| /* |
| * Copyright (c) 2006 Oracle. All rights reserved. |
| * |
| * This software is available to you under a choice of one of two |
| * licenses. You may choose to be licensed under the terms of the GNU |
| * General Public License (GPL) Version 2, available from the file |
| * COPYING in the main directory of this source tree, or the |
| * OpenIB.org BSD license below: |
| * |
| * Redistribution and use in source and binary forms, with or |
| * without modification, are permitted provided that the following |
| * conditions are met: |
| * |
| * - Redistributions of source code must retain the above |
| * copyright notice, this list of conditions and the following |
| * disclaimer. |
| * |
| * - Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following |
| * disclaimer in the documentation and/or other materials |
| * provided with the distribution. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
| * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
| * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND |
| * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS |
| * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN |
| * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN |
| * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
| * SOFTWARE. |
| * |
| */ |
| #include <linux/highmem.h> |
| |
| #include "rds.h" |
| |
| struct rds_page_remainder { |
| struct page *r_page; |
| unsigned long r_offset; |
| }; |
| |
| DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder, rds_page_remainders); |
| |
| /* |
| * returns 0 on success or -errno on failure. |
| * |
| * We don't have to worry about flush_dcache_page() as this only works |
| * with private pages. If, say, we were to do directed receive to pinned |
| * user pages we'd have to worry more about cache coherence. (Though |
| * the flush_dcache_page() in get_user_pages() would probably be enough). |
| */ |
| int rds_page_copy_user(struct page *page, unsigned long offset, |
| void __user *ptr, unsigned long bytes, |
| int to_user) |
| { |
| unsigned long ret; |
| void *addr; |
| |
| addr = kmap(page); |
| if (to_user) { |
| rds_stats_add(s_copy_to_user, bytes); |
| ret = copy_to_user(ptr, addr + offset, bytes); |
| } else { |
| rds_stats_add(s_copy_from_user, bytes); |
| ret = copy_from_user(addr + offset, ptr, bytes); |
| } |
| kunmap(page); |
| |
| return ret ? -EFAULT : 0; |
| } |
| EXPORT_SYMBOL_GPL(rds_page_copy_user); |
| |
| /* |
| * Message allocation uses this to build up regions of a message. |
| * |
| * @bytes - the number of bytes needed. |
| * @gfp - the waiting behaviour of the allocation |
| * |
| * @gfp is always ored with __GFP_HIGHMEM. Callers must be prepared to |
| * kmap the pages, etc. |
| * |
| * If @bytes is at least a full page then this just returns a page from |
| * alloc_page(). |
| * |
| * If @bytes is a partial page then this stores the unused region of the |
| * page in a per-cpu structure. Future partial-page allocations may be |
| * satisfied from that cached region. This lets us waste less memory on |
| * small allocations with minimal complexity. It works because the transmit |
| * path passes read-only page regions down to devices. They hold a page |
| * reference until they are done with the region. |
| */ |
| int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes, |
| gfp_t gfp) |
| { |
| struct rds_page_remainder *rem; |
| unsigned long flags; |
| struct page *page; |
| int ret; |
| |
| gfp |= __GFP_HIGHMEM; |
| |
| /* jump straight to allocation if we're trying for a huge page */ |
| if (bytes >= PAGE_SIZE) { |
| page = alloc_page(gfp); |
| if (page == NULL) { |
| ret = -ENOMEM; |
| } else { |
| sg_set_page(scat, page, PAGE_SIZE, 0); |
| ret = 0; |
| } |
| goto out; |
| } |
| |
| rem = &per_cpu(rds_page_remainders, get_cpu()); |
| local_irq_save(flags); |
| |
| while (1) { |
| /* avoid a tiny region getting stuck by tossing it */ |
| if (rem->r_page && bytes > (PAGE_SIZE - rem->r_offset)) { |
| rds_stats_inc(s_page_remainder_miss); |
| __free_page(rem->r_page); |
| rem->r_page = NULL; |
| } |
| |
| /* hand out a fragment from the cached page */ |
| if (rem->r_page && bytes <= (PAGE_SIZE - rem->r_offset)) { |
| sg_set_page(scat, rem->r_page, bytes, rem->r_offset); |
| get_page(sg_page(scat)); |
| |
| if (rem->r_offset != 0) |
| rds_stats_inc(s_page_remainder_hit); |
| |
| rem->r_offset += bytes; |
| if (rem->r_offset == PAGE_SIZE) { |
| __free_page(rem->r_page); |
| rem->r_page = NULL; |
| } |
| ret = 0; |
| break; |
| } |
| |
| /* alloc if there is nothing for us to use */ |
| local_irq_restore(flags); |
| put_cpu(); |
| |
| page = alloc_page(gfp); |
| |
| rem = &per_cpu(rds_page_remainders, get_cpu()); |
| local_irq_save(flags); |
| |
| if (page == NULL) { |
| ret = -ENOMEM; |
| break; |
| } |
| |
| /* did someone race to fill the remainder before us? */ |
| if (rem->r_page) { |
| __free_page(page); |
| continue; |
| } |
| |
| /* otherwise install our page and loop around to alloc */ |
| rem->r_page = page; |
| rem->r_offset = 0; |
| } |
| |
| local_irq_restore(flags); |
| put_cpu(); |
| out: |
| rdsdebug("bytes %lu ret %d %p %u %u\n", bytes, ret, |
| ret ? NULL : sg_page(scat), ret ? 0 : scat->offset, |
| ret ? 0 : scat->length); |
| return ret; |
| } |
| |
| static int rds_page_remainder_cpu_notify(struct notifier_block *self, |
| unsigned long action, void *hcpu) |
| { |
| struct rds_page_remainder *rem; |
| long cpu = (long)hcpu; |
| |
| rem = &per_cpu(rds_page_remainders, cpu); |
| |
| rdsdebug("cpu %ld action 0x%lx\n", cpu, action); |
| |
| switch (action) { |
| case CPU_DEAD: |
| if (rem->r_page) |
| __free_page(rem->r_page); |
| rem->r_page = NULL; |
| break; |
| } |
| |
| return 0; |
| } |
| |
| static struct notifier_block rds_page_remainder_nb = { |
| .notifier_call = rds_page_remainder_cpu_notify, |
| }; |
| |
| void rds_page_exit(void) |
| { |
| int i; |
| |
| for_each_possible_cpu(i) |
| rds_page_remainder_cpu_notify(&rds_page_remainder_nb, |
| (unsigned long)CPU_DEAD, |
| (void *)(long)i); |
| } |