linux-kernel - Re: [PATCH 6/9] perf record: Support synthesizing cgroup events

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Date:   Thu, 9 Jan 2020 16:50:24 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Mark Rutland <mark.rutland@....com>,
        Stephane Eranian <eranian@...gle.com>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-perf-users <linux-perf-users@...r.kernel.org>
Subject: Re: [PATCH 6/9] perf record: Support synthesizing cgroup events

On Thu, Jan 9, 2020 at 7:18 AM Jiri Olsa <jolsa@...hat.com> wrote:
>
> On Tue, Jan 07, 2020 at 10:34:58PM +0900, Namhyung Kim wrote:
>
> SNIP
>
> > +     if (perf_tool__process_synth_event(tool, event, machine, process) < 0) {
> > +             pr_debug("process synth event failed\n");
> > +             return -1;
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static int perf_event__walk_cgroup_tree(struct perf_tool *tool,
> > +                                     union perf_event *event,
> > +                                     char *path, size_t mount_len,
> > +                                     perf_event__handler_t process,
> > +                                     struct machine *machine)
> > +{
> > +     size_t pos = strlen(path);
> > +     DIR *d;
> > +     struct dirent *dent;
> > +     int ret = 0;
> > +
> > +     if (perf_event__synthesize_cgroup(tool, event, path, mount_len,
> > +                                       process, machine) < 0)
> > +             return -1;
> > +
> > +     d = opendir(path);
> > +     if (d == NULL) {
> > +             pr_debug("failed to open directory: %s\n", path);
> > +             return -1;
> > +     }
> > +
> > +     while ((dent = readdir(d)) != NULL) {
> > +             if (dent->d_type != DT_DIR)
> > +                     continue;
> > +             if (!strcmp(dent->d_name, ".") ||
> > +                 !strcmp(dent->d_name, ".."))
> > +                     continue;
> > +
> > +             if (path[pos - 1] != '/')
> > +                     strcat(path, "/");
> > +             strcat(path, dent->d_name);
>
> shouldn't you also check for the max size of path in here?

I guess a path should be shorter than PATH_MAX.
But yes, I can add a check if you want.

Thanks
Namhyung