Messages in this thread | | | Date | Sun, 13 Mar 2005 16:13:05 +0300 | From | Oleg Nesterov <> | Subject | Re: [patch] del_timer_sync scalability patch |
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I suspect that del_timer_sync() in its current form is racy.
CPU 0 CPU 1
__run_timers() sets timer->base = NULL
del_timer_sync() starts, calls del_timer(), it returns because timer->base == NULL.
waits until the run is complete: while (base->running_timer == timer) preempt_check_resched(); calls schedule(), or long interrupt happens.
timer reschedules itself, __run_timers() exits.
base->running_timer == NULL, end of loop.
next timer interrupt, __run_timers() picks this timer again, sets timer->base = NULL
if (timer_pending(timer)) // no, timer->base == NULL goto del_again; // not taken
del_timer_sync() returns
timer runs.
No?
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