linux-kernel - Re: [PATCH v3 15/15] remoteproc: Refactor rproc delete and cdev release path

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Message-ID: <00422e08-3acc-1e5e-3d1d-f9c332256a1f@st.com>
Date:   Wed, 9 Dec 2020 11:13:07 +0100
From:   Arnaud POULIQUEN <arnaud.pouliquen@...com>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>,
        "ohad@...ery.com" <ohad@...ery.com>,
        "bjorn.andersson@...aro.org" <bjorn.andersson@...aro.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>
CC:     "linux-remoteproc@...r.kernel.org" <linux-remoteproc@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 15/15] remoteproc: Refactor rproc delete and cdev
 release path



On 11/26/20 10:06 PM, Mathieu Poirier wrote:
> Refactor function rproc_del() and rproc_cdev_release() to take
> into account the policy specified in the device tree.
> 
> Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
> ---
>  drivers/remoteproc/remoteproc_cdev.c | 13 +++++++++++-
>  drivers/remoteproc/remoteproc_core.c | 30 ++++++++++++++++++++++++++--
>  include/linux/remoteproc.h           |  4 ++++
>  3 files changed, 44 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_cdev.c b/drivers/remoteproc/remoteproc_cdev.c
> index f7645f289563..3dfe555dfc07 100644
> --- a/drivers/remoteproc/remoteproc_cdev.c
> +++ b/drivers/remoteproc/remoteproc_cdev.c
> @@ -88,7 +88,18 @@ static int rproc_cdev_release(struct inode *inode, struct file *filp)
>  {
>  	struct rproc *rproc = container_of(inode->i_cdev, struct rproc, cdev);
>  
> -	if (rproc->cdev_put_on_release && rproc->state == RPROC_RUNNING)
> +	if (!rproc->cdev_put_on_release)
> +		return 0;
> +
> +	/*
> +	 * The application has crashed or is releasing its file handle.  Detach
> +	 * or shutdown the remote processor based on the policy specified in the
> +	 * DT.  No need to check rproc->state right away, it will be done
> +	 * in either rproc_detach() or rproc_shutdown().
> +	 */
> +	if (rproc->autonomous_on_core_shutdown)
> +		rproc_detach(rproc);
> +	else
>  		rproc_shutdown(rproc);

A reason to not propagate the return of functions?

>  
>  	return 0;
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 3d7d245edc4e..1a170103bf27 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -2294,6 +2294,22 @@ static int rproc_alloc_ops(struct rproc *rproc, const struct rproc_ops *ops)
>  	return 0;
>  }
>  
> +static void rproc_set_automation_flags(struct rproc *rproc)
> +{
> +	struct device *dev = rproc->dev.parent;
> +	struct device_node *np = dev->of_node;
> +	bool core_shutdown;
> +
> +	/*
> +	 * When function rproc_cdev_release() or rproc_del() are called and
> +	 * the remote processor has been attached to, it will be detached from
> +	 * (rather than turned off) if "autonomous-on-core-shutdown is specified
> +	 * in the DT.
> +	 */
> +	core_shutdown = of_property_read_bool(np, "autonomous-on-core-shutdown");
> +	rproc->autonomous_on_core_shutdown = core_shutdown;
> +}
> +
>  /**
>   * rproc_alloc() - allocate a remote processor handle
>   * @dev: the underlying device
> @@ -2352,6 +2368,8 @@ struct rproc *rproc_alloc(struct device *dev, const char *name,
>  	if (rproc_alloc_ops(rproc, ops))
>  		goto put_device;
>  
> +	rproc_set_automation_flags(rproc);
> +
>  	/* Assign a unique device index and name */
>  	rproc->index = ida_simple_get(&rproc_dev_index, 0, 0, GFP_KERNEL);
>  	if (rproc->index < 0) {
> @@ -2435,8 +2453,16 @@ int rproc_del(struct rproc *rproc)
>  	if (!rproc)
>  		return -EINVAL;
>  
> -	/* TODO: make sure this works with rproc->power > 1 */
> -	rproc_shutdown(rproc);
> +	/*
> +	 * TODO: make sure this works with rproc->power > 1
> +	 *
> +	 * No need to check rproc->state right away, it will be done in either
> +	 * rproc_detach() or rproc_shutdown().
> +	 */
> +	if (rproc->autonomous_on_core_shutdown)
> +		rproc_detach(rproc);
> +	else
> +		rproc_shutdown(rproc);

same here

>  
>  	mutex_lock(&rproc->lock);
>  	rproc->state = RPROC_DELETED;
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index 02312096d59f..5702f630d810 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -516,6 +516,9 @@ struct rproc_dump_segment {
>   * @nb_vdev: number of vdev currently handled by rproc
>   * @char_dev: character device of the rproc
>   * @cdev_put_on_release: flag to indicate if remoteproc should be shutdown on @char_dev release
> + * @autonomous_on_core_shutdown: true if the remote processor should be detached
> + *				 from (rather than turned off) when the remoteproc
> + *				 core goes away.
>   */
>  struct rproc {
>  	struct list_head node;
> @@ -554,6 +557,7 @@ struct rproc {
>  	u16 elf_machine;
>  	struct cdev cdev;
>  	bool cdev_put_on_release;
> +	bool autonomous_on_core_shutdown;
>  };
>  
>  /**
>