tree 2b7ce3ddc4029a15f7efbe4bb1e5711b9607dfc3
parent 9c6ac78eb3521c5937b2dd8a7d1b300f41092f45
author Paolo Bonzini <pbonzini@redhat.com> 1415397839 +0100
committer Jens Axboe <axboe@fb.com> 1415729087 -0700

blk_mq: call preempt_disable/enable in blk_mq_run_hw_queue, and only if needed

preempt_disable/enable surrounds every call to blk_mq_run_hw_queue,
except the one in blk-flush.c.  In fact that one is always asynchronous,
and it does not need smp_processor_id().

We can do the same for all other calls, avoiding preempt_disable when
async is true.  This avoids peppering blk-mq.c with preemption-disabled
regions.

Cc: Jens Axboe <axboe@kernel.dk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Clark Williams <williams@redhat.com>
Tested-by: Clark Williams <williams@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>