From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.tuxdriver.com (charlotte.tuxdriver.com [70.61.120.58]) by dpdk.org (Postfix) with ESMTP id 24633E82 for ; Wed, 1 Oct 2014 17:06:15 +0200 (CEST) Received: from nat-pool-rdu-u.redhat.com ([66.187.233.203] helo=localhost) by smtp.tuxdriver.com with esmtpsa (TLSv1:AES128-SHA:128) (Exim 4.63) (envelope-from ) id 1XZLa6-0000vJ-8h; Wed, 01 Oct 2014 11:12:59 -0400 Date: Wed, 1 Oct 2014 11:12:35 -0400 From: Neil Horman To: Pawel Wodkowski Message-ID: <20141001151235.GD24028@localhost.localdomain> References: <1412173222-22391-1-git-send-email-pawelx.wodkowski@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1412173222-22391-1-git-send-email-pawelx.wodkowski@intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-Spam-Score: -2.9 (--) X-Spam-Status: No Cc: dev@dpdk.org Subject: Re: [dpdk-dev] [PATCH v3] alarms: Change alarm cancel function to be thread-safe X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 01 Oct 2014 15:06:15 -0000 On Wed, Oct 01, 2014 at 03:20:22PM +0100, Pawel Wodkowski wrote: > v3: > Set rte_errno inside rte_alarm_cancel() to inform caller about canceling result. > > v2: > Eliminate a race between rte_alarm_set() used in context of executing callback > function and other threads that use rte_alarm_cancel(). > > Signed-off-by: Pawel Wodkowski > --- > lib/librte_eal/common/include/rte_alarm.h | 12 ++++- > lib/librte_eal/linuxapp/eal/eal_alarm.c | 83 ++++++++++++++++++++--------- > 2 files changed, 68 insertions(+), 27 deletions(-) > > diff --git a/lib/librte_eal/common/include/rte_alarm.h b/lib/librte_eal/common/include/rte_alarm.h > index d451522..d5d4e9d 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 cancelation 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 480f0cb..4801650 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; > } > - > -- > 1.7.9.5 > > Much better, thanks! Acked-by: Neil Horman