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 D6B6D4F9C for ; Tue, 27 Nov 2018 14:25:38 +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 DB3F7307D864; Tue, 27 Nov 2018 13:25:37 +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 019E75DF27; Tue, 27 Nov 2018 13:25:32 +0000 (UTC) To: "Stojaczyk, Dariusz" Cc: "gaetan.rivet@6wind.com" , "thomas@monjalon.net" , "stable@dpdk.org" , Maxime Coquelin References: <20181121193827.62540-1-dariusz.stojaczyk@intel.com> <20181123154328.97021-1-dariusz.stojaczyk@intel.com> <2bee53eb-a3e3-341c-8274-3f745d99b77c@redhat.com> From: Kevin Traynor Organization: Red Hat Message-ID: <4a68d9cf-26b1-4c7b-f643-426d1d8ac86b@redhat.com> Date: Tue, 27 Nov 2018 13:25:31 +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 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Tue, 27 Nov 2018 13:25:38 +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 13:25:39 -0000 On 11/27/2018 01:03 PM, Stojaczyk, Dariusz wrote: > > >> -----Original Message----- >> From: Kevin Traynor [mailto:ktraynor@redhat.com] >> Sent: Tuesday, November 27, 2018 12:40 PM >> To: Stojaczyk, Dariusz ; Maxime Coquelin >> >> Cc: gaetan.rivet@6wind.com; thomas@monjalon.net; stable@dpdk.org >> Subject: Re: [dpdk-dev] [PATCH v3] dev: don't remove devargs that are still >> referenced >> >> 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. > > Kevin, I just tried rebasing this patch on 18.08, but the relevant code in 18.08 is just too much of a mess and I prefer not to touch it. No, problem, thanks for checking it, Kevin. > Sorry, > D. > >> >> >>> 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 >