From: Paolo Bonzini <pbonzini@redhat.com>
Date: Fri, 7 Nov 2014 22:03:59 +0000 (+0100)
Subject: blk_mq: call preempt_disable/enable in blk_mq_run_hw_queue, and only if needed
X-Git-Tag: omap-for-v3.19/fixes-rc1~95^2~20
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=398205b8391b208f0034a392242867b28ad8af3d;p=pandora-kernel.git

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>
---

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