From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Sean MacLennan <seanm@seanm.ca>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: WARNING: mutexes are preferred for single holder semaphores
Date: Mon, 05 May 2008 13:38:39 +1000 [thread overview]
Message-ID: <1209958719.21644.32.camel@pasglop> (raw)
In-Reply-To: <20080504204104.7eea7618@lappy.seanm.ca>
On Sun, 2008-05-04 at 20:41 -0400, Sean MacLennan wrote:
> This is a bit OT, but I got the warning in the subject from
> checkpatch.pl for a piece of code. The code *is* using a mutex. Does it
> actually mean I shouldn't use a mutex?
>
> The code declares a global mutex:
>
> static DECLARE_MUTEX(list_lock);
>
> The odds of two accesses to the list_lock at the same time are zero.
> But it would be Very Bad(tm) if it did happen. Since the odds of
> contention are near zero, the cost of the mutex is near zero, so I put
> it in.
>
> I think I can safely ignore the warning, but I want to make sure....
Show us the code... It could be a bug in checkpatch or you using
the wrong functions somewhere ...
Ben.
next prev parent reply other threads:[~2008-05-05 3:38 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-05 0:41 WARNING: mutexes are preferred for single holder semaphores Sean MacLennan
2008-05-05 1:06 ` Michael Ellerman
2008-05-05 1:31 ` Sean MacLennan
2008-05-05 2:13 ` Paul Mackerras
2008-05-05 6:01 ` Christoph Hellwig
2008-05-05 3:38 ` Benjamin Herrenschmidt [this message]
2008-05-05 4:40 ` Sean MacLennan
2008-05-07 14:36 ` All your drivers are belong to us [was WARNING: mutexes are preferred for single holder semaphores] Detlev Zundel
2008-05-07 21:42 ` All your drivers are belong to us [was WARNING: mutexes are preferredfor " Sean MacLennan
2008-05-08 0:49 ` Josh Boyer
2008-05-08 4:41 ` Sean MacLennan
2008-05-08 13:28 ` All your drivers are belong to us Detlev Zundel
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