linux-kernel - Cheap lock for user mode processes release when process exits

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Message-Id: <20070413015428.AMJ80009@dougfood.mirapoint.com>
Date:	Fri, 13 Apr 2007 01:54:28 +0000 (GMT)
From:	<mchu@...apoint.com>
To:	<linux-kernel@...r.kernel.org>
Subject: Cheap lock for user mode processes release
 when process exits

Hi all,

Maybe someone here knows better.

I have several user-mode processes using shared mmap.  There can be several reader processes and only one writer.  Readers access the shared region frequently, writer seldom.

Naturally, multi-reader/single-writer locks works best.  I tried this with futex on 2.6.9-42.EL.  However, if one of the processes is killed/exits, the lock doesn't get released.

I can trap the signal to release the lock, but not all signals like kill.

Anyway I can achieve this without a potential deadlock?

Thanks,
Michael
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