From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Mon, 8 Oct 2012 17:37:22 +0000 (-0700)
Subject: 3.0-stable patches
X-Git-Tag: v3.0.46~52
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=f7528cf44d9b18b4b7a3a439e4f6267a4e40ef7a;p=thirdparty%2Fkernel%2Fstable-queue.git

3.0-stable patches

added patches:
	workqueue-add-missing-smp_wmb-in-process_one_work.patch
---

diff --git a/queue-3.0/series b/queue-3.0/series
index 207b467e5ae..2f14e489d0c 100644
--- a/queue-3.0/series
+++ b/queue-3.0/series
@@ -6,3 +6,4 @@ pci-acpiphp-check-whether-_adr-evaluation-succeeded.patch
 lib-gcd.c-prevent-possible-div-by-0.patch
 kernel-sys.c-call-disable_nonboot_cpus-in-kernel_restart.patch
 drivers-scsi-atp870u.c-fix-bad-use-of-udelay.patch
+workqueue-add-missing-smp_wmb-in-process_one_work.patch
diff --git a/queue-3.0/workqueue-add-missing-smp_wmb-in-process_one_work.patch b/queue-3.0/workqueue-add-missing-smp_wmb-in-process_one_work.patch
new file mode 100644
index 00000000000..f93677b2c07
--- /dev/null
+++ b/queue-3.0/workqueue-add-missing-smp_wmb-in-process_one_work.patch
@@ -0,0 +1,44 @@
+From 959d1af8cffc8fd38ed53e8be1cf4ab8782f9c00 Mon Sep 17 00:00:00 2001
+From: Tejun Heo <tj@kernel.org>
+Date: Fri, 3 Aug 2012 10:30:45 -0700
+Subject: workqueue: add missing smp_wmb() in process_one_work()
+
+From: Tejun Heo <tj@kernel.org>
+
+commit 959d1af8cffc8fd38ed53e8be1cf4ab8782f9c00 upstream.
+
+WORK_STRUCT_PENDING is used to claim ownership of a work item and
+process_one_work() releases it before starting execution.  When
+someone else grabs PENDING, all pre-release updates to the work item
+should be visible and all updates made by the new owner should happen
+afterwards.
+
+Grabbing PENDING uses test_and_set_bit() and thus has a full barrier;
+however, clearing doesn't have a matching wmb.  Given the preceding
+spin_unlock and use of clear_bit, I don't believe this can be a
+problem on an actual machine and there hasn't been any related report
+but it still is theretically possible for clear_pending to permeate
+upwards and happen before work->entry update.
+
+Add an explicit smp_wmb() before work_clear_pending().
+
+Signed-off-by: Tejun Heo <tj@kernel.org>
+Cc: Oleg Nesterov <oleg@redhat.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ kernel/workqueue.c |    2 ++
+ 1 file changed, 2 insertions(+)
+
+--- a/kernel/workqueue.c
++++ b/kernel/workqueue.c
+@@ -1868,7 +1868,9 @@ __acquires(&gcwq->lock)
+ 
+ 	spin_unlock_irq(&gcwq->lock);
+ 
++	smp_wmb();	/* paired with test_and_set_bit(PENDING) */
+ 	work_clear_pending(work);
++
+ 	lock_map_acquire_read(&cwq->wq->lockdep_map);
+ 	lock_map_acquire(&lockdep_map);
+ 	trace_workqueue_execute_start(work);