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fix(esp_timer): Fix esp_timer task dispatch stall

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The task dispatch method for the esp_timer could stall even if it is
armed if ther ISR dispatch alarm triggers close to the task dispatch.
This MR fixes a bug where the esp_timer cleared the incorrect cached
array timer index and subsequently the timer task is never woken up.

Closes https://github.com/espressif/esp-idf/issues/18808
This commit is contained in:
Sudeep Mohanty
2026-08-27 12:55:06 +03:00
committed by Konstantin Kondrashov
parent d293b6b6c9
commit 0da6fc569a
3 changed files with 46 additions and 43 deletions
Download Patch File Download Diff File Expand all files Collapse all files
components/esp_timer/private_include/esp_timer_impl.h
+12 -3
View File
@@ -142,9 +142,18 @@ void esp_timer_impl_init_system_time(void);
#if CONFIG_ESP_TIMER_SUPPORTS_ISR_DISPATCH_METHOD
/**
* @brief Set the next alarm if there is such an alarm in the cached array.
* @brief Check which alarm slots have fired and disarm them.
*
* @note Available only when CONFIG_ESP_TIMER_SUPPORTS_ISR_DISPATCH_METHOD is enabled.
* For each dispatch method (TASK and ISR), checks if the cached alarm deadline
* has expired. If so, clears the deadline (resets to UINT64_MAX) and sets the
* corresponding bit in the returned mask. After processing both slots,
* reprograms the hardware alarm to the earliest remaining cached deadline.
*
* Must be called only from ISR context.
*
* @return Bitmask of the dispatch methods whose alarm was due:
* bit 0 set means the TASK-dispatch alarm fired,
* bit 1 set means the ISR-dispatch alarm fired.
*/
void esp_timer_impl_try_to_set_next_alarm(void);
uint32_t esp_timer_impl_claim_due_alarms(void);
#endif
components/esp_timer/src/esp_timer.c
+16 -21
View File
@@ -476,13 +476,11 @@ static ESP_TIMER_IRAM_ATTR void timer_list_unlock(esp_timer_dispatch_t timer_typ
}
#ifdef CONFIG_ESP_TIMER_SUPPORTS_ISR_DISPATCH_METHOD
static ESP_TIMER_IRAM_ATTR bool timer_process_alarm(esp_timer_dispatch_t dispatch_method)
#else
static bool timer_process_alarm(esp_timer_dispatch_t dispatch_method)
ESP_TIMER_IRAM_ATTR
#endif
static void timer_process_alarm(esp_timer_dispatch_t dispatch_method)
{
timer_list_lock(dispatch_method);
bool processed = false;
esp_timer_handle_t it;
while (1) {
it = LIST_FIRST(&s_timers[dispatch_method]);
@@ -492,7 +490,6 @@ static bool timer_process_alarm(esp_timer_dispatch_t dispatch_method)
break;
}
ESP_COMPILER_DIAGNOSTIC_POP("-Wanalyzer-use-after-free")
processed = true;
LIST_REMOVE(it, list_entry);
if (it->event_id == EVENT_ID_DELETE_TIMER) {
// It is handled only by ESP_TIMER_TASK (see esp_timer_delete()).
@@ -534,17 +531,9 @@ static bool timer_process_alarm(esp_timer_dispatch_t dispatch_method)
#endif
}
} // while(1)
if (it) {
if (dispatch_method == ESP_TIMER_TASK || (dispatch_method != ESP_TIMER_TASK && processed == true)) {
esp_timer_impl_set_alarm_id(it->alarm, dispatch_method);
}
} else {
if (processed) {
esp_timer_impl_set_alarm_id(UINT64_MAX, dispatch_method);
}
}
uint64_t next_alarm = (it != NULL) ? it->alarm : UINT64_MAX;
esp_timer_impl_set_alarm_id(next_alarm, dispatch_method);
timer_list_unlock(dispatch_method);
return processed;
}
static void timer_task(void* arg)
@@ -562,24 +551,30 @@ ESP_TIMER_IRAM_ATTR void esp_timer_isr_dispatch_need_yield(void)
assert(xPortInIsrContext());
s_isr_dispatch_need_yield = pdTRUE;
}
#endif
static void ESP_TIMER_IRAM_ATTR timer_alarm_handler(void* arg)
{
BaseType_t xHigherPriorityTaskWoken = pdFALSE;
bool isr_timers_processed = false;
#ifdef CONFIG_ESP_TIMER_SUPPORTS_ISR_DISPATCH_METHOD
esp_timer_impl_try_to_set_next_alarm();
// process timers with ISR dispatch method
isr_timers_processed = timer_process_alarm(ESP_TIMER_ISR);
uint32_t due_alarm_mask = esp_timer_impl_claim_due_alarms();
if (due_alarm_mask & (1U << ESP_TIMER_ISR)) {
timer_process_alarm(ESP_TIMER_ISR);
}
xHigherPriorityTaskWoken = s_isr_dispatch_need_yield;
s_isr_dispatch_need_yield = pdFALSE;
#endif
if (isr_timers_processed == false) {
if (due_alarm_mask & (1U << ESP_TIMER_TASK)) {
vTaskNotifyGiveFromISR(s_timer_task, &xHigherPriorityTaskWoken);
}
#else
vTaskNotifyGiveFromISR(s_timer_task, &xHigherPriorityTaskWoken);
#endif
if (xHigherPriorityTaskWoken == pdTRUE) {
portYIELD_FROM_ISR();
}
components/esp_timer/src/esp_timer_impl_common.c
+18 -19
View File
@@ -38,29 +38,28 @@ void ESP_TIMER_IRAM_ATTR esp_timer_impl_set_alarm(uint64_t timestamp)
}
#ifdef CONFIG_ESP_TIMER_SUPPORTS_ISR_DISPATCH_METHOD
void ESP_TIMER_IRAM_ATTR esp_timer_impl_try_to_set_next_alarm(void)
/* Reprogram the hardware alarm to the nearest pending deadline,
* i.e. MIN(timestamp_id[0], timestamp_id[1]). The timestamp_id[] cache is not modified.
* Must be called with s_time_update_lock held. */
static inline void ESP_TIMER_IRAM_ATTR esp_timer_impl_rearm_alarm(void)
{
esp_timer_impl_set_alarm_id(timestamp_id[ESP_TIMER_TASK], ESP_TIMER_TASK);
}
uint32_t ESP_TIMER_IRAM_ATTR esp_timer_impl_claim_due_alarms(void)
{
portENTER_CRITICAL_ISR(&s_time_update_lock);
unsigned now_alarm_idx; // ISR is called due to this current alarm
unsigned next_alarm_idx; // The following alarm after now_alarm_idx
if (timestamp_id[0] < timestamp_id[1]) {
now_alarm_idx = 0;
next_alarm_idx = 1;
} else {
now_alarm_idx = 1;
next_alarm_idx = 0;
}
if (timestamp_id[next_alarm_idx] != UINT64_MAX) {
// The following alarm is valid and can be used.
// Remove the current alarm from consideration.
esp_timer_impl_set_alarm_id(UINT64_MAX, now_alarm_idx);
} else {
// There is no the following alarm.
// Remove the current alarm from consideration as well.
timestamp_id[now_alarm_idx] = UINT64_MAX;
uint64_t now = esp_timer_impl_get_time();
uint32_t due_mask = 0;
for (unsigned alarm_id = 0; alarm_id < sizeof(timestamp_id) / sizeof(timestamp_id[0]); ++alarm_id) {
if (timestamp_id[alarm_id] <= now) {
due_mask |= 1U << alarm_id;
timestamp_id[alarm_id] = UINT64_MAX;
}
}
esp_timer_impl_rearm_alarm();
portEXIT_CRITICAL_ISR(&s_time_update_lock);
return due_mask;
}
#endif