From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by dpdk.org (Postfix) with ESMTP id 407866896 for ; Wed, 24 Sep 2014 17:13:18 +0200 (CEST) Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga101.fm.intel.com with ESMTP; 24 Sep 2014 08:18:24 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.04,589,1406617200"; d="scan'208";a="596223344" Received: from irsmsx101.ger.corp.intel.com ([163.33.3.153]) by fmsmga001.fm.intel.com with ESMTP; 24 Sep 2014 08:18:23 -0700 Received: from irsmsx105.ger.corp.intel.com ([169.254.7.158]) by IRSMSX101.ger.corp.intel.com ([169.254.1.194]) with mapi id 14.03.0195.001; Wed, 24 Sep 2014 16:18:10 +0100 From: "Ananyev, Konstantin" To: "Jastrzebski, MichalX K" , "dev@dpdk.org" Thread-Topic: [dpdk-dev] [PATCH] Change alarm cancel function to thread-safe. Thread-Index: AQHP1z/R3alMUtTchEOehHad5SXhxJwQYVhQ Date: Wed, 24 Sep 2014 15:18:10 +0000 Message-ID: <2601191342CEEE43887BDE71AB9772582136DDF1@IRSMSX105.ger.corp.intel.com> References: <1411484549-711-1-git-send-email-michalx.k.jastrzebski@intel.com> In-Reply-To: <1411484549-711-1-git-send-email-michalx.k.jastrzebski@intel.com> Accept-Language: en-IE, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [163.33.239.181] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: Re: [dpdk-dev] [PATCH] Change alarm cancel function to 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, 24 Sep 2014 15:13:19 -0000 Hi Michal, > -----Original Message----- > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Michal Jastrzebski > Sent: Tuesday, September 23, 2014 4:02 PM > To: dev@dpdk.org > Subject: [dpdk-dev] [PATCH] Change alarm cancel function to thread-safe. >=20 > It eliminates a race between threads using rte_alarm_cancel and rte_alarm= _set. >=20 > Signed-off-by: Pawel Wodkowski > Reviewed-by: Michal Jastrzebski The patch looks good, but I think it is incomplete. At rte_eal_alarm_set(), for newly allocated alarm_entry we never reset valu= e of 'executing' to zero. Yes, it seems that problem is not new, and was here for a while. Probably the easiest way to fix it: @@ -150,7 +150,7 @@ rte_eal_alarm_set(uint64_t us, rte_eal_alarm_callback c= b_fn, void *cb_arg) if (us < 1 || us > (UINT64_MAX - US_PER_S) || cb_fn =3D=3D NULL) return -EINVAL; - new_alarm =3D rte_malloc(NULL, sizeof(*new_alarm), 0); + new_alarm =3D rte_zmalloc(NULL, sizeof(*new_alarm), 0); if (new_alarm =3D=3D NULL) return -ENOMEM; Plus two nits, see below. Thanks Konstantin > --- > lib/librte_eal/common/include/rte_alarm.h | 3 +- > lib/librte_eal/linuxapp/eal/eal_alarm.c | 68 +++++++++++++++++++----= ------ > 2 files changed, 46 insertions(+), 25 deletions(-) >=20 > diff --git a/lib/librte_eal/common/include/rte_alarm.h b/lib/librte_eal/c= ommon/include/rte_alarm.h > index d451522..f5f7de4 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_a= rg); >=20 > /** > - * Function to cancel an alarm callback which has been registered before= . > + * Function to cancel an alarm callback which has been registered before= . If > + * used ouside alarm callback it wait for all callbacks to finish its ex= ecution. s/ouside/outside/ > * > * @param cb_fn > * alarm callback > diff --git a/lib/librte_eal/linuxapp/eal/eal_alarm.c b/lib/librte_eal/lin= uxapp/eal/eal_alarm.c > index 480f0cb..0561dbf 100644 > --- a/lib/librte_eal/linuxapp/eal/eal_alarm.c > +++ b/lib/librte_eal/linuxapp/eal/eal_alarm.c > @@ -69,12 +69,14 @@ 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; > }; >=20 > static LIST_HEAD(alarm_list, alarm_entry) alarm_list =3D LIST_HEAD_INITI= ALIZER(); > static rte_spinlock_t alarm_list_lk =3D RTE_SPINLOCK_INITIALIZER; >=20 > + > static struct rte_intr_handle intr_handle =3D {.fd =3D -1 }; > static int handler_registered =3D 0; > static void eal_alarm_callback(struct rte_intr_handle *hdl, void *arg); > @@ -108,11 +110,14 @@ eal_alarm_callback(struct rte_intr_handle *hdl __rt= e_unused, > (ap->time.tv_sec < now.tv_sec || (ap->time.tv_sec =3D=3D now.tv_sec &= & > ap->time.tv_usec <=3D now.tv_usec))){ > ap->executing =3D 1; > + ap->executing_id =3D pthread_self(); > rte_spinlock_unlock(&alarm_list_lk); >=20 > ap->cb_fn(ap->cb_arg); >=20 > rte_spinlock_lock(&alarm_list_lk); > + ap->executing =3D 0; > + I don't think you need: ap->executing =3D 0 here. You are going to free ap anyway.=20 > LIST_REMOVE(ap, next); > rte_free(ap); > } > @@ -156,7 +161,6 @@ rte_eal_alarm_set(uint64_t us, rte_eal_alarm_callback= cb_fn, void *cb_arg) > new_alarm->cb_arg =3D cb_arg; > new_alarm->time.tv_usec =3D (now.tv_usec + us) % US_PER_S; > new_alarm->time.tv_sec =3D now.tv_sec + ((now.tv_usec + us) / US_PER_S)= ; > - new_alarm->executing =3D 0; >=20 > rte_spinlock_lock(&alarm_list_lk); > if (!handler_registered) { > @@ -202,34 +206,50 @@ rte_eal_alarm_cancel(rte_eal_alarm_callback cb_fn, = void *cb_arg) > { > struct alarm_entry *ap, *ap_prev; > int count =3D 0; > + int executing; >=20 > if (!cb_fn) > return -1; >=20 > - rte_spinlock_lock(&alarm_list_lk); > - /* remove any matches at the start of the list */ > - while ((ap =3D LIST_FIRST(&alarm_list)) !=3D NULL && > - cb_fn =3D=3D ap->cb_fn && ap->executing =3D=3D 0 && > - (cb_arg =3D=3D (void *)-1 || cb_arg =3D=3D ap->cb_arg)) { > - LIST_REMOVE(ap, next); > - rte_free(ap); > - count++; > - } > - ap_prev =3D 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 =3D=3D ap->cb_fn && ap->executing =3D=3D 0 && > + do { > + executing =3D 0; > + rte_spinlock_lock(&alarm_list_lk); > + /* remove any matches at the start of the list */ > + while ((ap =3D LIST_FIRST(&alarm_list)) !=3D NULL && > + cb_fn =3D=3D ap->cb_fn && > (cb_arg =3D=3D (void *)-1 || cb_arg =3D=3D ap->cb_arg)) { > - LIST_REMOVE(ap,next); > - rte_free(ap); > - count++; > - ap =3D ap_prev; > + > + if (ap->executing =3D=3D 0) { > + LIST_REMOVE(ap, next); > + rte_free(ap); > + count++; > + } else { > + if (pthread_equal(ap->executing_id, pthread_self()) =3D=3D 0) > + executing++; > + > + break; > + } > } > ap_prev =3D 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 =3D=3D ap->cb_fn && > + (cb_arg =3D=3D (void *)-1 || cb_arg =3D=3D ap->cb_arg)) { > + > + if (ap->executing =3D=3D 0) { > + LIST_REMOVE(ap, next); > + rte_free(ap); > + count++; > + ap =3D ap_prev; > + } else if (pthread_equal(ap->executing_id, pthread_self()) =3D=3D 0) > + executing++; > + } > + ap_prev =3D ap; > + } > + rte_spinlock_unlock(&alarm_list_lk); > + } while (executing !=3D 0); > + > return count; > } > - > -- > 1.7.9.5