OpenAFS Master Repository branch, master, updated. openafs-devel-1_5_76-2112-g22cba8e

[Gerrit Code Review]

The following commit has been merged in the master branch:
commit 22cba8e9702f3673c335bf834a9ee2c5e5fd9b6e
Author: Jeffrey Altman <jaltman@your-file-system.com>
Date:   Thu Jan 19 15:25:44 2012 -0500

    Windows: cm_buf refcnt must hold buf_globalLock
    
    An assertion in buf_Recycle() was being triggered when a cm_buf_t
    object was supposed to be in the free buffer list but wasn't.
    buf_Recycle() was racing with another thread.  The test for
    refCount == 0 was performed while holding the buf_globalLock
    exclusively but the InterlockedDecrement(refCount) in buf_Release()
    was performed without holding buf_globalLock at all.  buf_globalLOck
    must be held at least as a read lock.  Otherwise, the refCount can
    reach 0 prior to the thread blocking for exclusive access to the
    buf_globalLock.  This provides buf_Recycle() which is holding
    buf_globalLock the opportunity to race.
    
    The solution is to make sure that buf_Release() always holds
    buf_globalLock as a read lock and then use buf_ReleaseLocked()
    to perform the actual decrement and test.
    
    Change-Id: Ieb67548a7e44fa5f06f9346f428b1edadfc80696
    Reviewed-on: http://gerrit.openafs.org/6576
    Tested-by: BuildBot <buildbot@rampaginggeek.com>
    Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
    Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>

 src/WINNT/afsd/cm_buf.c |   31 +++----------------------------
 1 files changed, 3 insertions(+), 28 deletions(-)

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