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Re: NPTL futex error handling

From: Florian Weimer <fweimer at redhat dot com>
To: Siddhesh Poyarekar <siddhesh dot poyarekar at gmail dot com>
Cc: GNU C Library <libc-alpha at sourceware dot org>
Date: Mon, 27 Jan 2014 15:53:22 +0100
Subject: Re: NPTL futex error handling
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References: <52E66CD1 dot 5030402 at redhat dot com> <CAAHN_R2bBH_xLA7dB_4zDXZyLURb6Euvcpni3GWFU2wY1Mvb0Q at mail dot gmail dot com>

On 01/27/2014 03:38 PM, Siddhesh Poyarekar wrote:

On 27 January 2014 19:57, Florian Weimer <fweimer@redhat.com> wrote:

Looking at the kernel code, I believe that FUTEX_LOCK_PI and FUTEX_WAKE (in
the case of cross-process mutexes, it seems) can fail with ENOMEM, in
addition to the more-or-less expected failure cases.

Is the ENOMEM return value due to kernel changes after the initial futex
implementation, or has this already been evaluated and deemed not be
necessary for correctness?


I guess you're referring to the return from refill_pi_state_cache?


Yes, and the call to get_user_pages in the cross-process case.

--
Florian Weimer / Red Hat Product Security Team

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References:
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  - From: Florian Weimer
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