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Fix a logic error that occur when using the timerfd interface

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This sequence of events posed a problem

timerfd_timer_open
timerfd_timer_enable_continuous
timerfd_timer_set_rate
timerfd_timer_disable_continuous

The reason was that the timing module was written under the assumption
that timerfd_timer_set_rate would not be called between enabling and
disabling continuous mode. What happened in this situation was that 
timerfd_timer_enable_continuous saved off our previously set timer (in this
situation a 0 timer, meaning it never runs out). Then timerfd_timer_disable_continuous
would restore this 0 timer, even though it logically should set the timer to be whatever
was set in timerfd_timer_set_rate.

Now the behavior in timerfd_timer_set_rate is to overwrite the saved timer that may
or may not have been set in timerfd_timer_enable_continuous. Even if
timerfd_timer_enable_continuous has not been previously called, this will not harm the
operation.

Thanks to Terry Wilson for discovering the problem and giving me a really great debug
capture that pointed out the problem clearly



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@168898 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Mark Michelson
2009-01-16 19:54:39 +00:00
parent 3728c3aa92
commit e2f49af37f
1 changed files with 14 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
res/res_timing_timerfd.c
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@@ -131,13 +131,21 @@ static void timerfd_timer_close(int handle)
static int timerfd_timer_set_rate(int handle, unsigned int rate) static int timerfd_timer_set_rate(int handle, unsigned int rate)
{ {
struct itimerspec itspec; struct timerfd_timer *our_timer, find_helper = {
itspec.it_value.tv_sec = 0; .handle = handle,
itspec.it_value.tv_nsec = rate ? (long) (1000000000 / rate) : 0L; };
itspec.it_interval.tv_sec = itspec.it_value.tv_sec;
itspec.it_interval.tv_nsec = itspec.it_value.tv_nsec;
return timerfd_settime(handle, 0, &itspec, NULL); if (!(our_timer = ao2_find(timerfd_timers, &find_helper, OBJ_POINTER))) {
ast_log(LOG_ERROR, "Couldn't find timer with handle %d\n", handle);
return -1;
}
our_timer->saved_timer.it_value.tv_sec = 0;
our_timer->saved_timer.it_value.tv_nsec = rate ? (long) (1000000000 / rate) : 0L;
our_timer->saved_timer.it_interval.tv_sec = our_timer->saved_timer.it_value.tv_sec;
our_timer->saved_timer.it_interval.tv_nsec = our_timer->saved_timer.it_value.tv_nsec;
return timerfd_settime(handle, 0, &our_timer->saved_timer, NULL);
} }
static void timerfd_timer_ack(int handle, unsigned int quantity) static void timerfd_timer_ack(int handle, unsigned int quantity)