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sema: fix race-condition that causes timeout reset

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This commit is contained in:
Martine Lenders 2015-11-11 11:30:12 +01:00
parent aca1224401
commit 77547dd399
1 changed files with 14 additions and 11 deletions
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25
sys/sema/sema.c
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@ -65,16 +65,26 @@ int sema_destroy(sema_t *sema)
int sema_wait_timed_msg(sema_t *sema, uint64_t timeout, msg_t *msg) int sema_wait_timed_msg(sema_t *sema, uint64_t timeout, msg_t *msg)
{ {
unsigned old_state;
msg_t timeout_msg;
xtimer_t timeout_timer;
if (sema == NULL) { if (sema == NULL) {
return -EINVAL; return -EINVAL;
} }
if (timeout != 0) {
old_state = disableIRQ();
timeout_msg.type = MSG_TIMEOUT;
timeout_msg.content.ptr = (char *)sema;
/* we will stay in the same stack context so we can use timeout_msg */
xtimer_set_msg64(&timeout_timer, timeout, &timeout_msg, sched_active_pid);
restoreIRQ(old_state);
}
while (1) { while (1) {
unsigned old_state = disableIRQ();
priority_queue_node_t n; priority_queue_node_t n;
xtimer_t timeout_timer; unsigned value;
msg_t timeout_msg;
unsigned value = sema->value; old_state = disableIRQ();
value = sema->value;
if (value != 0) { if (value != 0) {
sema->value = value - 1; sema->value = value - 1;
restoreIRQ(old_state); restoreIRQ(old_state);
@ -90,13 +100,6 @@ int sema_wait_timed_msg(sema_t *sema, uint64_t timeout, msg_t *msg)
DEBUG("sema_wait: %" PRIkernel_pid ": Adding node to semaphore queue: prio: %" PRIu32 "\n", DEBUG("sema_wait: %" PRIkernel_pid ": Adding node to semaphore queue: prio: %" PRIu32 "\n",
sched_active_thread->pid, sched_active_thread->priority); sched_active_thread->pid, sched_active_thread->priority);
if (timeout != 0) {
timeout_msg.type = MSG_TIMEOUT;
timeout_msg.content.ptr = (char *)sema;
/* we will stay in the same stack context so we can use timeout_msg */
xtimer_set_msg64(&timeout_timer, timeout, &timeout_msg, sched_active_pid);
}
restoreIRQ(old_state); restoreIRQ(old_state);
msg_receive(msg); msg_receive(msg);