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timers: Properly fix timer lockup issue 

Adding timers from within timer callback functions could cause lockups
and memory leaks.
This commit is contained in:
Kim Woelders 2022-10-30 10:01:42 +01:00
parent 286a815b92
commit 6a0c30e77f
1 changed files with 35 additions and 8 deletions
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43
src/timers.c
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@ -25,6 +25,13 @@
#include "list.h"
#include "timers.h"
#define DEBUG_TIMERS 0
#if DEBUG_TIMERS
#define Dprintf(fmt...) if(EDebug(EDBUG_TYPE_TIMERS))Eprintf(fmt)
#else
#define Dprintf(fmt...)
#endif
struct _timer {
unsigned int in_time;
unsigned int at_time;
@ -109,14 +116,19 @@ TimerAdd(int dt_ms, int (*func)(void *data), void *data)
void
TimersRun(unsigned int t_ms)
{
Timer *timer, *q_old, *q_run;
Timer *timer, *q_old, *q_new, *q_run;
timer = q_first;
if (!timer)
return; /* No timers pending */
q_run = q_old = timer;
for (; timer; timer = q_first)
Dprintf("%s - A\n", __func__);
q_new = timer; /* q_new is now temporarily the timer queue */
q_old = timer; /* q_old is the old timer queue */
q_first = NULL; /* q_first holds timers added during timer processing */
q_run = NULL; /* q_run holds the last run timer */
for (; timer; timer = q_new)
{
if (tdiff(timer->at_time, t_ms) > 0)
break;
@ -125,23 +137,25 @@ TimersRun(unsigned int t_ms)
Eprintf("%s - run %p: func=%p data=%p: %8d\n", __func__, timer,
timer->func, timer->data, timer->at_time - t_ms);
q_first = timer->next;
q_new = timer->next;
/* Run this callback */
timer->again = timer->func(timer->data);
q_run = timer;
}
if (q_old != q_first)
if (q_run)
{
/* At least one timer has run */
q_run->next = NULL; /* Terminate expired timer list */
/* Re-schedule/remove timers that have run */
for (timer = q_old; timer; timer = q_old)
q_run = q_new; /* Swap q_first and q_new ... */
q_new = q_first; /* q_new are the new added timers */
q_first = q_run; /* q_first is now the timer queue */
for (timer = q_old; timer; timer = q_run)
{
q_old = timer->next;
timer->next = NULL;
q_run = timer->next;
if (timer->again)
{
timer->at_time += timer->in_time;
@ -152,6 +166,17 @@ TimersRun(unsigned int t_ms)
_TimerDel(timer);
}
}
/* Schedule timers that have been added */
for (timer = q_new; timer; timer = q_run)
{
q_run = timer->next;
_TimerSet(timer); /* Add to timer queue */
}
}
else
{
q_first = q_old; /* Restore timer queue */
}
if (EDebug(EDBUG_TYPE_TIMERS) > 1)
@ -161,6 +186,8 @@ TimersRun(unsigned int t_ms)
timer, timer->func, timer->data, timer->at_time - t_ms,
timer->in_time);
}
Dprintf("%s - B\n", __func__);
}
int