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Subject: Re: [PATCH v4 1/2] perf pmu: Add PMU alias support
To:     Jin Yao <yao.jin@linux.intel.com>, <acme@kernel.org>,
        <jolsa@kernel.org>, <peterz@infradead.org>, <mingo@redhat.com>,
        <alexander.shishkin@linux.intel.com>
CC:     <Linux-kernel@vger.kernel.org>, <linux-perf-users@vger.kernel.org>,
        <ak@linux.intel.com>, <kan.liang@intel.com>, <yao.jin@intel.com>,
        <rickyman7@gmail.com>, Kan Liang <kan.liang@linux.intel.com>
References: <20210811024827.9483-1-yao.jin@linux.intel.com>
 <20210811024827.9483-2-yao.jin@linux.intel.com>
From:   John Garry <john.garry@huawei.com>
Message-ID: <8730872e-dae1-4d95-48aa-60b15dec2fa7@huawei.com>
Date:   Thu, 12 Aug 2021 13:14:53 +0100
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perf pmu: Add x86 PMU alias support

> +char *pmu_find_real_name(const char *name)
> +{
> +	static bool cached_list;
> +
> +	if (cached_list)
> +		return __pmu_find_real_name(name);
> +
> +	setup_pmu_alias_list();
> +	cached_list = true;
> +
> +	return __pmu_find_real_name(name);
> +}
> +
> +char *pmu_find_alias_name(const char *name)
> +{
> +	struct perf_pmu_alias_name *pmu;
> +
> +	list_for_each_entry(pmu, &pmu_alias_name_list, list) {
> +		if (!strcmp(name, pmu->name))
> +			return strdup(pmu->alias);

I would not expect a function which does a "find" to duplicate the name.

Same goes for all the other places which does similar.

> +	}
> +	return NULL;
> +}
> diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
> index 9321bd0e2f76..d94e48e1ff9b 100644
> --- a/tools/perf/util/parse-events.y
> +++ b/tools/perf/util/parse-events.y
> @@ -316,7 +316,8 @@ event_pmu_name opt_pmu_config
>   			if (!strncmp(name, "uncore_", 7) &&
>   			    strncmp($1, "uncore_", 7))
>   				name += 7;
> -			if (!perf_pmu__match(pattern, name, $1)) {
> +			if (!perf_pmu__match(pattern, name, $1) ||
> +			    !perf_pmu__match(pattern, pmu->alias_name, $1)) {
>   				if (parse_events_copy_term_list(orig_terms, &terms))
>   					CLEANUP_YYABORT;
>   				if (!parse_events_add_pmu(_parse_state, list, pmu->name, terms, true, false))
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index fc683bc41715..796a4be752f4 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -946,6 +946,18 @@ perf_pmu__get_default_config(struct perf_pmu *pmu __maybe_unused)
>   	return NULL;
>   }
>   
> +char * __weak
> +pmu_find_real_name(const char *name)
> +{
> +	return strdup(name);
> +}

That's not finding anything.

> +
> +char * __weak
> +pmu_find_alias_name(const char *name __maybe_unused)
> +{
> +	return NULL;
 > +}
> +
>   static int pmu_max_precise(const char *name)
>   {
>   	char path[PATH_MAX];
> @@ -959,19 +971,25 @@ static int pmu_max_precise(const char *name)
>   	return max_precise;
>   }
>   
> -static struct perf_pmu *pmu_lookup(const char *name)
> +static struct perf_pmu *pmu_lookup(const char *lookup_name)
>   {
> -	struct perf_pmu *pmu;
> +	struct perf_pmu *pmu = NULL;
>   	LIST_HEAD(format);
>   	LIST_HEAD(aliases);
>   	__u32 type;
> -	bool is_hybrid = perf_pmu__hybrid_mounted(name);
> +	bool is_hybrid;
> +	char *name = pmu_find_real_name(lookup_name);
> +
> +	if (!name)
> +		return NULL;
> +
> +	is_hybrid = perf_pmu__hybrid_mounted(name);
>   
>   	/*
>   	 * Check pmu name for hybrid and the pmu may be invalid in sysfs
>   	 */
>   	if (!strncmp(name, "cpu_", 4) && !is_hybrid)
> -		return NULL;
> +		goto out;
>   
>   	/*
>   	 * The pmu data we store & need consists of the pmu
> @@ -979,23 +997,24 @@ static struct perf_pmu *pmu_lookup(const char *name)
>   	 * now.
>   	 */
>   	if (pmu_format(name, &format))
> -		return NULL;
> +		goto out;
>   
>   	/*
>   	 * Check the type first to avoid unnecessary work.
>   	 */
>   	if (pmu_type(name, &type))
> -		return NULL;
> +		goto out;
>   
>   	if (pmu_aliases(name, &aliases))
> -		return NULL;
> +		goto out;
>   
>   	pmu = zalloc(sizeof(*pmu));
>   	if (!pmu)
> -		return NULL;
> +		goto out;
>   
>   	pmu->cpus = pmu_cpumask(name);
> -	pmu->name = strdup(name);
> +	pmu->name = name;
> +	pmu->alias_name = pmu_find_alias_name(name);
>   	pmu->type = type;
>   	pmu->is_uncore = pmu_is_uncore(name);
>   	if (pmu->is_uncore)
> @@ -1017,6 +1036,10 @@ static struct perf_pmu *pmu_lookup(const char *name)
>   
>   	pmu->default_config = perf_pmu__get_default_config(pmu);
>   
> +out:
> +	if (!pmu)
> +		free(name);

I don't understand this. There are lots of places this function can fail 
, but we don't free memories allocated previously - why just free this one?

> +
>   	return pmu;
>   }
>   
> @@ -1025,7 +1048,8 @@ static struct perf_pmu *pmu_find(const char *name)
>   	struct perf_pmu *pmu;
>   
>   	list_for_each_entry(pmu, &pmus, list)
> -		if (!strcmp(pmu->name, name))
> +		if (!strcmp(pmu->name, name) ||
> +		    (pmu->alias_name && !strcmp(pmu->alias_name, name)))
>   			return pmu;

I'd be inclined to use {} for the list_for_each_entry() call

>   
>   	return NULL;
> @@ -1920,6 +1944,9 @@ bool perf_pmu__has_hybrid(void)
>   
>   int perf_pmu__match(char *pattern, char *name, char *tok)
>   {
> +	if (!name)
> +		return -1;
> +
>   	if (fnmatch(pattern, name, 0))
>   		return -1;
>   
> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
> index 926da483a141..f6ca9f6a06ef 100644
> --- a/tools/perf/util/pmu.h
> +++ b/tools/perf/util/pmu.h
> @@ -21,6 +21,7 @@ enum {
>   #define PERF_PMU_FORMAT_BITS 64
>   #define EVENT_SOURCE_DEVICE_PATH "/bus/event_source/devices/"
>   #define CPUS_TEMPLATE_CPU	"%s/bus/event_source/devices/%s/cpus"
> +#define MAX_PMU_NAME_LEN 128
>   
>   struct perf_event_attr;
>   
> @@ -32,6 +33,7 @@ struct perf_pmu_caps {
>   
>   struct perf_pmu {
>   	char *name;
> +	char *alias_name;	/* PMU alias name */

useless comment

>   	char *id;
>   	__u32 type;
>   	bool selectable;
> @@ -135,4 +137,7 @@ void perf_pmu__warn_invalid_config(struct perf_pmu *pmu, __u64 config,
>   bool perf_pmu__has_hybrid(void);
>   int perf_pmu__match(char *pattern, char *name, char *tok);
>   
> +char *pmu_find_real_name(const char *name);
> +char *pmu_find_alias_name(const char *name);
> +
>   #endif /* __PMU_H */
>