davidxu 2006-02-15 23:52:01 UTC
FreeBSD src repository
Modified files:
sys/sys proc.h sleepqueue.h
sys/kern kern_condvar.c kern_kse.c kern_sig.c
kern_synch.c kern_thread.c
subr_sleepqueue.c
Log:
Fix a long standing race between sleep queue and thread
suspension code. When a thread A is going to sleep, it calls
sleepq_catch_signals() to detect any pending signals or thread
suspension request, if nothing happens, it returns without
holding process lock or scheduler lock, this opens a race
window which allows thread B to come in and do process
suspension work, however since A is still at running state,
thread B can do nothing to A, thread A continues, and puts
itself into actually sleeping state, but B has never seen it,
and it sits there forever until B is woken up by other threads
sometimes later(this can be very long delay or never
happen). Fix this bug by forcing sleepq_catch_signals to
return with scheduler lock held.
Fix sleepq_abort() by passing it an interrupted code, previously,
it worked as wakeup_one(), and the interruption can not be
identified correctly by sleep queue code when the sleeping
thread is resumed.
Let thread_suspend_check() returns EINTR or ERESTART, so sleep
queue no longer has to use SIGSTOP as a hack to build a return
value.
Reviewed by: jhb
MFC after: 1 week
Revision Changes Path
1.54 +2 -9 src/sys/kern/kern_condvar.c
1.222 +1 -1 src/sys/kern/kern_kse.c
1.323 +11 -6 src/sys/kern/kern_sig.c
1.276 +2 -8 src/sys/kern/kern_synch.c
1.229 +4 -4 src/sys/kern/kern_thread.c
1.24 +76 -81 src/sys/kern/subr_sleepqueue.c
1.453 +1 -1 src/sys/sys/proc.h
1.7 +2 -4 src/sys/sys/sleepqueue.h
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