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smp: don't warn about csd->flags having CSD_FLAG_LOCK cleared for !wait

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blk-mq reuses the request potentially immediately, since the most
cache hot is always given out first. This means that rq->csd could
be reused between csd->func() being called and csd_unlock() being
called. This isn't a problem, since we never use wait == 1 for
the smp call function. Add CSD_FLAG_WAIT to be able to tell the
difference, retaining the warning for other cases.

Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2013-05-17 09:58:43 +02:00
parent e3daab6ce4
commit c84a83e2aa
1 changed files with 5 additions and 1 deletions
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6
kernel/smp.c
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@ -18,6 +18,7 @@
#ifdef CONFIG_USE_GENERIC_SMP_HELPERS
enum {
CSD_FLAG_LOCK = 0x01,
CSD_FLAG_WAIT = 0x02,
};
struct call_function_data {
@ -124,7 +125,7 @@ static void csd_lock(struct call_single_data *csd)
static void csd_unlock(struct call_single_data *csd)
{
WARN_ON(!(csd->flags & CSD_FLAG_LOCK));
WARN_ON((csd->flags & CSD_FLAG_WAIT) && !(csd->flags & CSD_FLAG_LOCK));
/*
* ensure we're all done before releasing data:
@ -146,6 +147,9 @@ void generic_exec_single(int cpu, struct call_single_data *csd, int wait)
unsigned long flags;
int ipi;
if (wait)
csd->flags |= CSD_FLAG_WAIT;
raw_spin_lock_irqsave(&dst->lock, flags);
ipi = list_empty(&dst->list);
list_add_tail(&csd->list, &dst->list);