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From: "Justin T. Gibbs" <gibbs@FreeBSD.org>
Date: Mon, 13 Jun 2011 21:21:02 +0000 (UTC)
To: cvs-src-old@freebsd.org
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Subject: cvs commit: src/sys/kern subr_devstat.c
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gibbs       2011-06-13 21:21:02 UTC

  FreeBSD src repository

  Modified files:
    sys/kern             subr_devstat.c 
  Log:
  SVN rev 223061 on 2011-06-13 21:21:02Z by gibbs
  
  Fix a couple of race conditions in devstat(9) initialization.
  
  In devstat_new_entry(), there is no need to initialize the queue
  and the mutex in this function.  There are ways to do static
  initialization on both, so use STAILQ_HEAD_INITIALIZER and
  MTX_SYSINIT to initialize the queue and the mutex.
  
  In devstat_alloc(), use an atomic test and set routine to guard
  making our entry in /dev.  Using just a plain static variable
  creates a race condition on multiprocessor machines.  If you
  attempt to create a second entry in devfs, the kernel will panic.
  
  Submitted by:   kdm
  Reviewed by:    gibbs
  Sponsored by:   Spectra Logic Corporation
  MFC after:      1 week.
  
  Revision  Changes    Path
  1.57      +3 -9      src/sys/kern/subr_devstat.c