From: Robert Hancock <hancockr@shaw.ca>
To: Larry Finger <Larry.Finger@lwfinger.net>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: Re: Question regarding mutex locking
Date: Tue, 27 Nov 2007 22:53:20 -0600 [thread overview]
Message-ID: <474CF440.2000001@shaw.ca> (raw)
In-Reply-To: <fa.C9TdvYAhY8SablNc39IpD8WDnNM@ifi.uio.no>
Larry Finger wrote:
> If a particular routine needs to lock a mutex, but it may be entered with that mutex already locked,
> would the following code be SMP safe?
>
> hold_lock = mutex_trylock()
>
> ..
>
> if (hold_lock)
> mutex_unlock()
Not if another task could be acquiring that lock at the same time, which
is probably the case, otherwise you wouldn't need the mutex. In other
words, if you're going to do this, you might as well toss the mutex
entirely as it's about the same effect..
--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/
next parent reply other threads:[~2007-11-28 4:53 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <fa.C9TdvYAhY8SablNc39IpD8WDnNM@ifi.uio.no>
2007-11-28 4:53 ` Robert Hancock [this message]
2007-11-28 5:19 ` Question regarding mutex locking Larry Finger
2007-11-29 2:34 ` David Schwartz
2007-11-29 7:56 ` Jarek Poplawski
2007-11-28 4:37 Larry Finger
2007-11-28 8:10 ` Matthias Kaehlcke
2007-11-28 14:46 ` Larry Finger
2007-11-28 15:00 ` Matthias Kaehlcke
2007-11-28 15:22 ` Andreas Schwab
2007-11-28 15:41 ` Larry Finger
2007-11-28 22:45 ` Jarek Poplawski
2007-11-28 22:56 ` Jarek Poplawski
2007-11-28 23:07 ` Jarek Poplawski
2007-11-28 23:33 ` Stephen Hemminger
2007-11-29 6:40 ` Jarek Poplawski
2007-11-30 1:13 ` Bryan O'Sullivan
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