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[68.147.0.187]) by smtp.gmail.com with ESMTPSA id l10-20020a170903120a00b001780a528540sm4118002plh.93.2022.09.28.10.20.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Sep 2022 10:20:45 -0700 (PDT) Date: Wed, 28 Sep 2022 11:20:42 -0600 From: Mathieu Poirier To: Shengjiu Wang Cc: andersson@kernel.org, arnaud.pouliquen@foss.st.com, linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org, shengjiu.wang@gmail.com Subject: Re: [PATCH] remoteproc: imx_dsp_rproc: Add mutex protection for workqueue Message-ID: <20220928172042.GB2990524@p14s> References: <1664192893-14487-1-git-send-email-shengjiu.wang@nxp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1664192893-14487-1-git-send-email-shengjiu.wang@nxp.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 26, 2022 at 07:48:13PM +0800, Shengjiu Wang wrote: > The workqueue may execute late even after remoteproc is stopped or > stopping, some resources (rpmsg device and endpoint) have been > released in rproc_stop_subdevices(), then rproc_vq_interrupt() > access these resources will cause kennel dump. > > Call trace: > virtqueue_add_split+0x1ac/0x560 > virtqueue_add_inbuf+0x4c/0x60 > rpmsg_recv_done+0x15c/0x294 > vring_interrupt+0x6c/0xa4 > rproc_vq_interrupt+0x30/0x50 > imx_dsp_rproc_vq_work+0x24/0x40 [imx_dsp_rproc] > process_one_work+0x1d0/0x354 > worker_thread+0x13c/0x470 > kthread+0x154/0x160 > ret_from_fork+0x10/0x20 > > Add mutex protection in imx_dsp_rproc_vq_work(), if the state is > not running, then just skip calling rproc_vq_interrupt(). > > Also the flush workqueue operation can't be added in rproc stop > for same reason. > > Fixes: ec0e5549f358 ("remoteproc: imx_dsp_rproc: Add remoteproc driver for DSP on i.MX") > Signed-off-by: Shengjiu Wang > --- > drivers/remoteproc/imx_dsp_rproc.c | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/drivers/remoteproc/imx_dsp_rproc.c b/drivers/remoteproc/imx_dsp_rproc.c > index 899aa8dd12f0..95da1cbefacf 100644 > --- a/drivers/remoteproc/imx_dsp_rproc.c > +++ b/drivers/remoteproc/imx_dsp_rproc.c > @@ -347,9 +347,6 @@ static int imx_dsp_rproc_stop(struct rproc *rproc) > struct device *dev = rproc->dev.parent; > int ret = 0; > > - /* Make sure work is finished */ > - flush_work(&priv->rproc_work); > - The kernel documentation for this function [1] indicate that once it returns there will no more jobs to process in that queue, _unless_ another job has been queued _after_ the flush has started. What I suspect is happening here is that a new job is queued between the time flush_work() returns and the remote processor is switched off, something that should not be happening since all the subdevices have been stopped in rproc_stop_subdevices(). [1]. https://elixir.bootlin.com/linux/v6.0-rc7/source/kernel/workqueue.c#L3092 > if (rproc->state == RPROC_CRASHED) { > priv->flags &= ~REMOTE_IS_READY; > return 0; > @@ -432,9 +429,18 @@ static void imx_dsp_rproc_vq_work(struct work_struct *work) > { > struct imx_dsp_rproc *priv = container_of(work, struct imx_dsp_rproc, > rproc_work); > + struct rproc *rproc = priv->rproc; > + > + mutex_lock(&rproc->lock); > + > + if (rproc->state != RPROC_RUNNING) > + goto unlock_mutex; > > rproc_vq_interrupt(priv->rproc, 0); > rproc_vq_interrupt(priv->rproc, 1); These are not guaranteed to be atomic and sleeping with the mutex held is guaranteed to deadlock the system. Thanks, Mathieu > + > +unlock_mutex: > + mutex_unlock(&rproc->lock); > } > > /** > -- > 2.34.1 >