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From: Pawel Jakub Dawidek <pjd@FreeBSD.org>
Date: Tue, 2 Oct 2007 14:48:48 +0000 (UTC)
To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org
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Cc: 
Subject: cvs commit: src/sys/kern kern_sx.c
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pjd         2007-10-02 14:48:48 UTC

  FreeBSD src repository

  Modified files:
    sys/kern             kern_sx.c 
  Log:
  Fix sx_try_slock(), so it only fails when there is an exclusive owner.
  Before that fix, it was possible for the function to fail if number
  of sharers changes between 'x = sx->sx_lock' step and atomic_cmpset_acq_ptr()
  call.
  
  This fixes ZFS problem when ZFS returns strange EIO errors under load.
  In ZFS there is a code that depends on the fact that sx_try_slock() can
  only fail if there is an exclusive owner.
  
  Discussed with: attilio
  Reviewed by:    jhb
  Approved by:    re (kensmith)
  
  Revision  Changes    Path
  1.55      +12 -9     src/sys/kern/kern_sx.c