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cpu/esp_common: improve thread safety for locking functions

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Dynamic allocation and initialization of the mutex used by a newlib locking variable must not be interrupted. Since a thread context switch can occur on exit from an ISR, the allocation and initialization of the mutex must be guarded by disabling interrupts. The same must be done for the release of such a locking variable.
This commit is contained in:
Gunar Schorcht 2022-09-01 15:50:26 +02:00
parent 270001a42e
commit 1eb18c2949
1 changed files with 26 additions and 6 deletions
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32
cpu/esp_common/syscalls.c
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@ -80,20 +80,24 @@ static _lock_t *__malloc_static_object = NULL;
void IRAM_ATTR _lock_init(_lock_t *lock)
{
assert(lock != NULL);
assert(lock != NULL); /* lock must not be NULL */
/* prevent a context switch between the allocation and the initialization */
uint32_t state = irq_disable();
mutex_t* mtx = malloc(sizeof(mutex_t));
if (mtx) {
memset(mtx, 0, sizeof(mutex_t));
*lock = (_lock_t)mtx;
}
/* cppcheck-suppress memleak; mtx is stored in lock */
irq_restore(state);
}
void IRAM_ATTR _lock_init_recursive(_lock_t *lock)
{
assert(lock != NULL);
assert(lock != NULL); /* lock must not be NULL */
#ifdef MCU_ESP8266
/* _malloc_rmtx is static and has not to be allocated */
@ -102,35 +106,51 @@ void IRAM_ATTR _lock_init_recursive(_lock_t *lock)
}
#endif
rmutex_t* rmtx = malloc(sizeof(rmutex_t));
/* prevent a context switch between the allocation and the initialization */
uint32_t state = irq_disable();
rmutex_t* rmtx = malloc(sizeof(rmutex_t));
if (rmtx) {
memset(rmtx, 0, sizeof(rmutex_t));
*lock = (_lock_t)rmtx;
}
/* cppcheck-suppress memleak; rmtx is stored in lock */
irq_restore(state);
}
void IRAM_ATTR _lock_close(_lock_t *lock)
{
assert(lock != NULL);
/* locking variable has to be valid and initialized */
assert(lock != NULL && *lock != 0);
#ifdef MCU_ESP8266
assert(lock != __malloc_static_object);
#endif
/* prevent a context switch between freeing and resetting */
uint32_t state = irq_disable();
free((void*)*lock);
*lock = 0;
irq_restore(state);
}
void IRAM_ATTR _lock_close_recursive(_lock_t *lock)
{
assert(lock != NULL);
/* locking variable has to be valid and initialized */
assert(lock != NULL && *lock != 0);
#ifdef MCU_ESP8266
assert(lock != __malloc_static_object);
#endif
/* prevent a context switch between freeing and resetting */
uint32_t state = irq_disable();
free((void*)*lock);
*lock = 0;
irq_restore(state);
}
void IRAM_ATTR _lock_acquire(_lock_t *lock)