Re: [PATCH V4 1/2] tools/perf: Fix the check for parameterized field in event term

[Venkat <venkat88@linux.ibm.com>]

> On 4 May 2026, at 9:12 PM, Athira Rajeev <atrajeev@linux.ibm.com> wrote:
> 
> The format_alias() function in util/pmu.c has a check to
> detect whether the event has parameterized field ( =? ).
> The string alias->terms contains the event and if the event
> has user configurable parameter, there will be presence of
> sub string "=?" in the alias->terms.
> 
> Snippet of code:
> 
> /* Paramemterized events have the parameters shown. */
>       if (strstr(alias->terms, "=?")) {
>               /* No parameters. */
>               snprintf(buf, len, "%.*s/%s/", (int)pmu_name_len, pmu->name, alias->name);
> 
> if "strstr" contains the substring, it returns a pointer
> and hence enters the above check which is not the expected
> check. And hence "perf list" doesn't have the parameterized
> fields in the result.
> 
> Fix this check to use:
> 
> if (!strstr(alias->terms, "=?")) {
> 
> With this change, perf list shows the events correctly with
> the strings showing parameters.
> 
> Before the fix:
> 
> # ./perf list|grep -w PM_PAU_CYC
>  hv_24x7/PM_PAU_CYC/                                [Kernel PMU event]
> 
> With this fix:
> 
> # ./perf list|grep -w PM_PAU_CYC
>  hv_24x7/PM_PAU_CYC,chip=?/                         [Kernel PMU event]
> 
> Signed-off-by: Athira Rajeev <atrajeev@linux.ibm.com>

Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
> ---
> Changelog:
> v3 -> v4:
> Updated commit message to show real example
> addressing review comment from Namhyung.
> 
> v2 -> v3:
> Split the strstr correction in a single patch
> 
> tools/perf/util/pmu.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index 23337d2fa281..0b8d58543f17 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -2117,7 +2117,7 @@ static char *format_alias(char *buf, int len, const struct perf_pmu *pmu,
>   skip_duplicate_pmus);
> 
> /* Paramemterized events have the parameters shown. */
> - if (strstr(alias->terms, "=?")) {
> + if (!strstr(alias->terms, "=?")) {
> /* No parameters. */
> snprintf(buf, len, "%.*s/%s/", (int)pmu_name_len, pmu->name, alias->name);
> return buf;
> -- 
> 2.47.3
>