git: kernel - Close small race in kqueue

[Matthew Dillon]

commit 8e8e1c56e4ab8226e7fcc3ee738f7f9b023f85ea
Author: Matthew Dillon <dillon at apollo.backplane.com>
Date:   Thu Sep 23 17:24:53 2010 -0700

    kernel - Close small race in kqueue
    
    * Normalize the kn_status reprocessing code to close a race.
      A knote_detach_and_drop() during a descriptor close can set
      KN_DELETING and return, leaving a knote undergoing processing
      by another thread marked deleted.
    
      If the other thread is trying to execute a filter the filter can
      wind up being run after the file pointer has been detached
      from the knote, resulting in a panic.
    
    * All KN_DELETING and KN_WAITING flags also now set KN_REPROCESS and
      all KN_REPROCESS handling is dealt with the same way.  The filter
      is run if KN_REPROCESS is not set and if it is set any KN_DELETING
      and KN_WAITING flags are dealt with before the filter is run.

Summary of changes:
 sys/kern/kern_event.c |   56 ++++++++++++++++++++++++++++++------------------
 1 files changed, 35 insertions(+), 21 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/8e8e1c56e4ab8226e7fcc3ee738f7f9b023f85ea


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