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[68.147.8.254]) by smtp.gmail.com with ESMTPSA id n188sm29570370pga.84.2020.01.17.14.52.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 17 Jan 2020 14:52:19 -0800 (PST) Date: Fri, 17 Jan 2020 15:52:17 -0700 From: Mathieu Poirier To: =?iso-8859-1?Q?Cl=E9ment?= Leger Cc: Arnaud Pouliquen , Ohad Ben-Cohen , Bjorn Andersson , linux-remoteproc , linux-kernel Subject: Re: [PATCH] remoteproc: Add support for predefined notifyids Message-ID: <20200117225217.GA27535@xps15> References: <20200115102142.11229-1-cleger@kalray.eu> <088ceab9-f135-6e70-dcf6-f75ec46110b1@st.com> <79048597.12371594.1579098506802.JavaMail.zimbra@kalray.eu> <612100872.12377996.1579101063237.JavaMail.zimbra@kalray.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <612100872.12377996.1579101063237.JavaMail.zimbra@kalray.eu> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hey guys, On Wed, Jan 15, 2020 at 04:11:03PM +0100, Clément Leger wrote: > > > ----- On 15 Jan, 2020, at 16:09, Arnaud Pouliquen arnaud.pouliquen@st.com wrote: > > > On 1/15/20 3:28 PM, Clément Leger wrote: > >> Hi Arnaud, > >> > >> ----- On 15 Jan, 2020, at 15:06, Arnaud Pouliquen arnaud.pouliquen@st.com wrote: > >> > >>> Hi Clément, > >>> > >>> On 1/15/20 11:21 AM, Clement Leger wrote: > >>>> In order to support preallocated notify ids, if their value is > >>>> equal to FW_RSC_NOTIFY_ID_ANY, then do no allocate a notify id > >>>> dynamically but try to allocate the requested one. This is useful when > >>>> using custom ids to bind them to custom vendor resources. For instance, > >>>> it allow to assign a group of queues to a specific interrupti in order > >>>> to dispatch notifications. > >>>> > >>>> Signed-off-by: Clement Leger > >>>> --- > >>>> drivers/remoteproc/remoteproc_core.c | 27 +++++++++++++++++++-------- > >>>> include/linux/remoteproc.h | 1 + > >>>> 2 files changed, 20 insertions(+), 8 deletions(-) > >>>> > >>>> diff --git a/drivers/remoteproc/remoteproc_core.c > >>>> b/drivers/remoteproc/remoteproc_core.c > >>>> index 307df98347ba..b1485fcd0f11 100644 > >>>> --- a/drivers/remoteproc/remoteproc_core.c > >>>> +++ b/drivers/remoteproc/remoteproc_core.c > >>>> @@ -351,14 +351,27 @@ int rproc_alloc_vring(struct rproc_vdev *rvdev, int i) > >>>> /* > >>>> * Assign an rproc-wide unique index for this vring > >>>> * TODO: assign a notifyid for rvdev updates as well > >>>> - * TODO: support predefined notifyids (via resource table) > >>>> */ > >>>> - ret = idr_alloc(&rproc->notifyids, rvring, 0, 0, GFP_KERNEL); > >>>> - if (ret < 0) { > >>>> - dev_err(dev, "idr_alloc failed: %d\n", ret); > >>>> - return ret; > >>>> + if (rsc->vring[i].notifyid == FW_RSC_NOTIFY_ID_ANY) { > >>>> + ret = idr_alloc(&rproc->notifyids, rvring, 0, 0, GFP_KERNEL); > >>>> + if (ret < 0) { > >>>> + dev_err(dev, "idr_alloc failed: %d\n", ret); > >>>> + return ret; > >>>> + } > >>>> + notifyid = ret; > >>>> + > >>>> + /* Let the rproc know the notifyid of this vring.*/ > >>>> + rsc->vring[i].notifyid = notifyid; > >>>> + } else { > >>>> + /* Reserve requested notify_id */ > >>>> + notifyid = rsc->vring[i].notifyid; > >>>> + ret = idr_alloc(&rproc->notifyids, rvring, notifyid, > >>>> + notifyid + 1, GFP_KERNEL); > >>>> + if (ret < 0) { > >>>> + dev_err(dev, "idr_alloc failed: %d\n", ret); > >>>> + return ret; > >>>> + } > >>>> } > >>>> - notifyid = ret; > >>>> > >>>> /* Potentially bump max_notifyid */ > >>>> if (notifyid > rproc->max_notifyid) > >>>> @@ -366,8 +379,6 @@ int rproc_alloc_vring(struct rproc_vdev *rvdev, int i) > >>>> > >>>> rvring->notifyid = notifyid; > >>>> > >>>> - /* Let the rproc know the notifyid of this vring.*/ > >>>> - rsc->vring[i].notifyid = notifyid; > >>>> return 0; > >>>> } > >>> The rproc_free_vring function resets the notifyid to -1 on free. > >>> This could generate a side effect if the resource table is not reloaded. > >> > >> Oh indeed, I did not thought of that. What would you recommend ? > >> If using -1 in free vring, notify ids will be reallocated at next > >> round. > > Regarding the code i'm not sure that it is useful to reset the notifyID to -1 on > > free. I'm not sure setting notifyid to -1 in rproc_free_vring() is such a big problem. No matter the code path I look at, if rproc_free_vring() is called something serious has happened and the resource table will be reloaded if another attempt at booting the remote processor is done. It can also be that a graceful shutdown is underway, in which case the resource table will be reloaded anyway if/when the slave is brought back in service. Let me know if I'm missing a scenario. To me the real problem is if a FW image has set the notifyids in the resource table to 0xffffffff, thinking they will be overwritten. In that case things will really south. > > In current version, on alloc, the notifyID is overwriten without check. > > And as vdev status is updated, vring struct in resource table should be > > considered as invalid > > Except if i missed a usecase/race condition... > > > >> > >> I was also worried that it would break some existing user applications > >> which uses "0" as a notify id in vring but expect the id to be > >> allocated dynamically. With my modification, it means it will try to > >> use "0" as a predefined id, leading to allocation failure. >From my point of view they will have been lucky for all this time. Even with a new version of the resource table (which I think is the right way go) cases like this will break. Thanks, Mathieu > >> > > Yes this could introduce regression for firmware that sets 0 as default value. > > Probably better to introduce this patch with a new version of the resource table > > :) > > Understood ;) > > Regards, > > Clément > > > > > Regards > > Arnaud > >>> > >>>> > >>>> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h > >>>> index 16ad66683ad0..dcae3394243e 100644 > >>>> --- a/include/linux/remoteproc.h > >>>> +++ b/include/linux/remoteproc.h > >>>> @@ -123,6 +123,7 @@ enum fw_resource_type { > >>>> }; > >>>> > >>>> #define FW_RSC_ADDR_ANY (-1) > >>>> +#define FW_RSC_NOTIFY_ID_ANY (-1)This define can also be used in > >>>> rproc_free_vring > >> > >> Indeed. > >> > >> Thanks for your review. > >> > >> Regards, > >> > >> Clément > >> > >>> > >>> Regards, > >>> Arnaud > >>>> > >>>> /** > > >>> * struct fw_rsc_carveout - physically contiguous memory request