Date: Fri, 9 Jul 2004 17:46:27 +0000 (UTC) From: John Baldwin <jhb@FreeBSD.org> To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/kern subr_witness.c Message-ID: <200407091746.i69HkRJS087027@repoman.freebsd.org>
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jhb 2004-07-09 17:46:27 UTC
FreeBSD src repository
Modified files:
sys/kern subr_witness.c
Log:
Check the lock lists to see if they are empty directly rather than
assigning a pointer to the list and then dereferencing the pointer as a
second step. When the first spin lock is acquired, curthread is not in
a critical section so it may be preempted and would end up using another
CPUs lock list instead of its own.
When this code was in witness_lock() this sequence was safe as curthread
was in a critical section already since witness_lock() is called after the
lock is acquired.
Tested by: Daniel Lang dl at leo.org
Revision Changes Path
1.175 +21 -9 src/sys/kern/subr_witness.c
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