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 4A2E11B925 for ; Fri, 14 Dec 2018 10:53:16 +0100 (CET) Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A2A5E7F3EC; Fri, 14 Dec 2018 09:53:15 +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 11DD81852A; Fri, 14 Dec 2018 09:53:13 +0000 (UTC) From: Maxime Coquelin To: Matthias Gatto Cc: dev@dpdk.org, tiwei.bie@intel.com, zhihong.wang@intel.com References: <1544112007-23177-1-git-send-email-matthias.gatto@outscale.com> <1f9db33f-b281-b794-bc00-ad83490c2fbd@redhat.com> Message-ID: <1fa47f8c-18a1-fbb4-1794-3324126cf9f1@redhat.com> Date: Fri, 14 Dec 2018 10:53:11 +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: <1f9db33f-b281-b794-bc00-ad83490c2fbd@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Fri, 14 Dec 2018 09:53:15 +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 09:53:16 -0000 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 > Maxime