smp: don't warn about csd->flags having CSD_FLAG_LOCK cleared for !wait (c84a83e2) · Commits · 戴 / test

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>

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);

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