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 C889158F6 for ; Tue, 27 Nov 2018 12:40:30 +0100 (CET) Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 031033097074; Tue, 27 Nov 2018 11:40:30 +0000 (UTC) Received: from ktraynor.remote.csb (ovpn-117-230.ams2.redhat.com [10.36.117.230]) by smtp.corp.redhat.com (Postfix) with ESMTP id CBC656266E; Tue, 27 Nov 2018 11:40:24 +0000 (UTC) To: "Stojaczyk, Dariusz" , Maxime Coquelin Cc: "gaetan.rivet@6wind.com" , "thomas@monjalon.net" , "stable@dpdk.org" References: <20181121193827.62540-1-dariusz.stojaczyk@intel.com> <20181123154328.97021-1-dariusz.stojaczyk@intel.com> From: Kevin Traynor Organization: Red Hat Message-ID: <2bee53eb-a3e3-341c-8274-3f745d99b77c@redhat.com> Date: Tue, 27 Nov 2018 11:40:23 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Tue, 27 Nov 2018 11:40:30 +0000 (UTC) Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH v3] dev: don't remove devargs that are still referenced X-BeenThere: stable@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches for DPDK stable branches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 27 Nov 2018 11:40:31 -0000 On 11/23/2018 09:45 PM, Stojaczyk, Dariusz wrote: > > >> -----Original Message----- >> From: Maxime Coquelin [mailto:maxime.coquelin@redhat.com] >> Sent: Friday, November 23, 2018 6:05 PM >> To: Stojaczyk, Dariusz ; dev@dpdk.org >> Cc: gaetan.rivet@6wind.com; thomas@monjalon.net >> Subject: Re: [dpdk-dev] [PATCH v3] dev: don't remove devargs that are still >> referenced >> >> Hi, >> >> On 11/23/18 4:43 PM, Darek Stojaczyk wrote: >>> Even if a device failed to plug, it's still a device >>> object that references the devargs. Those devargs will >>> be freed automatically together with the device, but >>> freeing them any earlier - like it's done in the hotplug >>> error handling path right now - will give us a dangling >>> pointer and a segfault scenario. >>> >>> Consider the following case: >>> * secondary process receives the hotplug request IPC message >>> * devargs are either created or updated >>> * the bus is scanned >>> * a new device object is created with the latest devargs >>> * the device can't be plugged for whatever reason, >>> bus->plug returns error >>> * the devargs are freed, even though they're still referenced >>> by the device object on the bus >>> >>> For PCI devices, the generic device name comes from >>> a buffer within the devargs. Freeing those will make >>> EAL segfault whenever the device name is checked. >>> >>> This patch just prevents the hotplug error handling >>> path from removing the devargs when there's a device >>> that references them. This is done by simply exiting >>> early from the hotplug function. As mentioned in the >>> beginning, those devargs will be freed later, together >>> with the device itself. >>> >>> Fixes: 7e8b26650146 ("eal: fix hotplug add / remove") >> >> Should you also cc stable? >> Above commit is in since v17.08. >> > > Hi Maxime, > > Stable could use a similar patch, but not exactly this one as it is now. I'll resubmit for stable once the one here gets approved. > Hi Darek, feel free to send patch to stable@dpdk.org with [18.08] subject prefix, now that this is applied on master, thanks. > Thank you, > D. > >>> Cc: gaetan.rivet@6wind.com >>> Cc: thomas@monjalon.net >>> >>> Signed-off-by: Darek Stojaczyk >>> --- >>> Changes since v2: >>> * added an extra comment (Gaetan) >>> >>> Changes since v1: >>> * described the failing scenario in commit msg (Thomas) >>> >>> lib/librte_eal/common/eal_common_dev.c | 13 ++++++++----- >>> 1 file changed, 8 insertions(+), 5 deletions(-) >>> >>> diff --git a/lib/librte_eal/common/eal_common_dev.c >> b/lib/librte_eal/common/eal_common_dev.c >>> index 1fdc9ab17..d7950bc9a 100644 >>> --- a/lib/librte_eal/common/eal_common_dev.c >>> +++ b/lib/librte_eal/common/eal_common_dev.c >>> @@ -166,14 +166,17 @@ local_dev_probe(const char *devargs, struct >> rte_device **new_dev) >>> ret = -ENODEV; >>> goto err_devarg; >>> } >>> + /* Since there is a matching device, it is now its responsibility >>> + * to manage the devargs we've just inserted. From this point >>> + * those devargs shouldn't be removed manually anymore. >>> + */ >>> >>> ret = dev->bus->plug(dev); >>> if (ret) { >>> - if (rte_dev_is_probed(dev)) /* if already succeeded earlier >> */ >>> - return ret; /* no rollback */ >>> - RTE_LOG(ERR, EAL, "Driver cannot attach the device (%s)\n", >>> - dev->name); >>> - goto err_devarg; >>> + if (!rte_dev_is_probed(dev)) /* if hasn't succeeded earlier */ >>> + RTE_LOG(ERR, EAL, "Driver cannot attach the device >> (%s)\n", >>> + dev->name); >>> + return ret; >>> } >>> >>> *new_dev = dev; >>> >> >> Other than that, it looks good to me: >> Acked-by: Maxime Coquelin >> >> Regards, >> Maxime