From: Pawel Wodkowski Date: Wed, 1 Oct 2014 14:20:22 +0000 (+0100) Subject: alarm: make cancellation thread-safe X-Git-Tag: spdx-start~10138 X-Git-Url: http://git.droids-corp.org/?a=commitdiff_plain;h=a1a57f3e11cddf6d8f46483fa82b80d20aa6e1d9;p=dpdk.git alarm: make cancellation thread-safe It eliminates a race between threads using rte_alarm_cancel() and rte_alarm_set(). Signed-off-by: Pawel Wodkowski Acked-by: Konstantin Ananyev Acked-by: Neil Horman --- diff --git a/lib/librte_eal/common/include/rte_alarm.h b/lib/librte_eal/common/include/rte_alarm.h index d451522044..4012cd67ef 100644 --- a/lib/librte_eal/common/include/rte_alarm.h +++ b/lib/librte_eal/common/include/rte_alarm.h @@ -76,7 +76,8 @@ typedef void (*rte_eal_alarm_callback)(void *arg); int rte_eal_alarm_set(uint64_t us, rte_eal_alarm_callback cb, void *cb_arg); /** - * Function to cancel an alarm callback which has been registered before. + * Function to cancel an alarm callback which has been registered before. If + * used outside alarm callback it wait for all callbacks to finish execution. * * @param cb_fn * alarm callback @@ -86,7 +87,14 @@ int rte_eal_alarm_set(uint64_t us, rte_eal_alarm_callback cb, void *cb_arg); * can be used here. * * @return - * - The number of callbacks removed + * - value greater than 0 and rte_errno not changed - returned value is + * the number of canceled alarm callback functions + * - value greater or equal 0 and rte_errno set to EINPROGRESS, at least one + * alarm could not be canceled because cancellation was requested from alarm + * callback context. Returned value is the number of succesfuly canceled + * alarm callbacks + * - 0 and rte_errno set to ENOENT - no alarm found + * - -1 and rte_errno set to EINVAL - invalid parameter (NULL callback) */ int rte_eal_alarm_cancel(rte_eal_alarm_callback cb_fn, void *cb_arg); diff --git a/lib/librte_eal/linuxapp/eal/eal_alarm.c b/lib/librte_eal/linuxapp/eal/eal_alarm.c index 480f0cb6a6..e8da32fc5e 100644 --- a/lib/librte_eal/linuxapp/eal/eal_alarm.c +++ b/lib/librte_eal/linuxapp/eal/eal_alarm.c @@ -69,7 +69,8 @@ struct alarm_entry { struct timeval time; rte_eal_alarm_callback cb_fn; void *cb_arg; - volatile int executing; + volatile uint8_t executing; + volatile pthread_t executing_id; }; static LIST_HEAD(alarm_list, alarm_entry) alarm_list = LIST_HEAD_INITIALIZER(); @@ -108,11 +109,13 @@ eal_alarm_callback(struct rte_intr_handle *hdl __rte_unused, (ap->time.tv_sec < now.tv_sec || (ap->time.tv_sec == now.tv_sec && ap->time.tv_usec <= now.tv_usec))){ ap->executing = 1; + ap->executing_id = pthread_self(); rte_spinlock_unlock(&alarm_list_lk); ap->cb_fn(ap->cb_arg); rte_spinlock_lock(&alarm_list_lk); + LIST_REMOVE(ap, next); rte_free(ap); } @@ -145,7 +148,7 @@ rte_eal_alarm_set(uint64_t us, rte_eal_alarm_callback cb_fn, void *cb_arg) if (us < 1 || us > (UINT64_MAX - US_PER_S) || cb_fn == NULL) return -EINVAL; - new_alarm = rte_malloc(NULL, sizeof(*new_alarm), 0); + new_alarm = rte_zmalloc(NULL, sizeof(*new_alarm), 0); if (new_alarm == NULL) return -ENOMEM; @@ -156,7 +159,6 @@ rte_eal_alarm_set(uint64_t us, rte_eal_alarm_callback cb_fn, void *cb_arg) new_alarm->cb_arg = cb_arg; new_alarm->time.tv_usec = (now.tv_usec + us) % US_PER_S; new_alarm->time.tv_sec = now.tv_sec + ((now.tv_usec + us) / US_PER_S); - new_alarm->executing = 0; rte_spinlock_lock(&alarm_list_lk); if (!handler_registered) { @@ -202,34 +204,65 @@ rte_eal_alarm_cancel(rte_eal_alarm_callback cb_fn, void *cb_arg) { struct alarm_entry *ap, *ap_prev; int count = 0; + int err = 0; + int executing; - if (!cb_fn) + if (!cb_fn) { + rte_errno = EINVAL; return -1; - - rte_spinlock_lock(&alarm_list_lk); - /* remove any matches at the start of the list */ - while ((ap = LIST_FIRST(&alarm_list)) != NULL && - cb_fn == ap->cb_fn && ap->executing == 0 && - (cb_arg == (void *)-1 || cb_arg == ap->cb_arg)) { - LIST_REMOVE(ap, next); - rte_free(ap); - count++; } - ap_prev = ap; - /* now go through list, removing entries not at start */ - LIST_FOREACH(ap, &alarm_list, next) { - /* this won't be true first time through */ - if (cb_fn == ap->cb_fn && ap->executing == 0 && + do { + executing = 0; + rte_spinlock_lock(&alarm_list_lk); + /* remove any matches at the start of the list */ + while ((ap = LIST_FIRST(&alarm_list)) != NULL && + cb_fn == ap->cb_fn && (cb_arg == (void *)-1 || cb_arg == ap->cb_arg)) { - LIST_REMOVE(ap,next); - rte_free(ap); - count++; - ap = ap_prev; + + if (ap->executing == 0) { + LIST_REMOVE(ap, next); + rte_free(ap); + count++; + } else { + /* If calling from other context, mark that alarm is executing + * so loop can spin till it finish. Otherwise we are trying to + * cancel our self - mark it by EINPROGRESS */ + if (pthread_equal(ap->executing_id, pthread_self()) == 0) + executing++; + else + err = EINPROGRESS; + + break; + } } ap_prev = ap; - } - rte_spinlock_unlock(&alarm_list_lk); + + /* now go through list, removing entries not at start */ + LIST_FOREACH(ap, &alarm_list, next) { + /* this won't be true first time through */ + if (cb_fn == ap->cb_fn && + (cb_arg == (void *)-1 || cb_arg == ap->cb_arg)) { + + if (ap->executing == 0) { + LIST_REMOVE(ap, next); + rte_free(ap); + count++; + ap = ap_prev; + } else if (pthread_equal(ap->executing_id, pthread_self()) == 0) + executing++; + else + err = EINPROGRESS; + } + ap_prev = ap; + } + rte_spinlock_unlock(&alarm_list_lk); + } while (executing != 0); + + if (count == 0 && err == 0) + rte_errno = ENOENT; + else if (err) + rte_errno = err; + return count; } -