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pthread: Fix pthread_once to use atomic compare and set

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Earlier recursive mutex was being used for this but since
SCOMPARE1 is already being saved/restored during context
switch, atomic compare and set can be used for this.

Signed-off-by: Mahavir Jain <mahavir@espressif.com>
This commit is contained in:
Mahavir Jain 2017-11-03 14:49:04 +05:30
parent 1613044aef
commit 158ecdcfd5
1 changed files with 11 additions and 29 deletions
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40
components/pthread/pthread.c
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@ -62,7 +62,6 @@ typedef struct {
} esp_pthread_mutex_t;
static SemaphoreHandle_t s_once_mux = NULL;
static SemaphoreHandle_t s_threads_mux = NULL;
static portMUX_TYPE s_mutex_init_lock = portMUX_INITIALIZER_UNLOCKED;
@ -74,13 +73,8 @@ static int IRAM_ATTR pthread_mutex_lock_internal(esp_pthread_mutex_t *mux, TickT
esp_err_t esp_pthread_init(void)
{
vListInitialise((List_t *)&s_threads_list);
s_once_mux = xSemaphoreCreateRecursiveMutex();
if (s_once_mux == NULL) {
return ESP_ERR_NO_MEM;
}
s_threads_mux = xSemaphoreCreateMutex();
if (s_threads_mux == NULL) {
vSemaphoreDelete(s_once_mux);
return ESP_ERR_NO_MEM;
}
return ESP_OK;
@ -346,30 +340,18 @@ int pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
return EINVAL;
}
TaskHandle_t cur_task = xTaskGetCurrentTaskHandle();
uint8_t do_execute = 0;
// do not take mutex if OS is not running yet
if (xTaskGetSchedulerState() == taskSCHEDULER_NOT_STARTED ||
// init_routine can call pthread_once for another objects, so use recursive mutex
// FIXME: behaviour is undefined if init_routine calls pthread_once for the same object in the current context
!cur_task || xSemaphoreTakeRecursive(s_once_mux, portMAX_DELAY) == pdTRUE)
{
if (!once_control->init_executed) {
do_execute = 1;
once_control->init_executed = 1;
}
if (cur_task) {
xSemaphoreGiveRecursive(s_once_mux);
}
if (do_execute) {
ESP_LOGV(TAG, "%s: call init_routine %p", __FUNCTION__, once_control);
init_routine();
}
// Check if once_control belongs to internal DRAM for uxPortCompare to succeed
if (!esp_ptr_internal(once_control)) {
ESP_LOGE(TAG, "%s: once_control should belong to internal DRAM region!", __FUNCTION__);
return EINVAL;
}
else
{
ESP_LOGE(TAG, "%s: Failed to lock!", __FUNCTION__);
return EBUSY;
uint32_t res = 1;
uxPortCompareSet((uint32_t *) &once_control->init_executed, 0, &res);
// Check if compare and set was successful
if (res == 0) {
ESP_LOGV(TAG, "%s: call init_routine %p", __FUNCTION__, once_control);
init_routine();
}
return 0;