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

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Message-ID: <YElb4PITwZtMhpAw@builder.lan>
Date:   Wed, 10 Mar 2021 17:53:04 -0600
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Mathieu Poirier <mathieu.poirier@...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 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.

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
>