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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; } esp_pthread_mutex_t;
static SemaphoreHandle_t s_once_mux = NULL;
static SemaphoreHandle_t s_threads_mux = NULL; static SemaphoreHandle_t s_threads_mux = NULL;
static portMUX_TYPE s_mutex_init_lock = portMUX_INITIALIZER_UNLOCKED; 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) esp_err_t esp_pthread_init(void)
{ {
vListInitialise((List_t *)&s_threads_list); vListInitialise((List_t *)&s_threads_list);
s_once_mux = xSemaphoreCreateRecursiveMutex();
if (s_once_mux == NULL) {
return ESP_ERR_NO_MEM;
}
s_threads_mux = xSemaphoreCreateMutex(); s_threads_mux = xSemaphoreCreateMutex();
if (s_threads_mux == NULL) { if (s_threads_mux == NULL) {
vSemaphoreDelete(s_once_mux);
return ESP_ERR_NO_MEM; return ESP_ERR_NO_MEM;
} }
return ESP_OK; return ESP_OK;
@ -346,30 +340,18 @@ int pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
return EINVAL; return EINVAL;
} }
TaskHandle_t cur_task = xTaskGetCurrentTaskHandle(); // Check if once_control belongs to internal DRAM for uxPortCompare to succeed
uint8_t do_execute = 0; if (!esp_ptr_internal(once_control)) {
// do not take mutex if OS is not running yet ESP_LOGE(TAG, "%s: once_control should belong to internal DRAM region!", __FUNCTION__);
if (xTaskGetSchedulerState() == taskSCHEDULER_NOT_STARTED || return EINVAL;
// 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();
}
} }
else
{ uint32_t res = 1;
ESP_LOGE(TAG, "%s: Failed to lock!", __FUNCTION__); uxPortCompareSet((uint32_t *) &once_control->init_executed, 0, &res);
return EBUSY; // 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; return 0;