From: Andrew Morton <akpm@linux-foundation.org>
To: Jerry Cooperstein <jerry.cooperstein@charter.net>
Cc: linux-kernel@vger.kernel.org
Subject: Re: mutex_unlock() in interrupt context
Date: Tue, 17 Jul 2007 00:01:38 -0700 [thread overview]
Message-ID: <20070717000138.0d255ed5.akpm@linux-foundation.org> (raw)
In-Reply-To: <46981580.5000008@charter.net>
On Fri, 13 Jul 2007 19:14:56 -0500 Jerry Cooperstein <jerry.cooperstein@charter.net> wrote:
> kernel/mutex.c says about mutex_unlock():
>
> * This function must not be used in interrupt context.
>
> However I have done some simple test cases that show
> it works without complaint. Now I understand that one
> shouldn't do this for good reasons. So is this a
> good coding practice rule, but something that
> could appear in sloppy or poorly designed code?
>
mutex_unlock() must be called by the process which did the mutex_lock().
Doing the mutex_unlock() from an interrupt will cause warnings when run
with debugging enabled. You should run with debugging enabled when doing
any development.
Also, mutex_unlock() takes a mutex-internal spinlock in a non-irq-safe
fashion - if the timing is right, your mutex_unlock() in IRQ context will
deadlock.
prev parent reply other threads:[~2007-07-17 7:02 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-13 22:35 [-mm PATCH 0/2] 74% decrease in dispatched writes, stripe-queue take3 Dan Williams
2007-07-13 22:35 ` [-mm PATCH 1/2] raid5: add the stripe_queue object for tracking raid io requests (take2) Dan Williams
2007-07-13 22:35 ` [-mm PATCH 2/2] raid5: use stripe_queues to prioritize the "most deserving" requests (take3) Dan Williams
2007-07-13 22:54 ` [-mm PATCH 0/2] 74% decrease in dispatched writes, stripe-queue take3 Andrew Morton
2007-07-13 22:57 ` Williams, Dan J
2007-07-13 22:57 ` Williams, Dan J
2007-07-13 23:01 ` Andrew Morton
2007-07-13 23:01 ` Andrew Morton
2007-07-13 23:28 ` Williams, Dan J
2007-07-13 23:28 ` Williams, Dan J
2007-07-14 0:01 ` Andrew Morton
2007-07-14 0:01 ` Andrew Morton
2007-07-14 0:14 ` mutex_unlock() in interrupt context Jerry Cooperstein
2007-07-17 7:01 ` Andrew Morton [this message]
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