* Cheap lock for user mode processes release when process exits
@ 2007-04-13 1:54 mchu
2007-04-13 2:43 ` Andrew Morton
0 siblings, 1 reply; 2+ messages in thread
From: mchu @ 2007-04-13 1:54 UTC (permalink / raw)
To: linux-kernel
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
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Cheap lock for user mode processes release when process exits
2007-04-13 1:54 Cheap lock for user mode processes release when process exits mchu
@ 2007-04-13 2:43 ` Andrew Morton
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2007-04-13 2:43 UTC (permalink / raw)
To: mchu; +Cc: linux-kernel
On Fri, 13 Apr 2007 01:54:28 +0000 (GMT) <mchu@mirapoint.com> wrote:
> 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?
>
Robust futexes: http://lwn.net/Articles/172149/
But I don't know whether RH backported them into RHEL4.
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2007-04-13 2:43 ` Andrew Morton
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