(*o_begin, chan) == 0))
+ return 1;
+
+ ctx->slot_size = record_header_size(config, chan, *o_begin,
+ before_hdr_pad, ctx);
+ ctx->slot_size +=
+ lib_ring_buffer_align(*o_begin + ctx->slot_size,
+ ctx->largest_align) + ctx->data_size;
+ if (unlikely((subbuf_offset(*o_begin, chan) + ctx->slot_size)
+ > chan->backend.subbuf_size))
+ return 1;
+
+ /*
+ * Record fits in the current buffer and we are not on a switch
+ * boundary. It's safe to write.
+ */
+ *o_end = *o_begin + ctx->slot_size;
+
+ if (unlikely((subbuf_offset(*o_end, chan)) == 0))
+ /*
+ * The offset_end will fall at the very beginning of the next
+ * subbuffer.
+ */
+ return 1;
+
+ return 0;
+}
+
+/**
+ * lib_ring_buffer_reserve - Reserve space in a ring buffer.
+ * @config: ring buffer instance configuration.
+ * @ctx: ring buffer context. (input and output) Must be already initialized.
+ *
+ * Atomic wait-free slot reservation. The reserved space starts at the context
+ * "pre_offset". Its length is "slot_size". The associated time-stamp is "tsc".
+ *
+ * Return :
+ * 0 on success.
+ * -EAGAIN if channel is disabled.
+ * -ENOSPC if event size is too large for packet.
+ * -ENOBUFS if there is currently not enough space in buffer for the event.
+ * -EIO if data cannot be written into the buffer for any other reason.
+ */
+
+static inline
+int lib_ring_buffer_reserve(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_ctx *ctx)
+{
+ struct channel *chan = ctx->chan;
+ struct lib_ring_buffer *buf;
+ unsigned long o_begin, o_end, o_old;
+ size_t before_hdr_pad = 0;
+
+ if (atomic_read(&chan->record_disabled))
+ return -EAGAIN;
+
+ if (config->alloc == RING_BUFFER_ALLOC_PER_CPU)
+ buf = per_cpu_ptr(chan->backend.buf, ctx->cpu);
+ else
+ buf = chan->backend.buf;
+ if (atomic_read(&buf->record_disabled))
+ return -EAGAIN;
+ ctx->buf = buf;
+
+ /*
+ * Perform retryable operations.
+ */
+ if (unlikely(lib_ring_buffer_try_reserve(config, ctx, &o_begin,
+ &o_end, &o_old, &before_hdr_pad)))
+ goto slow_path;
+
+ if (unlikely(v_cmpxchg(config, &ctx->buf->offset, o_old, o_end)
+ != o_old))
+ goto slow_path;
+
+ /*
+ * Atomically update last_tsc. This update races against concurrent
+ * atomic updates, but the race will always cause supplementary full TSC
+ * record headers, never the opposite (missing a full TSC record header
+ * when it would be needed).
+ */
+ save_last_tsc(config, ctx->buf, ctx->tsc);
+
+ /*
+ * Push the reader if necessary
+ */
+ lib_ring_buffer_reserve_push_reader(ctx->buf, chan, o_end - 1);
+
+ /*
+ * Clear noref flag for this subbuffer.
+ */
+ lib_ring_buffer_clear_noref(config, &ctx->buf->backend,
+ subbuf_index(o_end - 1, chan));
+
+ ctx->pre_offset = o_begin;
+ ctx->buf_offset = o_begin + before_hdr_pad;
+ return 0;
+slow_path:
+ return lib_ring_buffer_reserve_slow(ctx);
+}
+
+/**
+ * lib_ring_buffer_switch - Perform a sub-buffer switch for a per-cpu buffer.
+ * @config: ring buffer instance configuration.
+ * @buf: buffer
+ * @mode: buffer switch mode (SWITCH_ACTIVE or SWITCH_FLUSH)
+ *
+ * This operation is completely reentrant : can be called while tracing is
+ * active with absolutely no lock held.
+ *
+ * Note, however, that as a v_cmpxchg is used for some atomic operations and
+ * requires to be executed locally for per-CPU buffers, this function must be
+ * called from the CPU which owns the buffer for a ACTIVE flush, with preemption
+ * disabled, for RING_BUFFER_SYNC_PER_CPU configuration.
+ */
+static inline
+void lib_ring_buffer_switch(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf, enum switch_mode mode)
+{
+ lib_ring_buffer_switch_slow(buf, mode);
+}
+
+/* See ring_buffer_frontend_api.h for lib_ring_buffer_reserve(). */
+
+/**
+ * lib_ring_buffer_commit - Commit an record.
+ * @config: ring buffer instance configuration.
+ * @ctx: ring buffer context. (input arguments only)
+ *
+ * Atomic unordered slot commit. Increments the commit count in the
+ * specified sub-buffer, and delivers it if necessary.
+ */
+static inline
+void lib_ring_buffer_commit(const struct lib_ring_buffer_config *config,
+ const struct lib_ring_buffer_ctx *ctx)
+{
+ struct channel *chan = ctx->chan;
+ struct lib_ring_buffer *buf = ctx->buf;
+ unsigned long offset_end = ctx->buf_offset;
+ unsigned long endidx = subbuf_index(offset_end - 1, chan);
+ unsigned long commit_count;
+
+ /*
+ * Must count record before incrementing the commit count.
+ */
+ subbuffer_count_record(config, &buf->backend, endidx);
+
+ /*
+ * Order all writes to buffer before the commit count update that will
+ * determine that the subbuffer is full.
+ */
+ if (config->ipi == RING_BUFFER_IPI_BARRIER) {
+ /*
+ * Must write slot data before incrementing commit count. This
+ * compiler barrier is upgraded into a smp_mb() by the IPI sent
+ * by get_subbuf().
+ */
+ barrier();
+ } else
+ smp_wmb();
+
+ v_add(config, ctx->slot_size, &buf->commit_hot[endidx].cc);
+
+ /*
+ * commit count read can race with concurrent OOO commit count updates.
+ * This is only needed for lib_ring_buffer_check_deliver (for
+ * non-polling delivery only) and for
+ * lib_ring_buffer_write_commit_counter. The race can only cause the
+ * counter to be read with the same value more than once, which could
+ * cause :
+ * - Multiple delivery for the same sub-buffer (which is handled
+ * gracefully by the reader code) if the value is for a full
+ * sub-buffer. It's important that we can never miss a sub-buffer
+ * delivery. Re-reading the value after the v_add ensures this.
+ * - Reading a commit_count with a higher value that what was actually
+ * added to it for the lib_ring_buffer_write_commit_counter call
+ * (again caused by a concurrent committer). It does not matter,
+ * because this function is interested in the fact that the commit
+ * count reaches back the reserve offset for a specific sub-buffer,
+ * which is completely independent of the order.
+ */
+ commit_count = v_read(config, &buf->commit_hot[endidx].cc);
+
+ lib_ring_buffer_check_deliver(config, buf, chan, offset_end - 1,
+ commit_count, endidx);
+ /*
+ * Update used size at each commit. It's needed only for extracting
+ * ring_buffer buffers from vmcore, after crash.
+ */
+ lib_ring_buffer_write_commit_counter(config, buf, chan, endidx,
+ ctx->buf_offset, commit_count,
+ ctx->slot_size);
+}
+
+/**
+ * lib_ring_buffer_try_discard_reserve - Try discarding a record.
+ * @config: ring buffer instance configuration.
+ * @ctx: ring buffer context. (input arguments only)
+ *
+ * Only succeeds if no other record has been written after the record to
+ * discard. If discard fails, the record must be committed to the buffer.
+ *
+ * Returns 0 upon success, -EPERM if the record cannot be discarded.
+ */
+static inline
+int lib_ring_buffer_try_discard_reserve(const struct lib_ring_buffer_config *config,
+ const struct lib_ring_buffer_ctx *ctx)
+{
+ struct lib_ring_buffer *buf = ctx->buf;
+ unsigned long end_offset = ctx->pre_offset + ctx->slot_size;
+
+ /*
+ * We need to ensure that if the cmpxchg succeeds and discards the
+ * record, the next record will record a full TSC, because it cannot
+ * rely on the last_tsc associated with the discarded record to detect
+ * overflows. The only way to ensure this is to set the last_tsc to 0
+ * (assuming no 64-bit TSC overflow), which forces to write a 64-bit
+ * timestamp in the next record.
+ *
+ * Note: if discard fails, we must leave the TSC in the record header.
+ * It is needed to keep track of TSC overflows for the following
+ * records.
+ */
+ save_last_tsc(config, buf, 0ULL);
+
+ if (likely(v_cmpxchg(config, &buf->offset, end_offset, ctx->pre_offset)
+ != end_offset))
+ return -EPERM;
+ else
+ return 0;
+}
+
+static inline
+void channel_record_disable(const struct lib_ring_buffer_config *config,
+ struct channel *chan)
+{
+ atomic_inc(&chan->record_disabled);
+}
+
+static inline
+void channel_record_enable(const struct lib_ring_buffer_config *config,
+ struct channel *chan)
+{
+ atomic_dec(&chan->record_disabled);
+}
+
+static inline
+void lib_ring_buffer_record_disable(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ atomic_inc(&buf->record_disabled);
+}
+
+static inline
+void lib_ring_buffer_record_enable(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf)
+{
+ atomic_dec(&buf->record_disabled);
+}
+
+#endif /* _LINUX_RING_BUFFER_FRONTEND_API_H */
diff --git a/drivers/staging/lttng/lib/ringbuffer/frontend_internal.h b/drivers/staging/lttng/lib/ringbuffer/frontend_internal.h
new file mode 100644
index 0000000..3bd5721
--- /dev/null
+++ b/drivers/staging/lttng/lib/ringbuffer/frontend_internal.h
@@ -0,0 +1,424 @@
+#ifndef _LINUX_RING_BUFFER_FRONTEND_INTERNAL_H
+#define _LINUX_RING_BUFFER_FRONTEND_INTERNAL_H
+
+/*
+ * linux/ringbuffer/frontend_internal.h
+ *
+ * (C) Copyright 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Ring Buffer Library Synchronization Header (internal helpers).
+ *
+ * Author:
+ * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * See ring_buffer_frontend.c for more information on wait-free algorithms.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include "../../wrapper/ringbuffer/config.h"
+#include "../../wrapper/ringbuffer/backend_types.h"
+#include "../../wrapper/ringbuffer/frontend_types.h"
+#include "../../lib/prio_heap/lttng_prio_heap.h" /* For per-CPU read-side iterator */
+
+/* Buffer offset macros */
+
+/* buf_trunc mask selects only the buffer number. */
+static inline
+unsigned long buf_trunc(unsigned long offset, struct channel *chan)
+{
+ return offset & ~(chan->backend.buf_size - 1);
+
+}
+
+/* Select the buffer number value (counter). */
+static inline
+unsigned long buf_trunc_val(unsigned long offset, struct channel *chan)
+{
+ return buf_trunc(offset, chan) >> chan->backend.buf_size_order;
+}
+
+/* buf_offset mask selects only the offset within the current buffer. */
+static inline
+unsigned long buf_offset(unsigned long offset, struct channel *chan)
+{
+ return offset & (chan->backend.buf_size - 1);
+}
+
+/* subbuf_offset mask selects the offset within the current subbuffer. */
+static inline
+unsigned long subbuf_offset(unsigned long offset, struct channel *chan)
+{
+ return offset & (chan->backend.subbuf_size - 1);
+}
+
+/* subbuf_trunc mask selects the subbuffer number. */
+static inline
+unsigned long subbuf_trunc(unsigned long offset, struct channel *chan)
+{
+ return offset & ~(chan->backend.subbuf_size - 1);
+}
+
+/* subbuf_align aligns the offset to the next subbuffer. */
+static inline
+unsigned long subbuf_align(unsigned long offset, struct channel *chan)
+{
+ return (offset + chan->backend.subbuf_size)
+ & ~(chan->backend.subbuf_size - 1);
+}
+
+/* subbuf_index returns the index of the current subbuffer within the buffer. */
+static inline
+unsigned long subbuf_index(unsigned long offset, struct channel *chan)
+{
+ return buf_offset(offset, chan) >> chan->backend.subbuf_size_order;
+}
+
+/*
+ * Last TSC comparison functions. Check if the current TSC overflows tsc_bits
+ * bits from the last TSC read. When overflows are detected, the full 64-bit
+ * timestamp counter should be written in the record header. Reads and writes
+ * last_tsc atomically.
+ */
+
+#if (BITS_PER_LONG == 32)
+static inline
+void save_last_tsc(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf, u64 tsc)
+{
+ if (config->tsc_bits == 0 || config->tsc_bits == 64)
+ return;
+
+ /*
+ * Ensure the compiler performs this update in a single instruction.
+ */
+ v_set(config, &buf->last_tsc, (unsigned long)(tsc >> config->tsc_bits));
+}
+
+static inline
+int last_tsc_overflow(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf, u64 tsc)
+{
+ unsigned long tsc_shifted;
+
+ if (config->tsc_bits == 0 || config->tsc_bits == 64)
+ return 0;
+
+ tsc_shifted = (unsigned long)(tsc >> config->tsc_bits);
+ if (unlikely(tsc_shifted
+ - (unsigned long)v_read(config, &buf->last_tsc)))
+ return 1;
+ else
+ return 0;
+}
+#else
+static inline
+void save_last_tsc(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf, u64 tsc)
+{
+ if (config->tsc_bits == 0 || config->tsc_bits == 64)
+ return;
+
+ v_set(config, &buf->last_tsc, (unsigned long)tsc);
+}
+
+static inline
+int last_tsc_overflow(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf, u64 tsc)
+{
+ if (config->tsc_bits == 0 || config->tsc_bits == 64)
+ return 0;
+
+ if (unlikely((tsc - v_read(config, &buf->last_tsc))
+ >> config->tsc_bits))
+ return 1;
+ else
+ return 0;
+}
+#endif
+
+extern
+int lib_ring_buffer_reserve_slow(struct lib_ring_buffer_ctx *ctx);
+
+extern
+void lib_ring_buffer_switch_slow(struct lib_ring_buffer *buf,
+ enum switch_mode mode);
+
+/* Buffer write helpers */
+
+static inline
+void lib_ring_buffer_reserve_push_reader(struct lib_ring_buffer *buf,
+ struct channel *chan,
+ unsigned long offset)
+{
+ unsigned long consumed_old, consumed_new;
+
+ do {
+ consumed_old = atomic_long_read(&buf->consumed);
+ /*
+ * If buffer is in overwrite mode, push the reader consumed
+ * count if the write position has reached it and we are not
+ * at the first iteration (don't push the reader farther than
+ * the writer). This operation can be done concurrently by many
+ * writers in the same buffer, the writer being at the farthest
+ * write position sub-buffer index in the buffer being the one
+ * which will win this loop.
+ */
+ if (unlikely(subbuf_trunc(offset, chan)
+ - subbuf_trunc(consumed_old, chan)
+ >= chan->backend.buf_size))
+ consumed_new = subbuf_align(consumed_old, chan);
+ else
+ return;
+ } while (unlikely(atomic_long_cmpxchg(&buf->consumed, consumed_old,
+ consumed_new) != consumed_old));
+}
+
+static inline
+void lib_ring_buffer_vmcore_check_deliver(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf,
+ unsigned long commit_count,
+ unsigned long idx)
+{
+ if (config->oops == RING_BUFFER_OOPS_CONSISTENCY)
+ v_set(config, &buf->commit_hot[idx].seq, commit_count);
+}
+
+static inline
+int lib_ring_buffer_poll_deliver(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf,
+ struct channel *chan)
+{
+ unsigned long consumed_old, consumed_idx, commit_count, write_offset;
+
+ consumed_old = atomic_long_read(&buf->consumed);
+ consumed_idx = subbuf_index(consumed_old, chan);
+ commit_count = v_read(config, &buf->commit_cold[consumed_idx].cc_sb);
+ /*
+ * No memory barrier here, since we are only interested
+ * in a statistically correct polling result. The next poll will
+ * get the data is we are racing. The mb() that ensures correct
+ * memory order is in get_subbuf.
+ */
+ write_offset = v_read(config, &buf->offset);
+
+ /*
+ * Check that the subbuffer we are trying to consume has been
+ * already fully committed.
+ */
+
+ if (((commit_count - chan->backend.subbuf_size)
+ & chan->commit_count_mask)
+ - (buf_trunc(consumed_old, chan)
+ >> chan->backend.num_subbuf_order)
+ != 0)
+ return 0;
+
+ /*
+ * Check that we are not about to read the same subbuffer in
+ * which the writer head is.
+ */
+ if (subbuf_trunc(write_offset, chan) - subbuf_trunc(consumed_old, chan)
+ == 0)
+ return 0;
+
+ return 1;
+
+}
+
+static inline
+int lib_ring_buffer_pending_data(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf,
+ struct channel *chan)
+{
+ return !!subbuf_offset(v_read(config, &buf->offset), chan);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_data_size(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf,
+ unsigned long idx)
+{
+ return subbuffer_get_data_size(config, &buf->backend, idx);
+}
+
+/*
+ * Check if all space reservation in a buffer have been committed. This helps
+ * knowing if an execution context is nested (for per-cpu buffers only).
+ * This is a very specific ftrace use-case, so we keep this as "internal" API.
+ */
+static inline
+int lib_ring_buffer_reserve_committed(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf,
+ struct channel *chan)
+{
+ unsigned long offset, idx, commit_count;
+
+ CHAN_WARN_ON(chan, config->alloc != RING_BUFFER_ALLOC_PER_CPU);
+ CHAN_WARN_ON(chan, config->sync != RING_BUFFER_SYNC_PER_CPU);
+
+ /*
+ * Read offset and commit count in a loop so they are both read
+ * atomically wrt interrupts. By deal with interrupt concurrency by
+ * restarting both reads if the offset has been pushed. Note that given
+ * we only have to deal with interrupt concurrency here, an interrupt
+ * modifying the commit count will also modify "offset", so it is safe
+ * to only check for offset modifications.
+ */
+ do {
+ offset = v_read(config, &buf->offset);
+ idx = subbuf_index(offset, chan);
+ commit_count = v_read(config, &buf->commit_hot[idx].cc);
+ } while (offset != v_read(config, &buf->offset));
+
+ return ((buf_trunc(offset, chan) >> chan->backend.num_subbuf_order)
+ - (commit_count & chan->commit_count_mask) == 0);
+}
+
+static inline
+void lib_ring_buffer_check_deliver(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf,
+ struct channel *chan,
+ unsigned long offset,
+ unsigned long commit_count,
+ unsigned long idx)
+{
+ unsigned long old_commit_count = commit_count
+ - chan->backend.subbuf_size;
+ u64 tsc;
+
+ /* Check if all commits have been done */
+ if (unlikely((buf_trunc(offset, chan) >> chan->backend.num_subbuf_order)
+ - (old_commit_count & chan->commit_count_mask) == 0)) {
+ /*
+ * If we succeeded at updating cc_sb below, we are the subbuffer
+ * writer delivering the subbuffer. Deals with concurrent
+ * updates of the "cc" value without adding a add_return atomic
+ * operation to the fast path.
+ *
+ * We are doing the delivery in two steps:
+ * - First, we cmpxchg() cc_sb to the new value
+ * old_commit_count + 1. This ensures that we are the only
+ * subbuffer user successfully filling the subbuffer, but we
+ * do _not_ set the cc_sb value to "commit_count" yet.
+ * Therefore, other writers that would wrap around the ring
+ * buffer and try to start writing to our subbuffer would
+ * have to drop records, because it would appear as
+ * non-filled.
+ * We therefore have exclusive access to the subbuffer control
+ * structures. This mutual exclusion with other writers is
+ * crucially important to perform record overruns count in
+ * flight recorder mode locklessly.
+ * - When we are ready to release the subbuffer (either for
+ * reading or for overrun by other writers), we simply set the
+ * cc_sb value to "commit_count" and perform delivery.
+ *
+ * The subbuffer size is least 2 bytes (minimum size: 1 page).
+ * This guarantees that old_commit_count + 1 != commit_count.
+ */
+ if (likely(v_cmpxchg(config, &buf->commit_cold[idx].cc_sb,
+ old_commit_count, old_commit_count + 1)
+ == old_commit_count)) {
+ /*
+ * Start of exclusive subbuffer access. We are
+ * guaranteed to be the last writer in this subbuffer
+ * and any other writer trying to access this subbuffer
+ * in this state is required to drop records.
+ */
+ tsc = config->cb.ring_buffer_clock_read(chan);
+ v_add(config,
+ subbuffer_get_records_count(config,
+ &buf->backend, idx),
+ &buf->records_count);
+ v_add(config,
+ subbuffer_count_records_overrun(config,
+ &buf->backend,
+ idx),
+ &buf->records_overrun);
+ config->cb.buffer_end(buf, tsc, idx,
+ lib_ring_buffer_get_data_size(config,
+ buf,
+ idx));
+
+ /*
+ * Set noref flag and offset for this subbuffer id.
+ * Contains a memory barrier that ensures counter stores
+ * are ordered before set noref and offset.
+ */
+ lib_ring_buffer_set_noref_offset(config, &buf->backend, idx,
+ buf_trunc_val(offset, chan));
+
+ /*
+ * Order set_noref and record counter updates before the
+ * end of subbuffer exclusive access. Orders with
+ * respect to writers coming into the subbuffer after
+ * wrap around, and also order wrt concurrent readers.
+ */
+ smp_mb();
+ /* End of exclusive subbuffer access */
+ v_set(config, &buf->commit_cold[idx].cc_sb,
+ commit_count);
+ lib_ring_buffer_vmcore_check_deliver(config, buf,
+ commit_count, idx);
+
+ /*
+ * RING_BUFFER_WAKEUP_BY_WRITER wakeup is not lock-free.
+ */
+ if (config->wakeup == RING_BUFFER_WAKEUP_BY_WRITER
+ && atomic_long_read(&buf->active_readers)
+ && lib_ring_buffer_poll_deliver(config, buf, chan)) {
+ wake_up_interruptible(&buf->read_wait);
+ wake_up_interruptible(&chan->read_wait);
+ }
+
+ }
+ }
+}
+
+/*
+ * lib_ring_buffer_write_commit_counter
+ *
+ * For flight recording. must be called after commit.
+ * This function increments the subbuffer's commit_seq counter each time the
+ * commit count reaches back the reserve offset (modulo subbuffer size). It is
+ * useful for crash dump.
+ */
+static inline
+void lib_ring_buffer_write_commit_counter(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf,
+ struct channel *chan,
+ unsigned long idx,
+ unsigned long buf_offset,
+ unsigned long commit_count,
+ size_t slot_size)
+{
+ unsigned long offset, commit_seq_old;
+
+ if (config->oops != RING_BUFFER_OOPS_CONSISTENCY)
+ return;
+
+ offset = buf_offset + slot_size;
+
+ /*
+ * subbuf_offset includes commit_count_mask. We can simply
+ * compare the offsets within the subbuffer without caring about
+ * buffer full/empty mismatch because offset is never zero here
+ * (subbuffer header and record headers have non-zero length).
+ */
+ if (unlikely(subbuf_offset(offset - commit_count, chan)))
+ return;
+
+ commit_seq_old = v_read(config, &buf->commit_hot[idx].seq);
+ while ((long) (commit_seq_old - commit_count) < 0)
+ commit_seq_old = v_cmpxchg(config, &buf->commit_hot[idx].seq,
+ commit_seq_old, commit_count);
+}
+
+extern int lib_ring_buffer_create(struct lib_ring_buffer *buf,
+ struct channel_backend *chanb, int cpu);
+extern void lib_ring_buffer_free(struct lib_ring_buffer *buf);
+
+/* Keep track of trap nesting inside ring buffer code */
+DECLARE_PER_CPU(unsigned int, lib_ring_buffer_nesting);
+
+#endif /* _LINUX_RING_BUFFER_FRONTEND_INTERNAL_H */
diff --git a/drivers/staging/lttng/lib/ringbuffer/frontend_types.h b/drivers/staging/lttng/lib/ringbuffer/frontend_types.h
new file mode 100644
index 0000000..5c7437f
--- /dev/null
+++ b/drivers/staging/lttng/lib/ringbuffer/frontend_types.h
@@ -0,0 +1,176 @@
+#ifndef _LINUX_RING_BUFFER_FRONTEND_TYPES_H
+#define _LINUX_RING_BUFFER_FRONTEND_TYPES_H
+
+/*
+ * linux/ringbuffer/frontend_types.h
+ *
+ * (C) Copyright 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Ring Buffer Library Synchronization Header (types).
+ *
+ * Author:
+ * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * See ring_buffer_frontend.c for more information on wait-free algorithms.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/kref.h>
+#include "../../wrapper/ringbuffer/config.h"
+#include "../../wrapper/ringbuffer/backend_types.h"
+#include "../../wrapper/spinlock.h"
+#include "../../lib/prio_heap/lttng_prio_heap.h" /* For per-CPU read-side iterator */
+
+/*
+ * A switch is done during tracing or as a final flush after tracing (so it
+ * won't write in the new sub-buffer).
+ */
+enum switch_mode { SWITCH_ACTIVE, SWITCH_FLUSH };
+
+/* channel-level read-side iterator */
+struct channel_iter {
+ /* Prio heap of buffers. Lowest timestamps at the top. */
+ struct lttng_ptr_heap heap; /* Heap of struct lib_ring_buffer ptrs */
+ struct list_head empty_head; /* Empty buffers linked-list head */
+ int read_open; /* Opened for reading ? */
+ u64 last_qs; /* Last quiescent state timestamp */
+ u64 last_timestamp; /* Last timestamp (for WARN_ON) */
+ int last_cpu; /* Last timestamp cpu */
+ /*
+ * read() file operation state.
+ */
+ unsigned long len_left;
+};
+
+/* channel: collection of per-cpu ring buffers. */
+struct channel {
+ atomic_t record_disabled;
+ unsigned long commit_count_mask; /*
+ * Commit count mask, removing
+ * the MSBs corresponding to
+ * bits used to represent the
+ * subbuffer index.
+ */
+
+ struct channel_backend backend; /* Associated backend */
+
+ unsigned long switch_timer_interval; /* Buffer flush (jiffies) */
+ unsigned long read_timer_interval; /* Reader wakeup (jiffies) */
+ struct notifier_block cpu_hp_notifier; /* CPU hotplug notifier */
+ struct notifier_block tick_nohz_notifier; /* CPU nohz notifier */
+ struct notifier_block hp_iter_notifier; /* hotplug iterator notifier */
+ int cpu_hp_enable:1; /* Enable CPU hotplug notif. */
+ int hp_iter_enable:1; /* Enable hp iter notif. */
+ wait_queue_head_t read_wait; /* reader wait queue */
+ wait_queue_head_t hp_wait; /* CPU hotplug wait queue */
+ int finalized; /* Has channel been finalized */
+ struct channel_iter iter; /* Channel read-side iterator */
+ struct kref ref; /* Reference count */
+};
+
+/* Per-subbuffer commit counters used on the hot path */
+struct commit_counters_hot {
+ union v_atomic cc; /* Commit counter */
+ union v_atomic seq; /* Consecutive commits */
+};
+
+/* Per-subbuffer commit counters used only on cold paths */
+struct commit_counters_cold {
+ union v_atomic cc_sb; /* Incremented _once_ at sb switch */
+};
+
+/* Per-buffer read iterator */
+struct lib_ring_buffer_iter {
+ u64 timestamp; /* Current record timestamp */
+ size_t header_len; /* Current record header length */
+ size_t payload_len; /* Current record payload length */
+
+ struct list_head empty_node; /* Linked list of empty buffers */
+ unsigned long consumed, read_offset, data_size;
+ enum {
+ ITER_GET_SUBBUF = 0,
+ ITER_TEST_RECORD,
+ ITER_NEXT_RECORD,
+ ITER_PUT_SUBBUF,
+ } state;
+ int allocated:1;
+ int read_open:1; /* Opened for reading ? */
+};
+
+/* ring buffer state */
+struct lib_ring_buffer {
+ /* First 32 bytes cache-hot cacheline */
+ union v_atomic offset; /* Current offset in the buffer */
+ struct commit_counters_hot *commit_hot;
+ /* Commit count per sub-buffer */
+ atomic_long_t consumed; /*
+ * Current offset in the buffer
+ * standard atomic access (shared)
+ */
+ atomic_t record_disabled;
+ /* End of first 32 bytes cacheline */
+ union v_atomic last_tsc; /*
+ * Last timestamp written in the buffer.
+ */
+
+ struct lib_ring_buffer_backend backend; /* Associated backend */
+
+ struct commit_counters_cold *commit_cold;
+ /* Commit count per sub-buffer */
+ atomic_long_t active_readers; /*
+ * Active readers count
+ * standard atomic access (shared)
+ */
+ /* Dropped records */
+ union v_atomic records_lost_full; /* Buffer full */
+ union v_atomic records_lost_wrap; /* Nested wrap-around */
+ union v_atomic records_lost_big; /* Events too big */
+ union v_atomic records_count; /* Number of records written */
+ union v_atomic records_overrun; /* Number of overwritten records */
+ wait_queue_head_t read_wait; /* reader buffer-level wait queue */
+ wait_queue_head_t write_wait; /* writer buffer-level wait queue (for metadata only) */
+ int finalized; /* buffer has been finalized */
+ struct timer_list switch_timer; /* timer for periodical switch */
+ struct timer_list read_timer; /* timer for read poll */
+ raw_spinlock_t raw_tick_nohz_spinlock; /* nohz entry lock/trylock */
+ struct lib_ring_buffer_iter iter; /* read-side iterator */
+ unsigned long get_subbuf_consumed; /* Read-side consumed */
+ unsigned long prod_snapshot; /* Producer count snapshot */
+ unsigned long cons_snapshot; /* Consumer count snapshot */
+ int get_subbuf:1; /* Sub-buffer being held by reader */
+ int switch_timer_enabled:1; /* Protected by ring_buffer_nohz_lock */
+ int read_timer_enabled:1; /* Protected by ring_buffer_nohz_lock */
+};
+
+static inline
+void *channel_get_private(struct channel *chan)
+{
+ return chan->backend.priv;
+}
+
+/*
+ * Issue warnings and disable channels upon internal error.
+ * Can receive struct lib_ring_buffer or struct lib_ring_buffer_backend
+ * parameters.
+ */
+#define CHAN_WARN_ON(c, cond) \
+ ({ \
+ struct channel *__chan; \
+ int _____ret = unlikely(cond); \
+ if (_____ret) { \
+ if (__same_type(*(c), struct channel_backend)) \
+ __chan = container_of((void *) (c), \
+ struct channel, \
+ backend); \
+ else if (__same_type(*(c), struct channel)) \
+ __chan = (void *) (c); \
+ else \
+ BUG_ON(1); \
+ atomic_inc(&__chan->record_disabled); \
+ WARN_ON(1); \
+ } \
+ _____ret; \
+ })
+
+#endif /* _LINUX_RING_BUFFER_FRONTEND_TYPES_H */
diff --git a/drivers/staging/lttng/lib/ringbuffer/iterator.h b/drivers/staging/lttng/lib/ringbuffer/iterator.h
new file mode 100644
index 0000000..f2bd50d
--- /dev/null
+++ b/drivers/staging/lttng/lib/ringbuffer/iterator.h
@@ -0,0 +1,70 @@
+#ifndef _LINUX_RING_BUFFER_ITERATOR_H
+#define _LINUX_RING_BUFFER_ITERATOR_H
+
+/*
+ * linux/ringbuffer/iterator.h
+ *
+ * (C) Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Ring buffer and channel iterators.
+ *
+ * Author:
+ * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include "../../wrapper/ringbuffer/backend.h"
+#include "../../wrapper/ringbuffer/frontend.h"
+
+/*
+ * lib_ring_buffer_get_next_record advances the buffer read position to the next
+ * record. It returns either the size of the next record, -EAGAIN if there is
+ * currently no data available, or -ENODATA if no data is available and buffer
+ * is finalized.
+ */
+extern ssize_t lib_ring_buffer_get_next_record(struct channel *chan,
+ struct lib_ring_buffer *buf);
+
+/*
+ * channel_get_next_record advances the buffer read position to the next record.
+ * It returns either the size of the next record, -EAGAIN if there is currently
+ * no data available, or -ENODATA if no data is available and buffer is
+ * finalized.
+ * Returns the current buffer in ret_buf.
+ */
+extern ssize_t channel_get_next_record(struct channel *chan,
+ struct lib_ring_buffer **ret_buf);
+
+/**
+ * read_current_record - copy the buffer current record into dest.
+ * @buf: ring buffer
+ * @dest: destination where the record should be copied
+ *
+ * dest should be large enough to contain the record. Returns the number of
+ * bytes copied.
+ */
+static inline size_t read_current_record(struct lib_ring_buffer *buf, void *dest)
+{
+ return lib_ring_buffer_read(&buf->backend, buf->iter.read_offset,
+ dest, buf->iter.payload_len);
+}
+
+extern int lib_ring_buffer_iterator_open(struct lib_ring_buffer *buf);
+extern void lib_ring_buffer_iterator_release(struct lib_ring_buffer *buf);
+extern int channel_iterator_open(struct channel *chan);
+extern void channel_iterator_release(struct channel *chan);
+
+extern const struct file_operations channel_payload_file_operations;
+extern const struct file_operations lib_ring_buffer_payload_file_operations;
+
+/*
+ * Used internally.
+ */
+int channel_iterator_init(struct channel *chan);
+void channel_iterator_unregister_notifiers(struct channel *chan);
+void channel_iterator_free(struct channel *chan);
+void channel_iterator_reset(struct channel *chan);
+void lib_ring_buffer_iterator_reset(struct lib_ring_buffer *buf);
+
+#endif /* _LINUX_RING_BUFFER_ITERATOR_H */
diff --git a/drivers/staging/lttng/lib/ringbuffer/nohz.h b/drivers/staging/lttng/lib/ringbuffer/nohz.h
new file mode 100644
index 0000000..3c31072
--- /dev/null
+++ b/drivers/staging/lttng/lib/ringbuffer/nohz.h
@@ -0,0 +1,30 @@
+#ifndef _LINUX_RING_BUFFER_NOHZ_H
+#define _LINUX_RING_BUFFER_NOHZ_H
+
+/*
+ * ringbuffer/nohz.h
+ *
+ * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#ifdef CONFIG_LIB_RING_BUFFER
+void lib_ring_buffer_tick_nohz_flush(void);
+void lib_ring_buffer_tick_nohz_stop(void);
+void lib_ring_buffer_tick_nohz_restart(void);
+#else
+static inline void lib_ring_buffer_tick_nohz_flush(void)
+{
+}
+
+static inline void lib_ring_buffer_tick_nohz_stop(void)
+{
+}
+
+static inline void lib_ring_buffer_tick_nohz_restart(void)
+{
+}
+#endif
+
+#endif /* _LINUX_RING_BUFFER_NOHZ_H */
diff --git a/drivers/staging/lttng/lib/ringbuffer/ring_buffer_backend.c b/drivers/staging/lttng/lib/ringbuffer/ring_buffer_backend.c
new file mode 100644
index 0000000..d1b5b8c
--- /dev/null
+++ b/drivers/staging/lttng/lib/ringbuffer/ring_buffer_backend.c
@@ -0,0 +1,854 @@
+/*
+ * ring_buffer_backend.c
+ *
+ * Copyright (C) 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/stddef.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/cpu.h>
+#include <linux/mm.h>
+
+#include "../../wrapper/vmalloc.h" /* for wrapper_vmalloc_sync_all() */
+#include "../../wrapper/ringbuffer/config.h"
+#include "../../wrapper/ringbuffer/backend.h"
+#include "../../wrapper/ringbuffer/frontend.h"
+
+/**
+ * lib_ring_buffer_backend_allocate - allocate a channel buffer
+ * @config: ring buffer instance configuration
+ * @buf: the buffer struct
+ * @size: total size of the buffer
+ * @num_subbuf: number of subbuffers
+ * @extra_reader_sb: need extra subbuffer for reader
+ */
+static
+int lib_ring_buffer_backend_allocate(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_backend *bufb,
+ size_t size, size_t num_subbuf,
+ int extra_reader_sb)
+{
+ struct channel_backend *chanb = &bufb->chan->backend;
+ unsigned long j, num_pages, num_pages_per_subbuf, page_idx = 0;
+ unsigned long subbuf_size, mmap_offset = 0;
+ unsigned long num_subbuf_alloc;
+ struct page **pages;
+ void **virt;
+ unsigned long i;
+
+ num_pages = size >> PAGE_SHIFT;
+ num_pages_per_subbuf = num_pages >> get_count_order(num_subbuf);
+ subbuf_size = chanb->subbuf_size;
+ num_subbuf_alloc = num_subbuf;
+
+ if (extra_reader_sb) {
+ num_pages += num_pages_per_subbuf; /* Add pages for reader */
+ num_subbuf_alloc++;
+ }
+
+ pages = kmalloc_node(ALIGN(sizeof(*pages) * num_pages,
+ 1 << INTERNODE_CACHE_SHIFT),
+ GFP_KERNEL, cpu_to_node(max(bufb->cpu, 0)));
+ if (unlikely(!pages))
+ goto pages_error;
+
+ virt = kmalloc_node(ALIGN(sizeof(*virt) * num_pages,
+ 1 << INTERNODE_CACHE_SHIFT),
+ GFP_KERNEL, cpu_to_node(max(bufb->cpu, 0)));
+ if (unlikely(!virt))
+ goto virt_error;
+
+ bufb->array = kmalloc_node(ALIGN(sizeof(*bufb->array)
+ * num_subbuf_alloc,
+ 1 << INTERNODE_CACHE_SHIFT),
+ GFP_KERNEL, cpu_to_node(max(bufb->cpu, 0)));
+ if (unlikely(!bufb->array))
+ goto array_error;
+
+ for (i = 0; i < num_pages; i++) {
+ pages[i] = alloc_pages_node(cpu_to_node(max(bufb->cpu, 0)),
+ GFP_KERNEL | __GFP_ZERO, 0);
+ if (unlikely(!pages[i]))
+ goto depopulate;
+ virt[i] = page_address(pages[i]);
+ }
+ bufb->num_pages_per_subbuf = num_pages_per_subbuf;
+
+ /* Allocate backend pages array elements */
+ for (i = 0; i < num_subbuf_alloc; i++) {
+ bufb->array[i] =
+ kzalloc_node(ALIGN(
+ sizeof(struct lib_ring_buffer_backend_pages) +
+ sizeof(struct lib_ring_buffer_backend_page)
+ * num_pages_per_subbuf,
+ 1 << INTERNODE_CACHE_SHIFT),
+ GFP_KERNEL, cpu_to_node(max(bufb->cpu, 0)));
+ if (!bufb->array[i])
+ goto free_array;
+ }
+
+ /* Allocate write-side subbuffer table */
+ bufb->buf_wsb = kzalloc_node(ALIGN(
+ sizeof(struct lib_ring_buffer_backend_subbuffer)
+ * num_subbuf,
+ 1 << INTERNODE_CACHE_SHIFT),
+ GFP_KERNEL, cpu_to_node(max(bufb->cpu, 0)));
+ if (unlikely(!bufb->buf_wsb))
+ goto free_array;
+
+ for (i = 0; i < num_subbuf; i++)
+ bufb->buf_wsb[i].id = subbuffer_id(config, 0, 1, i);
+
+ /* Assign read-side subbuffer table */
+ if (extra_reader_sb)
+ bufb->buf_rsb.id = subbuffer_id(config, 0, 1,
+ num_subbuf_alloc - 1);
+ else
+ bufb->buf_rsb.id = subbuffer_id(config, 0, 1, 0);
+
+ /* Assign pages to page index */
+ for (i = 0; i < num_subbuf_alloc; i++) {
+ for (j = 0; j < num_pages_per_subbuf; j++) {
+ CHAN_WARN_ON(chanb, page_idx > num_pages);
+ bufb->array[i]->p[j].virt = virt[page_idx];
+ bufb->array[i]->p[j].page = pages[page_idx];
+ page_idx++;
+ }
+ if (config->output == RING_BUFFER_MMAP) {
+ bufb->array[i]->mmap_offset = mmap_offset;
+ mmap_offset += subbuf_size;
+ }
+ }
+
+ /*
+ * If kmalloc ever uses vmalloc underneath, make sure the buffer pages
+ * will not fault.
+ */
+ wrapper_vmalloc_sync_all();
+ kfree(virt);
+ kfree(pages);
+ return 0;
+
+free_array:
+ for (i = 0; (i < num_subbuf_alloc && bufb->array[i]); i++)
+ kfree(bufb->array[i]);
+depopulate:
+ /* Free all allocated pages */
+ for (i = 0; (i < num_pages && pages[i]); i++)
+ __free_page(pages[i]);
+ kfree(bufb->array);
+array_error:
+ kfree(virt);
+virt_error:
+ kfree(pages);
+pages_error:
+ return -ENOMEM;
+}
+
+int lib_ring_buffer_backend_create(struct lib_ring_buffer_backend *bufb,
+ struct channel_backend *chanb, int cpu)
+{
+ const struct lib_ring_buffer_config *config = chanb->config;
+
+ bufb->chan = container_of(chanb, struct channel, backend);
+ bufb->cpu = cpu;
+
+ return lib_ring_buffer_backend_allocate(config, bufb, chanb->buf_size,
+ chanb->num_subbuf,
+ chanb->extra_reader_sb);
+}
+
+void lib_ring_buffer_backend_free(struct lib_ring_buffer_backend *bufb)
+{
+ struct channel_backend *chanb = &bufb->chan->backend;
+ unsigned long i, j, num_subbuf_alloc;
+
+ num_subbuf_alloc = chanb->num_subbuf;
+ if (chanb->extra_reader_sb)
+ num_subbuf_alloc++;
+
+ kfree(bufb->buf_wsb);
+ for (i = 0; i < num_subbuf_alloc; i++) {
+ for (j = 0; j < bufb->num_pages_per_subbuf; j++)
+ __free_page(bufb->array[i]->p[j].page);
+ kfree(bufb->array[i]);
+ }
+ kfree(bufb->array);
+ bufb->allocated = 0;
+}
+
+void lib_ring_buffer_backend_reset(struct lib_ring_buffer_backend *bufb)
+{
+ struct channel_backend *chanb = &bufb->chan->backend;
+ const struct lib_ring_buffer_config *config = chanb->config;
+ unsigned long num_subbuf_alloc;
+ unsigned int i;
+
+ num_subbuf_alloc = chanb->num_subbuf;
+ if (chanb->extra_reader_sb)
+ num_subbuf_alloc++;
+
+ for (i = 0; i < chanb->num_subbuf; i++)
+ bufb->buf_wsb[i].id = subbuffer_id(config, 0, 1, i);
+ if (chanb->extra_reader_sb)
+ bufb->buf_rsb.id = subbuffer_id(config, 0, 1,
+ num_subbuf_alloc - 1);
+ else
+ bufb->buf_rsb.id = subbuffer_id(config, 0, 1, 0);
+
+ for (i = 0; i < num_subbuf_alloc; i++) {
+ /* Don't reset mmap_offset */
+ v_set(config, &bufb->array[i]->records_commit, 0);
+ v_set(config, &bufb->array[i]->records_unread, 0);
+ bufb->array[i]->data_size = 0;
+ /* Don't reset backend page and virt addresses */
+ }
+ /* Don't reset num_pages_per_subbuf, cpu, allocated */
+ v_set(config, &bufb->records_read, 0);
+}
+
+/*
+ * The frontend is responsible for also calling ring_buffer_backend_reset for
+ * each buffer when calling channel_backend_reset.
+ */
+void channel_backend_reset(struct channel_backend *chanb)
+{
+ struct channel *chan = container_of(chanb, struct channel, backend);
+ const struct lib_ring_buffer_config *config = chanb->config;
+
+ /*
+ * Don't reset buf_size, subbuf_size, subbuf_size_order,
+ * num_subbuf_order, buf_size_order, extra_reader_sb, num_subbuf,
+ * priv, notifiers, config, cpumask and name.
+ */
+ chanb->start_tsc = config->cb.ring_buffer_clock_read(chan);
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+/**
+ * lib_ring_buffer_cpu_hp_callback - CPU hotplug callback
+ * @nb: notifier block
+ * @action: hotplug action to take
+ * @hcpu: CPU number
+ *
+ * Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD)
+ */
+static
+int __cpuinit lib_ring_buffer_cpu_hp_callback(struct notifier_block *nb,
+ unsigned long action,
+ void *hcpu)
+{
+ unsigned int cpu = (unsigned long)hcpu;
+ struct channel_backend *chanb = container_of(nb, struct channel_backend,
+ cpu_hp_notifier);
+ const struct lib_ring_buffer_config *config = chanb->config;
+ struct lib_ring_buffer *buf;
+ int ret;
+
+ CHAN_WARN_ON(chanb, config->alloc == RING_BUFFER_ALLOC_GLOBAL);
+
+ switch (action) {
+ case CPU_UP_PREPARE:
+ case CPU_UP_PREPARE_FROZEN:
+ buf = per_cpu_ptr(chanb->buf, cpu);
+ ret = lib_ring_buffer_create(buf, chanb, cpu);
+ if (ret) {
+ printk(KERN_ERR
+ "ring_buffer_cpu_hp_callback: cpu %d "
+ "buffer creation failed\n", cpu);
+ return NOTIFY_BAD;
+ }
+ break;
+ case CPU_DEAD:
+ case CPU_DEAD_FROZEN:
+ /* No need to do a buffer switch here, because it will happen
+ * when tracing is stopped, or will be done by switch timer CPU
+ * DEAD callback. */
+ break;
+ }
+ return NOTIFY_OK;
+}
+#endif
+
+/**
+ * channel_backend_init - initialize a channel backend
+ * @chanb: channel backend
+ * @name: channel name
+ * @config: client ring buffer configuration
+ * @priv: client private data
+ * @parent: dentry of parent directory, %NULL for root directory
+ * @subbuf_size: size of sub-buffers (> PAGE_SIZE, power of 2)
+ * @num_subbuf: number of sub-buffers (power of 2)
+ *
+ * Returns channel pointer if successful, %NULL otherwise.
+ *
+ * Creates per-cpu channel buffers using the sizes and attributes
+ * specified. The created channel buffer files will be named
+ * name_0...name_N-1. File permissions will be %S_IRUSR.
+ *
+ * Called with CPU hotplug disabled.
+ */
+int channel_backend_init(struct channel_backend *chanb,
+ const char *name,
+ const struct lib_ring_buffer_config *config,
+ void *priv, size_t subbuf_size, size_t num_subbuf)
+{
+ struct channel *chan = container_of(chanb, struct channel, backend);
+ unsigned int i;
+ int ret;
+
+ if (!name)
+ return -EPERM;
+
+ if (!(subbuf_size && num_subbuf))
+ return -EPERM;
+
+ /* Check that the subbuffer size is larger than a page. */
+ if (subbuf_size < PAGE_SIZE)
+ return -EINVAL;
+
+ /*
+ * Make sure the number of subbuffers and subbuffer size are power of 2.
+ */
+ CHAN_WARN_ON(chanb, hweight32(subbuf_size) != 1);
+ CHAN_WARN_ON(chanb, hweight32(num_subbuf) != 1);
+
+ ret = subbuffer_id_check_index(config, num_subbuf);
+ if (ret)
+ return ret;
+
+ chanb->priv = priv;
+ chanb->buf_size = num_subbuf * subbuf_size;
+ chanb->subbuf_size = subbuf_size;
+ chanb->buf_size_order = get_count_order(chanb->buf_size);
+ chanb->subbuf_size_order = get_count_order(subbuf_size);
+ chanb->num_subbuf_order = get_count_order(num_subbuf);
+ chanb->extra_reader_sb =
+ (config->mode == RING_BUFFER_OVERWRITE) ? 1 : 0;
+ chanb->num_subbuf = num_subbuf;
+ strlcpy(chanb->name, name, NAME_MAX);
+ chanb->config = config;
+
+ if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
+ if (!zalloc_cpumask_var(&chanb->cpumask, GFP_KERNEL))
+ return -ENOMEM;
+ }
+
+ if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
+ /* Allocating the buffer per-cpu structures */
+ chanb->buf = alloc_percpu(struct lib_ring_buffer);
+ if (!chanb->buf)
+ goto free_cpumask;
+
+ /*
+ * In case of non-hotplug cpu, if the ring-buffer is allocated
+ * in early initcall, it will not be notified of secondary cpus.
+ * In that off case, we need to allocate for all possible cpus.
+ */
+#ifdef CONFIG_HOTPLUG_CPU
+ /*
+ * buf->backend.allocated test takes care of concurrent CPU
+ * hotplug.
+ * Priority higher than frontend, so we create the ring buffer
+ * before we start the timer.
+ */
+ chanb->cpu_hp_notifier.notifier_call =
+ lib_ring_buffer_cpu_hp_callback;
+ chanb->cpu_hp_notifier.priority = 5;
+ register_hotcpu_notifier(&chanb->cpu_hp_notifier);
+
+ get_online_cpus();
+ for_each_online_cpu(i) {
+ ret = lib_ring_buffer_create(per_cpu_ptr(chanb->buf, i),
+ chanb, i);
+ if (ret)
+ goto free_bufs; /* cpu hotplug locked */
+ }
+ put_online_cpus();
+#else
+ for_each_possible_cpu(i) {
+ ret = lib_ring_buffer_create(per_cpu_ptr(chanb->buf, i),
+ chanb, i);
+ if (ret)
+ goto free_bufs; /* cpu hotplug locked */
+ }
+#endif
+ } else {
+ chanb->buf = kzalloc(sizeof(struct lib_ring_buffer), GFP_KERNEL);
+ if (!chanb->buf)
+ goto free_cpumask;
+ ret = lib_ring_buffer_create(chanb->buf, chanb, -1);
+ if (ret)
+ goto free_bufs;
+ }
+ chanb->start_tsc = config->cb.ring_buffer_clock_read(chan);
+
+ return 0;
+
+free_bufs:
+ if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
+ for_each_possible_cpu(i) {
+ struct lib_ring_buffer *buf = per_cpu_ptr(chanb->buf, i);
+
+ if (!buf->backend.allocated)
+ continue;
+ lib_ring_buffer_free(buf);
+ }
+#ifdef CONFIG_HOTPLUG_CPU
+ put_online_cpus();
+#endif
+ free_percpu(chanb->buf);
+ } else
+ kfree(chanb->buf);
+free_cpumask:
+ if (config->alloc == RING_BUFFER_ALLOC_PER_CPU)
+ free_cpumask_var(chanb->cpumask);
+ return -ENOMEM;
+}
+
+/**
+ * channel_backend_unregister_notifiers - unregister notifiers
+ * @chan: the channel
+ *
+ * Holds CPU hotplug.
+ */
+void channel_backend_unregister_notifiers(struct channel_backend *chanb)
+{
+ const struct lib_ring_buffer_config *config = chanb->config;
+
+ if (config->alloc == RING_BUFFER_ALLOC_PER_CPU)
+ unregister_hotcpu_notifier(&chanb->cpu_hp_notifier);
+}
+
+/**
+ * channel_backend_free - destroy the channel
+ * @chan: the channel
+ *
+ * Destroy all channel buffers and frees the channel.
+ */
+void channel_backend_free(struct channel_backend *chanb)
+{
+ const struct lib_ring_buffer_config *config = chanb->config;
+ unsigned int i;
+
+ if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
+ for_each_possible_cpu(i) {
+ struct lib_ring_buffer *buf = per_cpu_ptr(chanb->buf, i);
+
+ if (!buf->backend.allocated)
+ continue;
+ lib_ring_buffer_free(buf);
+ }
+ free_cpumask_var(chanb->cpumask);
+ free_percpu(chanb->buf);
+ } else {
+ struct lib_ring_buffer *buf = chanb->buf;
+
+ CHAN_WARN_ON(chanb, !buf->backend.allocated);
+ lib_ring_buffer_free(buf);
+ kfree(buf);
+ }
+}
+
+/**
+ * lib_ring_buffer_write - write data to a ring_buffer buffer.
+ * @bufb : buffer backend
+ * @offset : offset within the buffer
+ * @src : source address
+ * @len : length to write
+ * @pagecpy : page size copied so far
+ */
+void _lib_ring_buffer_write(struct lib_ring_buffer_backend *bufb, size_t offset,
+ const void *src, size_t len, ssize_t pagecpy)
+{
+ struct channel_backend *chanb = &bufb->chan->backend;
+ const struct lib_ring_buffer_config *config = chanb->config;
+ size_t sbidx, index;
+ struct lib_ring_buffer_backend_pages *rpages;
+ unsigned long sb_bindex, id;
+
+ do {
+ len -= pagecpy;
+ src += pagecpy;
+ offset += pagecpy;
+ sbidx = offset >> chanb->subbuf_size_order;
+ index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
+
+ /*
+ * Underlying layer should never ask for writes across
+ * subbuffers.
+ */
+ CHAN_WARN_ON(chanb, offset >= chanb->buf_size);
+
+ pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
+ id = bufb->buf_wsb[sbidx].id;
+ sb_bindex = subbuffer_id_get_index(config, id);
+ rpages = bufb->array[sb_bindex];
+ CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE
+ && subbuffer_id_is_noref(config, id));
+ lib_ring_buffer_do_copy(config,
+ rpages->p[index].virt
+ + (offset & ~PAGE_MASK),
+ src, pagecpy);
+ } while (unlikely(len != pagecpy));
+}
+EXPORT_SYMBOL_GPL(_lib_ring_buffer_write);
+
+