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From: Mike Makonnen <mtm@FreeBSD.org>
Date: Sun, 25 May 2003 01:48:11 -0700 (PDT)
To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org,
	cvs-all@FreeBSD.org
X-FreeBSD-CVS-Branch: HEAD
Subject: cvs commit: src/lib/libthr/thread thr_cancel.c thr_private.h
 thr_spinlock.c
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mtm         2003/05/25 01:48:11 PDT

  FreeBSD src repository

  Modified files:
    lib/libthr/thread    thr_cancel.c thr_private.h thr_spinlock.c 
  Log:
  _pthread_cancel() breaks the normal lock order of first locking the
  joined and then the joiner thread. There isn't an easy (sane?) way
  to make it use the correct order without introducing races involving
  the target thread and finding which (active or dead) list it is on. So,
  after locking the canceled thread it will try to lock the joined thread
  and if it fails release the first lock and try again from the top.
  
  Introduce a new function, _spintrylock, which is simply a wrapper arround
  umtx_trylock(), to help accomplish this.
  
  Approved by: re/blanket libthr
  
  Revision  Changes    Path
  1.5       +17 -4     src/lib/libthr/thread/thr_cancel.c
  1.12      +1 -0      src/lib/libthr/thread/thr_private.h
  1.4       +10 -0     src/lib/libthr/thread/thr_spinlock.c