Re: [PATCH v7 11/17] remoteproc: Properly deal with the resource table when detaching

[Arnaud POULIQUEN <arnaud.pouliquen@foss.st.com>]

Hi Mathieu,

Just a minor comment, with that
Reviewed-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>


On 3/10/21 10:10 PM, Mathieu Poirier wrote:
> If it is possible to detach the remote processor, keep an untouched
> copy of the resource table.  That way we can start from the same
> resource table without having to worry about original values or what
> elements the startup code has changed when re-attaching to the remote
> processor.
> 
> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> ---
> New for V7:
>   New Patch, used to be part of 11/16 in V6.
> ---
>  drivers/remoteproc/remoteproc_core.c | 77 ++++++++++++++++++++++++++++
>  include/linux/remoteproc.h           |  3 ++
>  2 files changed, 80 insertions(+)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 5eaa47c3ba92..e9ea2558432d 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -1556,6 +1556,24 @@ static int rproc_set_rsc_table(struct rproc *rproc)
>  		return ret;
>  	}
>  
> +	/*
> +	 * If it is possible to detach the remote processor, keep an untouched
> +	 * copy of the resource table.  That way we can start fresh again when
> +	 * the remote processor is re-attached, that is:
> +	 *
> +	 *      DETACHED -> ATTACHED -> DETACHED -> ATTACHED
> +	 *
> +	 * Free'd in rproc_reset_rsc_table_on_detach() and
> +	 * rproc_reset_rsc_table_on_stop().
> +	 */
> +	if (rproc->ops->detach) {
> +		rproc->clean_table = kmemdup(table_ptr, table_sz, GFP_KERNEL);
> +		if (!rproc->clean_table)
> +			return -ENOMEM;
> +	} else {
> +		rproc->clean_table = NULL;
> +	}
> +
>  	rproc->cached_table = NULL;
>  	rproc->table_ptr = table_ptr;
>  	rproc->table_sz = table_sz;
> @@ -1563,6 +1581,59 @@ static int rproc_set_rsc_table(struct rproc *rproc)
>  	return 0;
>  }
>  
> +static int rproc_reset_rsc_table_on_detach(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 we made it to this point a clean_table _must_ have been
> +	 * allocated in rproc_set_rsc_table().  If one isn't present
> +	 * something went really wrong and we must complain.
> +	 */
> +	if (WARN_ON(!rproc->clean_table))
> +		return -EINVAL;
> +
> +	/* Remember where the external entity installed the resource table */
> +	table_ptr = rproc->table_ptr;
> +
> +	/*
> +	 * 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_detach().
> +	 */
> +	rproc->cached_table = kmemdup(rproc->table_ptr,
> +				      rproc->table_sz, GFP_KERNEL);
> +	if (!rproc->cached_table)
> +		return -ENOMEM;
> +
> +	/*
> +	 * Use a copy of the resource table for the remainder of the
> +	 * shutdown process.
> +	 */
> +	rproc->table_ptr = rproc->cached_table;
> +
> +	/*
> +	 * Reset the memory area where the firmware loaded the resource table
> +	 * to its original value.  That way when we re-attach the remote
> +	 * processor the resource table is clean and ready to be used again.
> +	 */
> +	memcpy(table_ptr, rproc->clean_table, rproc->table_sz);
> +
> +	/*
> +	 * The clean resource table is no longer needed.  Allocated in
> +	 * rproc_set_rsc_table().
> +	 */
> +	kfree(rproc->clean_table);
> +
> +	return 0;
> +}
> +
>  /*
>   * Attach to remote processor - similar to rproc_fw_boot() but without
>   * the steps that deal with the firmware image.
> @@ -1721,6 +1792,9 @@ static int __rproc_detach(struct rproc *rproc)
>  	/* Stop any subdevices for the remote processor */
>  	rproc_stop_subdevices(rproc, false);
>  
> +	/* the installed resource table is no longer accessible */
> +	ret = rproc_reset_rsc_table_on_detach(rproc);
> +

Something seems missing here to treat the error case.

Regards,

Arnaud

>  	/* Tell the remote processor the core isn't available anymore */
>  	ret = rproc->ops->detach(rproc);
>  	if (ret) {
> @@ -1997,6 +2071,9 @@ int rproc_detach(struct rproc *rproc)
>  
>  	rproc_disable_iommu(rproc);
>  
> +	/* Free the copy of the resource table */
> +	kfree(rproc->cached_table);
> +	rproc->cached_table = NULL;
>  	rproc->table_ptr = NULL;
>  out:
>  	mutex_unlock(&rproc->lock);
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index e1c843c19cc6..e5f52a12a650 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -514,6 +514,8 @@ struct rproc_dump_segment {
>   * @recovery_disabled: flag that state if recovery was disabled
>   * @max_notifyid: largest allocated notify id.
>   * @table_ptr: pointer to the resource table in effect
> + * @clean_table: copy of the resource table without modifications.  Used
> + *		 when a remote processor is attached or detached from the core
>   * @cached_table: copy of the resource table
>   * @table_sz: size of @cached_table
>   * @has_iommu: flag to indicate if remote processor is behind an MMU
> @@ -550,6 +552,7 @@ struct rproc {
>  	bool recovery_disabled;
>  	int max_notifyid;
>  	struct resource_table *table_ptr;
> +	struct resource_table *clean_table;
>  	struct resource_table *cached_table;
>  	size_t table_sz;
>  	bool has_iommu;
>