From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Loic PALLARDY Subject: RE: [RFC 1/2] remoteproc: sysfs: authorize rproc shutdown when rproc is crashed Date: Thu, 12 Mar 2020 08:12:32 +0000 Message-ID: <1161f034ddc64d6aa782f06c3c4996cd@SFHDAG7NODE2.st.com> References: <1583924072-20648-1-git-send-email-loic.pallardy@st.com> <1583924072-20648-2-git-send-email-loic.pallardy@st.com> <20200311232707.GA1214176@minitux> In-Reply-To: <20200311232707.GA1214176@minitux> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 To: Bjorn Andersson Cc: "ohad@wizery.com" , "mathieu.poirier@linaro.org" , "linux-remoteproc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Arnaud POULIQUEN , "benjamin.gaignard@linaro.org" , "Fabien DESSENNE , s-anna@ti.com" List-ID: Hi Bjorn, > -----Original Message----- > From: Bjorn Andersson > Sent: jeudi 12 mars 2020 00:27 > To: Loic PALLARDY > Cc: ohad@wizery.com; mathieu.poirier@linaro.org; linux- > remoteproc@vger.kernel.org; linux-kernel@vger.kernel.org; Arnaud > POULIQUEN ; benjamin.gaignard@linaro.org; > Fabien DESSENNE ; s-anna@ti.com > Subject: Re: [RFC 1/2] remoteproc: sysfs: authorize rproc shutdown when > rproc is crashed >=20 > On Wed 11 Mar 03:54 PDT 2020, Loic Pallardy wrote: >=20 > > When remoteproc recovery is disabled and rproc crashed, user space > > client has no way to reboot co-processor except by a complete platform > > reboot. > > Indeed rproc_shutdown() is called by sysfs state_store() only is rproc > > state is RPROC_RUNNING. > > > > This patch offers the possibility to shutdown the co-processor if > > it is in RPROC_CRASHED state and so to restart properly co-processor > > from sysfs interface. > > >=20 > I did recently run into a similar problem when I fed my remoteproc > faulty firmware, which lead to it recovering immediately upon boot. The > amount of time spent in !CRASHED state was minimal, so I didn't have any > way to stop the remoteproc. >=20 > > Signed-off-by: Loic Pallardy > > --- > > drivers/remoteproc/remoteproc_core.c | 2 +- > > drivers/remoteproc/remoteproc_sysfs.c | 2 +- > > 2 files changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/remoteproc/remoteproc_core.c > b/drivers/remoteproc/remoteproc_core.c > > index 097f33e4f1f3..7ac87a75cd1b 100644 > > --- a/drivers/remoteproc/remoteproc_core.c > > +++ b/drivers/remoteproc/remoteproc_core.c > > @@ -1812,7 +1812,7 @@ void rproc_shutdown(struct rproc *rproc) > > if (!atomic_dec_and_test(&rproc->power)) > > goto out; > > > > - ret =3D rproc_stop(rproc, false); > > + ret =3D rproc_stop(rproc, rproc->state =3D=3D RPROC_CRASHED); >=20 > Afaict this is unrelated to the problem you're describing in the commit > message. Right, it is because now rproc_shudown could be could in a context where rp= roc is in RPROC_CRASHED state and so false is no more the default value. Could be split in another patch. >=20 > > if (ret) { > > atomic_inc(&rproc->power); > > goto out; > > diff --git a/drivers/remoteproc/remoteproc_sysfs.c > b/drivers/remoteproc/remoteproc_sysfs.c > > index 7f8536b73295..1029458a4678 100644 > > --- a/drivers/remoteproc/remoteproc_sysfs.c > > +++ b/drivers/remoteproc/remoteproc_sysfs.c > > @@ -101,7 +101,7 @@ static ssize_t state_store(struct device *dev, > > if (ret) > > dev_err(&rproc->dev, "Boot failed: %d\n", ret); > > } else if (sysfs_streq(buf, "stop")) { > > - if (rproc->state !=3D RPROC_RUNNING) > > + if (rproc->state !=3D RPROC_RUNNING && rproc->state !=3D > RPROC_CRASHED) >=20 > Analogous to the problem reported by Alex here > https://patchwork.kernel.org/patch/11413161/ the handling of stop seems > racy. >=20 > In particular, I believe you're failing to protect against a race > with a just scheduled rproc_crash_handler_work() being executed after > the mutex_unlock() in rproc_shutdown()... >=20 > With Alex fix that should be less of a problem though... Thanks for pointing me Alex's patch. But I don't think it is exactly the sa= me issue as it concerns the recovery procedure itself. In my case, the recovery is disabled. On a crash detection, rproc->state is= simply set to RPROC_CRASHED and recovery is not triggered. Without client action, rproc will stay forever in RPROC_CRASHED test. Today without this modification, it is not possible to shutdown rproc prope= rly, putting coprocessor under reset, disabling clocks... Regards, Loic >=20 > Regards, > Bjorn >=20 > > return -EINVAL; > > > > rproc_shutdown(rproc); > > -- > > 2.7.4 > >