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authorIngo Molnar <mingo@kernel.org>2013-01-24 12:48:41 +0100
committerIngo Molnar <mingo@kernel.org>2013-01-24 12:48:41 +0100
commit786133f6e8ff94aaa78cd6b7844d04c227098327 (patch)
treebe5922c90ec74267bf068987e4de14a6436d04de /kernel/irq_work.c
parentbefddb21c845f8fb49e637997891ef97c6a869dc (diff)
parent6147a9d8070e1c9d16d57eb53a14942b95b28dc4 (diff)
downloadop-kernel-dev-786133f6e8ff94aaa78cd6b7844d04c227098327.zip
op-kernel-dev-786133f6e8ff94aaa78cd6b7844d04c227098327.tar.gz
Merge branch 'core/irq_work' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into irq/core
irq_work fixes and cleanups, in preparation for full dyntics support. Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/irq_work.c')
-rw-r--r--kernel/irq_work.c21
1 files changed, 15 insertions, 6 deletions
diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index 1588e3b..64eddd5 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -34,15 +34,21 @@ static DEFINE_PER_CPU(struct llist_head, irq_work_list);
*/
static bool irq_work_claim(struct irq_work *work)
{
- unsigned long flags, nflags;
+ unsigned long flags, oflags, nflags;
+ /*
+ * Start with our best wish as a premise but only trust any
+ * flag value after cmpxchg() result.
+ */
+ flags = work->flags & ~IRQ_WORK_PENDING;
for (;;) {
- flags = work->flags;
- if (flags & IRQ_WORK_PENDING)
- return false;
nflags = flags | IRQ_WORK_FLAGS;
- if (cmpxchg(&work->flags, flags, nflags) == flags)
+ oflags = cmpxchg(&work->flags, flags, nflags);
+ if (oflags == flags)
break;
+ if (oflags & IRQ_WORK_PENDING)
+ return false;
+ flags = oflags;
cpu_relax();
}
@@ -119,8 +125,11 @@ void irq_work_run(void)
/*
* Clear the PENDING bit, after this point the @work
* can be re-used.
+ * Make it immediately visible so that other CPUs trying
+ * to claim that work don't rely on us to handle their data
+ * while we are in the middle of the func.
*/
- work->flags = IRQ_WORK_BUSY;
+ xchg(&work->flags, IRQ_WORK_BUSY);
work->func(work);
/*
* Clear the BUSY bit and return to the free state if
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