From: Asias He <asias@redhat.com>
To: Tim Gardner <rtg.canonical@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>, Tejun Heo <tj@kernel.org>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
tim.gardner@canonical.com
Subject: Re: [PATCH V3] block: Mitigate lock unbalance caused by lock switching
Date: Wed, 30 May 2012 14:28:05 +0800 [thread overview]
Message-ID: <4FC5BDF5.2040000@redhat.com> (raw)
In-Reply-To: <4FC4D2F2.2070309@gmail.com>
On 05/29/2012 09:45 PM, Tim Gardner wrote:
> On 05/28/2012 07:39 PM, Asias He wrote:
>
> <snip>
>
>> @@ -440,6 +435,11 @@ void blk_cleanup_queue(struct request_queue *q)
>> del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer);
>> blk_sync_queue(q);
>>
>> + spin_lock_irq(lock);
>> + if (q->queue_lock !=&q->__queue_lock)
>> + q->queue_lock =&q->__queue_lock;
>> + spin_unlock_irq(lock);
>> +
>
> Isn't the 'if' clause superfluous ? You could just do the assignment, e.g.,
>
> + spin_lock_irq(lock);
> + q->queue_lock =&q->__queue_lock;
> + spin_unlock_irq(lock);
Well, this saves a if clause but adds an unnecessary assignment if the
lock is already internal lock.
--
Asias
next prev parent reply other threads:[~2012-05-30 6:28 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-25 2:10 [PATCH] block: Fix lock unbalance caused by lock disconnect Asias He
2012-05-28 0:07 ` Tejun Heo
2012-05-28 2:15 ` Asias He
2012-05-28 10:20 ` Tejun Heo
2012-05-29 1:49 ` Asias He
2012-06-01 9:28 ` Michael S. Tsirkin
2012-05-28 2:20 ` [PATCH v2] block: Mitigate " Asias He
2012-05-28 10:22 ` Tejun Heo
2012-05-29 1:39 ` [PATCH V3] block: Mitigate lock unbalance caused by lock switching Asias He
2012-05-29 1:39 ` [PATCH] " Asias He
2012-05-29 1:41 ` [PATCH V3] " Tejun Heo
2012-05-29 13:45 ` Tim Gardner
2012-05-30 6:28 ` Asias He [this message]
2012-05-30 6:28 ` Tejun Heo
2012-05-30 6:50 ` Asias He
2012-06-01 9:31 ` Jens Axboe
2012-06-06 2:12 ` Asias He
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