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From:   Peng Fan <peng.fan@nxp.com>
To:     "S.J. Wang" <shengjiu.wang@nxp.com>,
        "andersson@kernel.org" <andersson@kernel.org>,
        "mathieu.poirier@linaro.org" <mathieu.poirier@linaro.org>,
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CC:     "linux-remoteproc@vger.kernel.org" <linux-remoteproc@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "shengjiu.wang@gmail.com" <shengjiu.wang@gmail.com>
Subject: RE: [PATCH] remoteproc: imx_dsp_rproc: Add mutex protection for
 workqueue
Thread-Topic: [PATCH] remoteproc: imx_dsp_rproc: Add mutex protection for
 workqueue
Thread-Index: AQHY0a9PUexT6xrsH0SQuEOAj4mH/K30o4tA
Date:   Wed, 28 Sep 2022 10:22:32 +0000
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> Subject: [PATCH] remoteproc: imx_dsp_rproc: Add mutex protection for
> workqueue
>=20
> 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.
>=20
> 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
>=20
> Add mutex protection in imx_dsp_rproc_vq_work(), if the state is not
> running, then just skip calling rproc_vq_interrupt().
>=20
> Also the flush workqueue operation can't be added in rproc stop for same
> reason.
>=20
> Fixes: ec0e5549f358 ("remoteproc: imx_dsp_rproc: Add remoteproc driver
> for DSP on i.MX")
> Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>

Reviewed-by: Peng Fan <peng.fan@nxp.com>

I also give a look at other drivers, seems almost all drivers use rproc_vq_=
interrupt
has same issue, should use mutex to protect the mbox rx callback.

Regards,
Peng.

> ---
>  drivers/remoteproc/imx_dsp_rproc.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
>=20
> 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 =3D rproc->dev.parent;
>  	int ret =3D 0;
>=20
> -	/* Make sure work is finished */
> -	flush_work(&priv->rproc_work);
> -
>  	if (rproc->state =3D=3D RPROC_CRASHED) {
>  		priv->flags &=3D ~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 =3D container_of(work, struct
> imx_dsp_rproc,
>  						  rproc_work);
> +	struct rproc *rproc =3D priv->rproc;
> +
> +	mutex_lock(&rproc->lock);
> +
> +	if (rproc->state !=3D RPROC_RUNNING)
> +		goto unlock_mutex;
>=20
>  	rproc_vq_interrupt(priv->rproc, 0);
>  	rproc_vq_interrupt(priv->rproc, 1);
> +
> +unlock_mutex:
> +	mutex_unlock(&rproc->lock);
>  }
>=20
>  /**
> --
> 2.34.1