linux-kernel - Re: [PATCH v2 2/2] perf tools: Fix pattern matching for same substring in different pmu type

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Message-ID: <62c7f221-64af-f6b2-147c-09d56667ccd6@linux.intel.com>
Date:   Wed, 30 Jun 2021 15:18:14 -0400
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     Jin Yao <yao.jin@...ux.intel.com>, acme@...nel.org,
        jolsa@...nel.org, peterz@...radead.org, mingo@...hat.com,
        alexander.shishkin@...ux.intel.com
Cc:     Linux-kernel@...r.kernel.org, ak@...ux.intel.com,
        kan.liang@...el.com, yao.jin@...el.com
Subject: Re: [PATCH v2 2/2] perf tools: Fix pattern matching for same
 substring in different pmu type



On 6/30/2021 8:09 AM, Jin Yao wrote:
> Some different pmu types may have same substring. For example,
> on Icelake server, we have pmu types "uncore_imc" and
> "uncore_imc_free_running". Both pmu types have substring "uncore_imc".
> But the parser would wrongly think they are the same pmu type.
> 
> We enable an imc event,
> perf stat -e uncore_imc/event=0xe3/ -a -- sleep 1
> 
> Perf actually expands the event to:
> uncore_imc_0/event=0xe3/
> uncore_imc_1/event=0xe3/
> uncore_imc_2/event=0xe3/
> uncore_imc_3/event=0xe3/
> uncore_imc_4/event=0xe3/
> uncore_imc_5/event=0xe3/
> uncore_imc_6/event=0xe3/
> uncore_imc_7/event=0xe3/
> uncore_imc_free_running_0/event=0xe3/
> uncore_imc_free_running_1/event=0xe3/
> uncore_imc_free_running_3/event=0xe3/
> uncore_imc_free_running_4/event=0xe3/
> 
> That's because the "uncore_imc_free_running" matches the
> pattern "uncore_imc*".
> 
> Now we check that the last characters of pmu name is
> '_<digit>'.
> 
> For pattern "uncore_imc*", "uncore_imc_0" is parsed ok,
> but "uncore_imc_free_running_0" is failed.
> 
> Fixes: b2b9d3a3f021 ("perf pmu: Support wildcards on pmu name in dynamic pmu events")
> Signed-off-by: Jin Yao <yao.jin@...ux.intel.com>
> ---
>   tools/perf/util/pmu.c | 28 +++++++++++++++++++++++++++-
>   1 file changed, 27 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index 96f5ff9b5440..9ee123d77e6d 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -3,6 +3,7 @@
>   #include <linux/compiler.h>
>   #include <linux/string.h>
>   #include <linux/zalloc.h>
> +#include <linux/ctype.h>
>   #include <subcmd/pager.h>
>   #include <sys/types.h>
>   #include <errno.h>
> @@ -741,6 +742,28 @@ struct pmu_events_map *__weak pmu_events_map__find(void)
>   	return perf_pmu__find_map(NULL);
>   }
>   
> +static bool perf_pmu__valid_suffix(char *tok, char *pmu_name)
> +{
> +	char *p;
> +
> +	/*
> +	 * The pmu_name has substring tok. If the format of

The uncore PMU may have two names, e.g., uncore_cha_Y or 
uncore_type_X_Y. User can use either name. I don't think we can assume 
that the pmu_name has substring tok. I think we should add a check as below.


@@ -746,6 +746,8 @@ static bool perf_pmu__valid_suffix(char *tok, char 
*pmu_name)
  {
  	char *p;

+	if (strncmp(pmu_name, tok, strlen(tok)))
+		return false;
	/*
	 * The pmu_name has substring tok. If the format of
  	 * pmu_name is tok or tok_digit, return true.

> +	 * pmu_name is tok or tok_digit, return true.
> +	 */
> +	p = pmu_name + strlen(tok);
> +	if (*p == 0)
> +		return true;
> +
> +	if (*p != '_')
> +		return false;
> +
> +	++p;
> +	if (*p == 0 || !isdigit(*p))
> +		return false;
> +
> +	return true;
> +}
> +
>   bool pmu_uncore_alias_match(const char *pmu_name, const char *name)
>   {
>   	char *tmp = NULL, *tok, *str;
> @@ -769,7 +792,7 @@ bool pmu_uncore_alias_match(const char *pmu_name, const char *name)
>   	 */
>   	for (; tok; name += strlen(tok), tok = strtok_r(NULL, ",", &tmp)) {
>   		name = strstr(name, tok);
> -		if (!name) {
> +		if (!name || !perf_pmu__valid_suffix(tok, (char *)name)) {
>   			res = false;
>   			goto out;
>   		}
> @@ -1886,5 +1909,8 @@ int perf_pmu__pattern_match(struct perf_pmu *pmu, char *pattern, char *tok)
>   	if (fnmatch(pattern, name, 0))
>   		return -1;
>   
> +	if (!perf_pmu__valid_suffix(tok, name))
> +		return -1;
> +

They are still two functions. I'm wondering if we can merge the two 
functions to one function, e.g., perf_pmu_match()?

So my patch just need to simply do
  	if (!perf_pmu_match(tok, name) && !perf_pmu_match(tok, 
pmu->alias_name)) 		return -1;

Thanks,
Kan