> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Michal Jastrzebski > Sent: Thursday, September 25, 2014 1:56 PM > To: dev at dpdk.org > Subject: [dpdk-dev] [PATCH v2] Change alarm cancel function to thread-safe: > > Change alarm cancel function to thread-safe. > It eliminates a race between threads using rte_alarm_cancel and > rte_alarm_set. > > Signed-off-by: Pawel Wodkowski <pawelx.wodkowski at intel.com> > Reviewed-by: Michal Jastrzebski <michalx.k.jastrzebski at intel.com> > > --- > lib/librte_eal/common/include/rte_alarm.h | 3 +- > lib/librte_eal/linuxapp/eal/eal_alarm.c | 68 > ++++++++++++++++++----------- > 2 files changed, 45 insertions(+), 26 deletions(-) > > diff --git a/lib/librte_eal/common/include/rte_alarm.h > b/lib/librte_eal/common/include/rte_alarm.h > index d451522..e7cbaef 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 its > execution. > * > * @param cb_fn > * alarm callback > diff --git a/lib/librte_eal/linuxapp/eal/eal_alarm.c > b/lib/librte_eal/linuxapp/eal/eal_alarm.c > index 480f0cb..ea8dfb4 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 +204,50 @@ rte_eal_alarm_cancel(rte_eal_alarm_callback cb_fn, void > *cb_arg) > { > struct alarm_entry *ap, *ap_prev; > int count = 0; > + int executing; > > if (!cb_fn) > 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 (pthread_equal(ap->executing_id, > pthread_self()) == 0) > + executing++; > + > + 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++; > + } > + ap_prev = ap; > + } > + rte_spinlock_unlock(&alarm_list_lk); > + } while (executing != 0); > + > return count; > } > - > -- > 1.7.9.5
Acked-by: Konstantin Ananyev <konstantin.ananyev at intel.com>
