linux-kernel - Re: [PATCH V2 2/3] tools/perf: Use is_perf_pid_map_name helper function to check dso's of pattern /tmp/perf-%d.map

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Date: Mon, 17 Jun 2024 22:23:59 +0530
From: Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
To: James Clark <james.clark@....com>,
        Chaitanya S Prakash <chaitanyas.prakash@....com>
Cc: LKML <linux-kernel@...r.kernel.org>,
        linux-perf-users <linux-perf-users@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>, akanksha@...ux.ibm.com,
        Madhavan Srinivasan <maddy@...ux.ibm.com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        Disha Goel <disgoel@...ux.vnet.ibm.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>, Adrian Hunter <adrian.hunter@...el.com>,
        Ian Rogers <irogers@...gle.com>, namhyung@...nel.org
Subject: Re: [PATCH V2 2/3] tools/perf: Use is_perf_pid_map_name helper
 function to check dso's of pattern /tmp/perf-%d.map



> On 17 Jun 2024, at 7:29 PM, James Clark <james.clark@....com> wrote:
> 
> 
> 
> On 17/06/2024 14:03, Athira Rajeev wrote:
>> commit 80d496be89ed ("perf report: Add support for profiling JIT
>> generated code") added support for profiling JIT generated code.
>> This patch handles dso's of form "/tmp/perf-$PID.map".
>> 
>> Some of the references doesn't check exactly for same pattern.
>> some uses "if (!strncmp(dso_name, "/tmp/perf-", 10))". Fix
>> this by using helper function is_perf_pid_map_name which looks
>> for proper pattern of form: "/tmp/perf-$PID.map" for these checks.
>> 
>> Signed-off-by: Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
>> ---
>> tools/perf/util/dsos.c    | 2 +-
>> tools/perf/util/srcline.c | 2 +-
>> 2 files changed, 2 insertions(+), 2 deletions(-)
>> 
>> diff --git a/tools/perf/util/dsos.c b/tools/perf/util/dsos.c
>> index ab3d0c01dd63..23cd02aa701d 100644
>> --- a/tools/perf/util/dsos.c
>> +++ b/tools/perf/util/dsos.c
>> @@ -275,7 +275,7 @@ static void dso__set_basename(struct dso *dso)
>> char *base, *lname;
>> int tid;
>> 
>> - if (sscanf(dso__long_name(dso), "/tmp/perf-%d.map", &tid) == 1) {
>> + if (is_perf_pid_map_name(dso__long_name(dso))) {
>> if (asprintf(&base, "[JIT] tid %d", tid) < 0)
>> return;
>> } else {
>> diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
>> index 9d670d8c1c08..51eb78993fe2 100644
>> --- a/tools/perf/util/srcline.c
>> +++ b/tools/perf/util/srcline.c
>> @@ -39,7 +39,7 @@ static const char *srcline_dso_name(struct dso *dso)
>> if (dso_name[0] == '[')
>> return NULL;
>> 
>> - if (!strncmp(dso_name, "/tmp/perf-", 10))
>> + if (is_perf_pid_map_name(dso_name))
>> return NULL;
>> 
>> return dso_name;
> 
> Duplicate of [1] but the latest version of the other one looks like it
> might have a mistake in it.
> 
> For this one I get this compilation error:
> 
> util/dsos.c: In function ‘dso__set_basename’:
> util/dsos.c:279:21: error: ‘tid’ may be used uninitialized
> [-Werror=maybe-uninitialized]
>  279 |                 if (asprintf(&base, "[JIT] tid %d", tid) < 0)
> 

Hi James,

Thanks for pointing this. I had my first version here: https://lore.kernel.org/linux-perf-users/5d9a9842-9b8a-428c-898f-e1ff866a6e66@intel.com/T/#m5fbfa712a411c0e09b8177d31fc1c2d12f437fa5 which used regex for matching the dso name in util/symbol.c

Got suggestion from Adrian to use “sscanf” and have a helper function since this /tmp/perf-%d.map check is done in other places as well ( in util/dsos.c, util/srcline.c ). This V2 address those changes. I didn’t hit the compile error, but that is a valid one which you reported since “tid” needs to be taken care of. I will check this compile error

Thanks
Athira 
> 
> 
> [1]:
> https://lore.kernel.org/linux-perf-users/20240601125946.1741414-10-ChaitanyaS.Prakash@arm.com/