antmerlino commented on a change in pull request #1380:
URL: https://github.com/apache/incubator-nuttx/pull/1380#discussion_r452284698
##########
File path: arch/arm/src/stm32f7/stm32_tickless.c
##########
@@ -988,22 +988,31 @@ int up_timer_start(FAR const struct timespec *ts)
}
#endif
+#ifdef CONFIG_SCHED_TICKLESS_ALARM
int up_alarm_start(FAR const struct timespec *ts)
{
uint64_t tm = ((uint64_t)ts->tv_sec * NSEC_PER_SEC + ts->tv_nsec) /
NSEC_PER_TICK;
- uint64_t counter = ((uint64_t)g_tickless.overflow << 32) |
- STM32_TIM_GETCOUNTER(g_tickless.tch);
-
- g_tickless.last_alrm = tm;
+ irqstate_t flags;
- int32_t diff = tm / NSEC_PER_TICK + counter;
+ flags = enter_critical_section();
STM32_TIM_SETCOMPARE(g_tickless.tch, CONFIG_STM32F7_TICKLESS_CHANNEL, tm);
stm32_tickless_ackint(g_tickless.channel);
stm32_tickless_enableint(CONFIG_STM32F7_TICKLESS_CHANNEL);
+ g_tickless.pending = true;
+
+ uint64_t counter = ((uint64_t)g_tickless.overflow << 32) |
+ STM32_TIM_GETCOUNTER(g_tickless.tch);
+
+ if (counter > tm)
+ {
+ stm32_interval_handler();
Review comment:
```
358 /* Start the watchdog */
359
360 wd_start(rtcb->waitdog, waitticks,
361 nxsig_timeout, 1, wdparm.pvarg);
362
363 /* Now wait for either the signal or the watchdog, but
364 * first, make sure this is not the idle task,
365 * descheduling that isn't going to end well.
366 */
367
368 DEBUGASSERT(NULL != rtcb->flink);
369 up_block_task(rtcb, TSTATE_WAIT_SIG);
```
So my changes fix the issue at the tickless driver level, however now there
is another race condition in sig_timedwait.c.
The issue is that nxsig_timeout can occur before we get into up_block_task.
I'm not sure how to protect for this yet.
@patacongo @davids5 @xiaoxiang781216 Any ideas?
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