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[104.188.17.28]) by smtp.gmail.com with ESMTPSA id y7sm12371229pfq.159.2020.03.11.16.27.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Mar 2020 16:27:10 -0700 (PDT) Date: Wed, 11 Mar 2020 16:27:07 -0700 From: Bjorn Andersson To: Loic Pallardy Cc: ohad@wizery.com, mathieu.poirier@linaro.org, linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org, arnaud.pouliquen@st.com, benjamin.gaignard@linaro.org, fabien.dessenne@st.com, s-anna@ti.com Subject: Re: [RFC 1/2] remoteproc: sysfs: authorize rproc shutdown when rproc is crashed Message-ID: <20200311232707.GA1214176@minitux> References: <1583924072-20648-1-git-send-email-loic.pallardy@st.com> <1583924072-20648-2-git-send-email-loic.pallardy@st.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1583924072-20648-2-git-send-email-loic.pallardy@st.com> User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 11 Mar 03:54 PDT 2020, Loic Pallardy wrote: > 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. > 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. > 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 = rproc_stop(rproc, false); > + ret = rproc_stop(rproc, rproc->state == RPROC_CRASHED); Afaict this is unrelated to the problem you're describing in the commit message. > 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 != RPROC_RUNNING) > + if (rproc->state != RPROC_RUNNING && rproc->state != RPROC_CRASHED) Analogous to the problem reported by Alex here https://patchwork.kernel.org/patch/11413161/ the handling of stop seems racy. 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()... With Alex fix that should be less of a problem though... Regards, Bjorn > return -EINVAL; > > rproc_shutdown(rproc); > -- > 2.7.4 >