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

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Message-ID: <20201209213414.GB1814981@xps15>
Date:   Wed, 9 Dec 2020 14:34:14 -0700
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Arnaud POULIQUEN <arnaud.pouliquen@...com>
Cc:     "ohad@...ery.com" <ohad@...ery.com>,
        "bjorn.andersson@...aro.org" <bjorn.andersson@...aro.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "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 Wed, Dec 09, 2020 at 11:13:07AM +0100, Arnaud POULIQUEN wrote:
> 
> 
> 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?

A valid observation...  I'll fix it.

> 
> >  
> >  	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;
> >  };
> >  
> >  /**
> >