[Bug 1091186] Re: Backport upstream bug 13844 - fix for futex issue

[Adam Conrad]

** Changed in: eglibc (Ubuntu Precise)
     Assignee: (unassigned) => Adam Conrad (adconrad)

** Changed in: eglibc (Ubuntu Quantal)
     Assignee: (unassigned) => Adam Conrad (adconrad)

** Changed in: eglibc (Ubuntu)
     Assignee: (unassigned) => Adam Conrad (adconrad)

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https://bugs.launchpad.net/bugs/1091186

Title:
  Backport upstream bug 13844 - fix for futex issue

Status in Embedded GLIBC:
  Fix Released
Status in “eglibc” package in Ubuntu:
  Fix Released
Status in “eglibc” source package in Precise:
  Confirmed
Status in “eglibc” source package in Quantal:
  Confirmed

Bug description:
  [Impact / Justification]
  There was a bug in glibc where custom lowlevellock implementations weren't being used, but rather the generic one was instead.  This was a non-issue on most arches, however hppa, ARM, and Sparc needed their own custom implementation to have sane futexes.  The patch from upstream fixes this by swapping a "" include for a <> include, which correctly walks sysdeps paths and grabs the arch-specific implementations.

  [Test Case]
  I don't personally have a good test for this, but there are several people very keen on having this fix in that will test quite heavily on my behalf, I'm told.  I'll make sure they do so (and bonus points if they document their testcase)...

  [Regression Potential]
  This patch has zero effect on i386, x86_64, and powerpc, and the architecture this does effect (armel/armhf) was quite fundamentally broken, apparently, so the only risk here is that it remains broken, which I'm told by people who've already tested, it won't.

  [Original Report]
  There is a subtle futex bug in glibc 2.15 which is fixed dealt with by BZ #13844 (http://sourceware.org/bugzilla/show_bug.cgi?id=13844).

  This is being hit regularly when testing locks on ARM.

  Can this be backported to precise and quantal (which I believe are
  both 2.15 based)?

  The patch is here:
  http://sourceware.org/git/?p=glibc.git;a=commit;h=7e7fa5f8719c0a497f4b262e6fb5625c13b6c22e

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