fs-block-preempt-rt-support.patch

From d1f7b1468342aaa0b28123a04a329e0e77ad0311 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Fri, 3 Jul 2009 08:30:12 -0500
Subject: [PATCH] fs/block: preempt-rt support

commit e97977e5171636cba43ae9d30f00cb82e175511b in tip.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/block/blk-core.c b/block/blk-core.c
index d1a9a0a..f776d0e 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -202,7 +202,7 @@ EXPORT_SYMBOL(blk_dump_rq_flags);
  */
 void blk_plug_device(struct request_queue *q)
 {
-	WARN_ON(!irqs_disabled());
+	WARN_ON_NONRT(!irqs_disabled());
 
 	/*
 	 * don't plug a stopped queue, it must be paired with blk_start_queue()
@@ -242,7 +242,7 @@ EXPORT_SYMBOL(blk_plug_device_unlocked);
  */
 int blk_remove_plug(struct request_queue *q)
 {
-	WARN_ON(!irqs_disabled());
+	WARN_ON_NONRT(!irqs_disabled());
 
 	if (!queue_flag_test_and_clear(QUEUE_FLAG_PLUGGED, q))
 		return 0;
@@ -334,7 +334,7 @@ EXPORT_SYMBOL(blk_unplug);
  **/
 void blk_start_queue(struct request_queue *q)
 {
-	WARN_ON(!irqs_disabled());
+	WARN_ON_NONRT(!irqs_disabled());
 
 	queue_flag_clear(QUEUE_FLAG_STOPPED, q);
 	__blk_run_queue(q);
diff --git a/fs/dcache.c b/fs/dcache.c
index 953173a..116fd33 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -727,8 +727,9 @@ void shrink_dcache_for_umount(struct super_block *sb)
 {
 	struct dentry *dentry;
 
-	if (down_read_trylock(&sb->s_umount))
-		BUG();
+// -rt: this might succeed there ...
+//	if (down_read_trylock(&sb->s_umount))
+//		BUG();
 
 	dentry = sb->s_root;
 	sb->s_root = NULL;
diff --git a/fs/exec.c b/fs/exec.c
index cce6bbd..9192f7e 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -55,6 +55,7 @@
 #include <linux/fsnotify.h>
 #include <linux/fs_struct.h>
 #include <linux/pipe_fs_i.h>
+#include <linux/delay.h>
 
 #include <asm/uaccess.h>
 #include <asm/mmu_context.h>
@@ -734,10 +735,12 @@ static int exec_mmap(struct mm_struct *mm)
 		}
 	}
 	task_lock(tsk);
+	local_irq_disable();
 	active_mm = tsk->active_mm;
+	activate_mm(active_mm, mm);
 	tsk->mm = mm;
 	tsk->active_mm = mm;
-	activate_mm(active_mm, mm);
+	local_irq_enable();
 	task_unlock(tsk);
 	arch_pick_mmap_layout(mm);
 	if (old_mm) {
diff --git a/fs/file.c b/fs/file.c
index 87e1290..b08281f 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -103,14 +103,15 @@ void free_fdtable_rcu(struct rcu_head *rcu)
 		kfree(fdt->open_fds);
 		kfree(fdt);
 	} else {
-		fddef = &get_cpu_var(fdtable_defer_list);
+
+		fddef = &per_cpu(fdtable_defer_list, raw_smp_processor_id());
+
 		spin_lock(&fddef->lock);
 		fdt->next = fddef->next;
 		fddef->next = fdt;
 		/* vmallocs are handled from the workqueue context */
 		schedule_work(&fddef->wq);
 		spin_unlock(&fddef->lock);
-		put_cpu_var(fdtable_defer_list);
 	}
 }
 
diff --git a/fs/pipe.c b/fs/pipe.c
index 37ba29f..a9dcf21 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -434,8 +434,14 @@ redo:
 		wake_up_interruptible_sync(&pipe->wait);
 		kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
 	}
+	/*
+	 * Hack: we turn off atime updates for -RT kernels.
+	 * Who uses them on pipes anyway?
+	 */
+#ifndef CONFIG_PREEMPT_RT
 	if (ret > 0)
 		file_accessed(filp);
+#endif
 	return ret;
 }
 
@@ -607,8 +613,14 @@ out:
 		wake_up_interruptible_sync(&pipe->wait);
 		kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 	}
+	/*
+	 * Hack: we turn off atime updates for -RT kernels.
+	 * Who uses them on pipes anyway?
+	 */
+#ifndef CONFIG_PREEMPT_RT
 	if (ret > 0)
 		file_update_time(filp);
+#endif
 	return ret;
 }
 
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index f277c4a..da4409e 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -138,8 +138,10 @@ static void *m_start(struct seq_file *m, loff_t *pos)
 	vma = NULL;
 	if ((unsigned long)l < mm->map_count) {
 		vma = mm->mmap;
-		while (l-- && vma)
+		while (l-- && vma) {
 			vma = vma->vm_next;
+			cond_resched();
+		}
 		goto out;
 	}
 
-- 
1.7.1.1