From: Arnd Bergmann <arnd@arndb.de>
To: Darren Hart <dvhltc@us.ibm.com>
Subject: Re: [PATCH] RFC: futex: make futex_lock_pi interruptible
Date: Thu, 29 Oct 2009 09:39:32 +0100
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       Thomas Gleixner <tglx@linutronix.de>,
       Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@elte.hu>,
       Eric Dumazet <eric.dumazet@gmail.com>,
       Dinakar Guniguntala <dino@in.ibm.com>,
       "Stultz, John" <johnstul@us.ibm.com>
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On Tuesday 27 October 2009, Darren Hart wrote:
> The following C test case demonstrates how this patch could be used to
> implement interruptible locking. There is an awful lot of debug code and
> some other relics of a hacked together test in there now, but if anyone
> wanted to test the futex changes, this will do the trick.
> 

Your test program uses a signal handler to interrupt the mutex. If you
are using a signal handler already to implement a user space mutex_cancel,
why can't you just do a longjmp out of the signal handler rather than
modifying the kernel?

	Arnd <><
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