jhb 2007-08-31 19:01:30 UTC
FreeBSD src repository
Modified files:
sys/kern kern_timeout.c
Log:
Close a race that snuck in with the recent changes to fix a LOR between
the callout_lock spin lock and the sleepqueue spin locks. In the fix,
callout_drain() has to drop the callout_lock so it can acquire the
sleepqueue lock. The state of the callout can change while the
callout_lock is held however (for example, it can be rescheduled via
callout_reset()). The previous code assumed that the only state change
that could happen is that the callout could finish executing. This change
alters callout_drain() to effectively restart and recheck everything
after it acquires the sleepqueue lock thus handling all the possible
states that the callout could be in after any changes while callout_lock
was dropped.
Approved by: re (kensmith)
Tested by: kris
Revision Changes Path
1.105 +27 -13 src/sys/kern/kern_timeout.c
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