[dpdk-dev,3/3] timer: fix race condition in rte_timer_manage()
Commit Message
From: Robert Sanford <rsanford@akamai.com>
Signed-off-by: Robert Sanford <rsanford@akamai.com>
---
lib/librte_timer/rte_timer.c | 45 +++++++++++++++++++++++++++--------------
1 files changed, 29 insertions(+), 16 deletions(-)
@@ -504,6 +504,7 @@ void rte_timer_manage(void)
{
union rte_timer_status status;
struct rte_timer *tim, *next_tim;
+ struct rte_timer *run_first_tim, **pprev;
unsigned lcore_id = rte_lcore_id();
struct rte_timer *prev[MAX_SKIPLIST_DEPTH + 1];
uint64_t cur_time;
@@ -531,8 +532,10 @@ void rte_timer_manage(void)
/* if nothing to do just unlock and return */
if (priv_timer[lcore_id].pending_head.sl_next[0] == NULL ||
- priv_timer[lcore_id].pending_head.sl_next[0]->expire > cur_time)
- goto done;
+ priv_timer[lcore_id].pending_head.sl_next[0]->expire > cur_time) {
+ rte_spinlock_unlock(&priv_timer[lcore_id].list_lock);
+ return;
+ }
/* save start of list of expired timers */
tim = priv_timer[lcore_id].pending_head.sl_next[0];
@@ -546,24 +549,40 @@ void rte_timer_manage(void)
prev[i] ->sl_next[i] = NULL;
}
- /* now scan expired list and call callbacks */
+ /* transition run-list from PENDING to RUNNING */
+ run_first_tim = tim;
+ pprev = &run_first_tim;
+
for ( ; tim != NULL; tim = next_tim) {
next_tim = tim->sl_next[0];
ret = timer_set_running_state(tim);
+ if (likely(ret == 0)) {
+ pprev = &tim->sl_next[0];
+ } else {
+ /* another core is trying to re-config this one,
+ * remove it from local expired list and put it
+ * back on the priv_timer[] skip list */
+ *pprev = next_tim;
+ timer_add(tim, lcore_id, 1);
+ }
+ }
- /* this timer was not pending, continue */
- if (ret < 0)
- continue;
+ /* update the next to expire timer value */
+ priv_timer[lcore_id].pending_head.expire =
+ (priv_timer[lcore_id].pending_head.sl_next[0] == NULL) ? 0 :
+ priv_timer[lcore_id].pending_head.sl_next[0]->expire;
- rte_spinlock_unlock(&priv_timer[lcore_id].list_lock);
+ rte_spinlock_unlock(&priv_timer[lcore_id].list_lock);
+ /* now scan expired list and call callbacks */
+ for (tim = run_first_tim; tim != NULL; tim = next_tim) {
+ next_tim = tim->sl_next[0];
priv_timer[lcore_id].updated = 0;
/* execute callback function with list unlocked */
tim->f(tim, tim->arg);
- rte_spinlock_lock(&priv_timer[lcore_id].list_lock);
__TIMER_STAT_ADD(pending, -1);
/* the timer was stopped or reloaded by the callback
* function, we have nothing to do here */
@@ -579,6 +598,7 @@ void rte_timer_manage(void)
}
else {
/* keep it in list and mark timer as pending */
+ rte_spinlock_lock(&priv_timer[lcore_id].list_lock);
status.state = RTE_TIMER_PENDING;
__TIMER_STAT_ADD(pending, 1);
status.owner = (int16_t)lcore_id;
@@ -586,16 +606,9 @@ void rte_timer_manage(void)
tim->status.u32 = status.u32;
__rte_timer_reset(tim, cur_time + tim->period,
tim->period, lcore_id, tim->f, tim->arg, 1);
+ rte_spinlock_unlock(&priv_timer[lcore_id].list_lock);
}
}
-
- /* update the next to expire timer value */
- priv_timer[lcore_id].pending_head.expire =
- (priv_timer[lcore_id].pending_head.sl_next[0] == NULL) ? 0 :
- priv_timer[lcore_id].pending_head.sl_next[0]->expire;
-done:
- /* job finished, unlock the list lock */
- rte_spinlock_unlock(&priv_timer[lcore_id].list_lock);
}
/* dump statistics about timers */