[dpdk-stable] [PATCH 1/1] timer: add limitation note for sync stop and reset
Erik Gabriel Carrillo
erik.g.carrillo at intel.com
Wed Sep 9 16:38:50 CEST 2020
If a timer's callback function calls rte_timer_reset_sync() or
rte_timer_stop_sync() on another timer that is in the RUNNING state and
owned by the current lcore, the *_sync() calls will loop indefinitely.
Relatedly, if a timer's callback function calls *_sync() on another
timer that is in the RUNNING state and is owned by a different lcore,
but a timer callback function runs on that different lcore and calls
*_sync() on a timer that is in the RUNNING state and owned by the
current lcore, the two lcores will loop indefinitely.
Add a note in the rte_timer_stop_sync and rte_timer_reset_sync
documentation that indicates that these APIs should not be used inside
timer callback functions in order to avoid the hangs described above,
and suggests an alternative.
Bugzilla ID: 491
Cc: stable at dpdk.org
Signed-off-by: Erik Gabriel Carrillo <erik.g.carrillo at intel.com>
---
lib/librte_timer/rte_timer.h | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/lib/librte_timer/rte_timer.h b/lib/librte_timer/rte_timer.h
index c6b3d45..d7c3e03 100644
--- a/lib/librte_timer/rte_timer.h
+++ b/lib/librte_timer/rte_timer.h
@@ -274,6 +274,12 @@ int rte_timer_reset(struct rte_timer *tim, uint64_t ticks,
* The callback function of the timer.
* @param arg
* The user argument of the callback function.
+ *
+ * @note
+ * This API should not be called inside a timer's callback function to
+ * reset another timer; doing so could hang in certain scenarios. Instead,
+ * the rte_timer_reset() API can be called directly and its return code
+ * can be checked for success or failure.
*/
void
rte_timer_reset_sync(struct rte_timer *tim, uint64_t ticks,
@@ -313,6 +319,12 @@ int rte_timer_stop(struct rte_timer *tim);
*
* @param tim
* The timer handle.
+ *
+ * @note
+ * This API should not be called inside a timer's callback function to
+ * stop another timer; doing so could hang in certain scenarios. Instead, the
+ * rte_timer_stop() API can be called directly and its return code can
+ * be checked for success or failure.
*/
void rte_timer_stop_sync(struct rte_timer *tim);
--
2.6.4
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