From 0875ec4dd55a548a1f8a27674b1c136c0800d73d Mon Sep 17 00:00:00 2001 From: Erik Gabriel Carrillo Date: Wed, 9 Sep 2020 09:41:14 -0500 Subject: [PATCH] timer: add limitation note for sync stop and reset 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@dpdk.org Signed-off-by: Erik Gabriel Carrillo Reviewed-by: Honnappa Nagarahalli --- 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 7af83783b0..22a27aa08d 100644 --- a/lib/librte_timer/rte_timer.h +++ b/lib/librte_timer/rte_timer.h @@ -262,6 +262,12 @@ 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, @@ -301,6 +307,12 @@ 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); -- 2.20.1