From: Arnd Bergmann <arnd@arndb.de>
To: Daniel Walker <dwalker@codeaurora.org>
Cc: Hillf Danton <dhillf@gmail.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v0] add nano semaphore in kernel
Date: Wed, 29 Dec 2010 12:47:27 +0100 [thread overview]
Message-ID: <201012291247.27663.arnd@arndb.de> (raw)
In-Reply-To: <1293551490.24601.10.camel@m0nster>
On Tuesday 28 December 2010 16:51:30 Daniel Walker wrote:
> We for sure don't want new semaphores, or new semaphore usage in the
> kernel ..
Yes. I once even tried unifying the semaphore and rwsem implementation,
but gave up on that for a number of reasons.
> It should also be noted that the rtmutex (kernel/rtmutex.c) already has
> this capability. Although I don't think you can use an rtmutex from
> inside the kernel.
I wasn't aware we had already grown another one ;-)
AFAICT, you can only use it inside of the kernel, but it's very
specific and I wouldn't recommend using it unless a regular mutex
cannot be used for some reason. The only user besides the futex
code seems to be the i2c layer at this moment.
> If you really want this you should look into the rtmutex, and the
> regular mutex API's .
If Hillf relies on counting semaphores, that won't work, but very
few such users exist in code outside of textbooks.
Arnd
next prev parent reply other threads:[~2010-12-29 11:48 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-26 5:13 [PATCH v0] add nano semaphore in kernel Hillf Danton
2010-12-26 6:46 ` Rakib Mullick
2010-12-26 7:04 ` Hillf Danton
2010-12-26 9:08 ` Rakib Mullick
2010-12-26 12:05 ` Hillf Danton
2010-12-26 12:56 ` Rakib Mullick
2010-12-27 14:04 ` Hillf Danton
2010-12-27 20:08 ` Randy Dunlap
2010-12-29 14:57 ` Hillf Danton
2010-12-27 21:15 ` Arnd Bergmann
2010-12-28 13:13 ` Hillf Danton
2010-12-28 15:51 ` Daniel Walker
2010-12-29 11:47 ` Arnd Bergmann [this message]
2010-12-29 14:42 ` Hillf Danton
2010-12-29 14:58 ` Daniel Walker
2010-12-29 15:03 ` Hillf Danton
2010-12-29 19:16 ` Arnd Bergmann
2010-12-30 14:21 ` Hillf Danton
2010-12-30 15:56 ` Arnd Bergmann
2011-01-04 14:03 ` Pavel Machek
2011-01-04 14:18 ` Hillf Danton
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