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blk-mq: Don't disable preemption around __blk_mq_run_hw_queue(). 

__blk_mq_delay_run_hw_queue() disables preemption to get a stable
current CPU number and then invokes __blk_mq_run_hw_queue() if the CPU
number is part the mask.

__blk_mq_run_hw_queue() acquires a spin_lock_t which is a sleeping lock
on PREEMPT_RT and can't be acquired with disabled preemption.

It is not required for correctness to invoke __blk_mq_run_hw_queue() on
a CPU matching hctx->cpumask. Both (async and direct requests) can run
on a CPU not matching hctx->cpumask.

The CPU mask without disabling preemption and invoking
__blk_mq_run_hw_queue().

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/YrLSEiNvagKJaDs5@linutronix.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Sebastian Andrzej Siewior 2022-06-22 10:25:54 +02:00 committed by Jens Axboe
parent 1d87be8212
commit 3c8f9da41e
1 changed files with 1 additions and 5 deletions
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6
block/blk-mq.c
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@ -2085,14 +2085,10 @@ static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
return;
if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
int cpu = get_cpu();
if (cpumask_test_cpu(cpu, hctx->cpumask)) {
if (cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask)) {
__blk_mq_run_hw_queue(hctx);
put_cpu();
return;
}
put_cpu();
}
kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work,