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

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Date:   Thu, 11 Mar 2021 10:14:23 +0100
From:   Arnaud POULIQUEN <arnaud.pouliquen@...s.st.com>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        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 3/11/21 12:53 AM, 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.
> 

Just a minor comment on patch 11, then the series LGTM also,

For this one
Reviewed-by: Arnaud Pouliquen <arnaud.pouliquen@...com>

Thanks,
Arnaud

> 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
>>