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Commit c84a83e2 authored by Jens Axboe's avatar Jens Axboe
Browse files

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



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: default avatarJens Axboe <axboe@kernel.dk>
parent e3daab6c

kernel/smp.c

+5 −1
Original line number Diff line number Diff line
@@ -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);