From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id 4CB861BA00; Fri, 14 Dec 2018 11:08:57 +0100 (CET) Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9E694307EA84; Fri, 14 Dec 2018 10:08:56 +0000 (UTC) Received: from [10.36.112.58] (ovpn-112-58.ams2.redhat.com [10.36.112.58]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B404D1054FD2; Fri, 14 Dec 2018 10:08:54 +0000 (UTC) To: Matthias Gatto Cc: dev@dpdk.org, tiwei.bie@intel.com, zhihong.wang@intel.com, stable@dpdk.org References: <1544112007-23177-1-git-send-email-matthias.gatto@outscale.com> <1f9db33f-b281-b794-bc00-ad83490c2fbd@redhat.com> <1fa47f8c-18a1-fbb4-1794-3324126cf9f1@redhat.com> From: Maxime Coquelin Message-ID: <7a7a3181-1529-dd5f-b95f-9f8fef77fa8f@redhat.com> Date: Fri, 14 Dec 2018 11:08:52 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Fri, 14 Dec 2018 10:08:56 +0000 (UTC) Subject: Re: [dpdk-dev] [PATCH] vhost: fix race condition in fdset_add X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 14 Dec 2018 10:08:57 -0000 On 12/14/18 11:07 AM, Matthias Gatto wrote: > On Fri, Dec 14, 2018 at 10:53 AM Maxime Coquelin > wrote: >> >> >> >> On 12/14/18 10:51 AM, Maxime Coquelin wrote: >>> >>> >>> On 12/14/18 10:32 AM, Matthias Gatto wrote: >>>> On Tue, Dec 11, 2018 at 7:11 PM Maxime Coquelin >>>> wrote: >>>>> >>>>> Hi Matthias, >>>>> >>>>> On 12/6/18 5:00 PM, Matthias Gatto wrote: >>>>>> fdset_add can call fdset_shrink_nolock which call fdset_move >>>>>> concurrently to poll that is call in fdset_event_dispatch. >>>>>> >>>>>> This patch add a mutex to protect poll from been call at the same time >>>>>> fdset_add call fdset_shrink_nolock. >>>>>> >>>>>> Signed-off-by: Matthias Gatto >>>>>> --- >>>>>> lib/librte_vhost/fd_man.c | 4 ++++ >>>>>> lib/librte_vhost/fd_man.h | 1 + >>>>>> lib/librte_vhost/socket.c | 1 + >>>>>> 3 files changed, 6 insertions(+) >>>>>> >>>>>> diff --git a/lib/librte_vhost/fd_man.c b/lib/librte_vhost/fd_man.c >>>>>> index 38347ab..55d4856 100644 >>>>>> --- a/lib/librte_vhost/fd_man.c >>>>>> +++ b/lib/librte_vhost/fd_man.c >>>>>> @@ -129,7 +129,9 @@ >>>>>> pthread_mutex_lock(&pfdset->fd_mutex); >>>>>> i = pfdset->num < MAX_FDS ? pfdset->num++ : -1; >>>>>> if (i == -1) { >>>>>> + pthread_mutex_lock(&pfdset->fd_pooling_mutex); >>>>>> fdset_shrink_nolock(pfdset); >>>>>> + pthread_mutex_unlock(&pfdset->fd_pooling_mutex); >>>>>> i = pfdset->num < MAX_FDS ? pfdset->num++ : -1; >>>>>> if (i == -1) { >>>>>> pthread_mutex_unlock(&pfdset->fd_mutex); >>>>>> @@ -246,7 +248,9 @@ >>>>>> numfds = pfdset->num; >>>>>> pthread_mutex_unlock(&pfdset->fd_mutex); >>>>>> >>>>>> + pthread_mutex_lock(&pfdset->fd_pooling_mutex); >>>>>> val = poll(pfdset->rwfds, numfds, 1000 /* millisecs */); >>>>>> + pthread_mutex_unlock(&pfdset->fd_pooling_mutex); >>>>> >>>>> Any reason we cannot use the existing fd_mutex? >>>> >>>> yes, using the existing fd_mutex would block fdset_add during the >>>> polling in >>>> fdset_event_dispatch. >>>> >>>> here fd_pooling_mutex block only fdset_shrink_nolock inside >>>> fdset_add which happen only in very rare occasions. >>> >>> >>> Thanks for the clarification: >>> >>> Reviewed-by: Maxime Coquelin >> >> I guess we need to cc: stable, can you help with specifying which >> commit it fixes? >> >> Thanks in advance, >> Maxime >> > > this commit 1b815b89599cdd9b54e5aa70f5b97088225b2bcc > which was actually a commit I've made, sorry for that. Don't be sorry, your contributions are welcome! I'll fixup the commit message with adding Fixes line. Thanks, Maxime > Thanks for the review, > > Matthias >>> Maxime