linux-kernel - Re: [v3 2/5] coresight: refactor with function of_coresight_get

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Message-ID: <75112177-e5c1-0532-04b1-842a985b077d@arm.com>
Date:   Thu, 9 Mar 2017 15:28:31 +0000
From:   Suzuki K Poulose <Suzuki.Poulose@....com>
To:     leo.yan@...aro.org
Cc:     linux-arm-kernel@...ts.infradead.org,
        Wei Xu <xuwei5@...ilicon.com>, catalin.marinas@....com,
        will.deacon@....com, mark.rutland@....com,
        mathieu.poirier@...aro.org, Stephen Boyd <sboyd@...eaurora.org>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        mike.leach@...aro.org, Michael Turquette <mturquette@...libre.com>,
        Guodong Xu <guodong.xu@...aro.org>,
        John Stultz <john.stultz@...aro.org>
Subject: Re: [v3 2/5] coresight: refactor with function of_coresight_get_cpu

On 09/03/17 11:01, Suzuki K Poulose wrote:
> On 03/03/17 06:00, Leo Yan wrote:
>> This is refactor to add function of_coresight_get_cpu(), so it's used to
>> retrieve CPU id for coresight component. Finally can use it as a common
>> function for multiple places.
>>
>> Suggested-by: Mathieu Poirier <mathieu.poirier@...aro.org>
>> Signed-off-by: Leo Yan <leo.yan@...aro.org>
>> ---
>>  drivers/hwtracing/coresight/of_coresight.c | 37 ++++++++++++++++++++----------
>>  include/linux/coresight.h                  |  2 ++
>>  2 files changed, 27 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/of_coresight.c b/drivers/hwtracing/coresight/of_coresight.c
>> index 629e031..d9a12fb 100644
>> --- a/drivers/hwtracing/coresight/of_coresight.c
>> +++ b/drivers/hwtracing/coresight/of_coresight.c
>> @@ -101,14 +101,36 @@ static int of_coresight_alloc_memory(struct device *dev,
>>  	return 0;
>>  }
>>
>> +int of_coresight_get_cpu(struct device_node *node)
>> +{
>> +	int cpu;
>> +	struct device_node *dn;
>> +
>> +	dn = of_parse_phandle(node, "cpu", 0);
>> +
>> +	/* Affinity defaults to CPU0 */
>> +	if (!dn)
>> +		return 0;
>> +
>> +	for_each_possible_cpu(cpu) {
>> +		if (dn == of_get_cpu_node(cpu, NULL)) {
>
> We should do of_node_put() on the node returned by of_get_cpu_node,
> and I accept that this was there before the refactoring. We could do
> something like :
>
>
> ----8>------
>
>
>
> [PATCH] coresight: of_coresight_get_cpu: Add missing of_node_put
>
> The of_coresight_get_cpu iterates over the possible CPU nodes
> to find a given cpu phandle. However it does not drop the reference
> to the node pointer returned by the of_get_cpu_node.
>
> Cc: Leo Yan <leo.yan@...aro.org>
> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
> ---
>  drivers/hwtracing/coresight/of_coresight.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/of_coresight.c b/drivers/hwtracing/coresight/of_coresight.c
> index d9a12fb..8c6f4a0 100644
> --- a/drivers/hwtracing/coresight/of_coresight.c
> +++ b/drivers/hwtracing/coresight/of_coresight.c
> @@ -104,7 +104,8 @@ static int of_coresight_alloc_memory(struct device *dev,
>  int of_coresight_get_cpu(struct device_node *node)
>  {
>  	int cpu;
> -	struct device_node *dn;
> +	bool found;
> +	struct device_node *dn, *np;
>
>  	dn = of_parse_phandle(node, "cpu", 0);
>
> @@ -113,15 +114,16 @@ int of_coresight_get_cpu(struct device_node *node)
>  		return 0;
>
>  	for_each_possible_cpu(cpu) {
> -		if (dn == of_get_cpu_node(cpu, NULL)) {
> -			of_node_put(dn);
> -			return cpu;
> -		}
> +		np = of_get_cpu_node(cpu, NULL);
> +		found = (dn == np);
> +		of_node_put(np);
> +		if (found)
> +			break;
>  	}
>
> -	/* Affinity to CPU0 if no cpu nodes are found */
>  	of_node_put(dn);
> -	return 0;
> +	/* Affinity to CPU0 if no cpu nodes are found */
> +	return cpu_possible(cpu) ? cpu : 0;

This could be even :
	return found ? cpu : 0;

Suzuki