linux-kernel - Re: [PATCH v7 12/17] remoteproc: Properly deal with the resource table when stopping

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Message-ID: <20210311171337.GA1113417@xps15>
Date:   Thu, 11 Mar 2021 10:13:37 -0700
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     ohad@...ery.com, arnaud.pouliquen@...com,
        mcoquelin.stm32@...il.com, alexandre.torgue@...com,
        linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v7 12/17] remoteproc: Properly deal with the resource
 table when stopping

On Wed, Mar 10, 2021 at 05:53:04PM -0600, Bjorn Andersson wrote:
> On Wed 10 Mar 15:10 CST 2021, Mathieu Poirier wrote:
> 
> > When a remote processor that was attached to is stopped, special care
> > must be taken to make sure the shutdown process is similar to what
> > it would be had it been started by the remoteproc core.
> > 
> > This patch takes care of that by making a copy of the resource
> > table currently used by the remote processor.  From that point on
> > the copy is used, as if the remote processor had been started by
> > the remoteproc core.
> > 
> > Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
> > ---
> > New for V7:
> >   New Patch, used to be part of 11/16 in V6.
> > ---
> >  drivers/remoteproc/remoteproc_core.c | 53 +++++++++++++++++++++++++++-
> >  1 file changed, 52 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> > index e9ea2558432d..c488b1aa6119 100644
> > --- a/drivers/remoteproc/remoteproc_core.c
> > +++ b/drivers/remoteproc/remoteproc_core.c
> > @@ -1634,6 +1634,52 @@ static int rproc_reset_rsc_table_on_detach(struct rproc *rproc)
> >  	return 0;
> >  }
> >  
> > +static int rproc_reset_rsc_table_on_stop(struct rproc *rproc)
> > +{
> > +	struct resource_table *table_ptr;
> > +
> > +	/* A resource table was never retrieved, nothing to do here */
> > +	if (!rproc->table_ptr)
> > +		return 0;
> > +
> > +	/*
> > +	 * If a cache table exists the remote processor was started by
> > +	 * the remoteproc core.  That cache table should be used for
> > +	 * the rest of the shutdown process.
> > +	 */
> > +	if (rproc->cached_table)
> > +		goto out;
> > +
> > +	/* Remember where the external entity installed the resource table */
> > +	table_ptr = rproc->table_ptr;
> > +
> 
> Afaict this is just a remnant from the detach case.
> 
> I think the series looks really good now, please let me know and I can
> drop the local "table_ptr" as I apply the patches.

(sigh) No matter how long you stare at a patchset there is always one that gets
away.  I will address Arnaud's comment and fix this in a new revision.

Thanks,
Mathieu 

> 
> Regards,
> Bjorn
> 
> > +	/*
> > +	 * If we made it here the remote processor was started by another
> > +	 * entity and a cache table doesn't exist.  As such make a copy of
> > +	 * the resource table currently used by the remote processor and
> > +	 * use that for the rest of the shutdown process.  The memory
> > +	 * allocated here is free'd in rproc_shutdown().
> > +	 */
> > +	rproc->cached_table = kmemdup(rproc->table_ptr,
> > +				      rproc->table_sz, GFP_KERNEL);
> > +	if (!rproc->cached_table)
> > +		return -ENOMEM;
> > +
> > +	/*
> > +	 * Since the remote processor is being switched off the clean table
> > +	 * won't be needed.  Allocated in rproc_set_rsc_table().
> > +	 */
> > +	kfree(rproc->clean_table);
> > +
> > +out:
> > +	/*
> > +	 * Use a copy of the resource table for the remainder of the
> > +	 * shutdown process.
> > +	 */
> > +	rproc->table_ptr = rproc->cached_table;
> > +	return 0;
> > +}
> > +
> >  /*
> >   * Attach to remote processor - similar to rproc_fw_boot() but without
> >   * the steps that deal with the firmware image.
> > @@ -1759,7 +1805,12 @@ static int rproc_stop(struct rproc *rproc, bool crashed)
> >  	rproc_stop_subdevices(rproc, crashed);
> >  
> >  	/* the installed resource table is no longer accessible */
> > -	rproc->table_ptr = rproc->cached_table;
> > +	ret = rproc_reset_rsc_table_on_stop(rproc);
> > +	if (ret) {
> > +		dev_err(dev, "can't reset resource table: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> >  
> >  	/* power off the remote processor */
> >  	ret = rproc->ops->stop(rproc);
> > -- 
> > 2.25.1
> >