From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Ian Rogers <irogers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Namhyung Kim <namhyung@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>,
Adrian Hunter <adrian.hunter@intel.com>,
Kan Liang <kan.liang@linux.intel.com>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] perf tracepoint: Don't scan all tracepoints to test if one exists
Date: Thu, 9 May 2024 18:43:00 -0300 [thread overview]
Message-ID: <Zj1DZMB3fzVMPyzE@x1> (raw)
In-Reply-To: <20240509153245.1990426-1-irogers@google.com>
On Thu, May 09, 2024 at 08:32:45AM -0700, Ian Rogers wrote:
> In is_valid_tracepoint, rather than scanning
> "/sys/kernel/tracing/events/*/*" skipping any path where
> "/sys/kernel/tracing/events/*/*/id" doesn't exist, and then testing if
> "*:*" matches the tracepoint name, just use the given tracepoint name
> replace the ':' with '/' and see if the id file exists. This turns a
> nested directory search into a single file available test.
>
> Rather than return 1 for valid and 0 for invalid, return true and
> false.
>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> v2. Fix potential uninitialized use on memory allocation failure path.
Thanks, applied to perf-tools-next,
- Arnaldo
> ---
> tools/perf/util/tracepoint.c | 56 ++++++++++++++----------------------
> tools/perf/util/tracepoint.h | 3 +-
> 2 files changed, 24 insertions(+), 35 deletions(-)
>
> diff --git a/tools/perf/util/tracepoint.c b/tools/perf/util/tracepoint.c
> index 92dd8b455b90..bb06d10fbe37 100644
> --- a/tools/perf/util/tracepoint.c
> +++ b/tools/perf/util/tracepoint.c
> @@ -4,10 +4,12 @@
> #include <errno.h>
> #include <fcntl.h>
> #include <stdio.h>
> +#include <stdlib.h>
> #include <sys/param.h>
> #include <unistd.h>
>
> #include <api/fs/tracing_path.h>
> +#include "fncache.h"
>
> int tp_event_has_id(const char *dir_path, struct dirent *evt_dir)
> {
> @@ -26,39 +28,25 @@ int tp_event_has_id(const char *dir_path, struct dirent *evt_dir)
> /*
> * Check whether event is in <debugfs_mount_point>/tracing/events
> */
> -int is_valid_tracepoint(const char *event_string)
> +bool is_valid_tracepoint(const char *event_string)
> {
> - DIR *sys_dir, *evt_dir;
> - struct dirent *sys_dirent, *evt_dirent;
> - char evt_path[MAXPATHLEN];
> - char *dir_path;
> -
> - sys_dir = tracing_events__opendir();
> - if (!sys_dir)
> - return 0;
> -
> - for_each_subsystem(sys_dir, sys_dirent) {
> - dir_path = get_events_file(sys_dirent->d_name);
> - if (!dir_path)
> - continue;
> - evt_dir = opendir(dir_path);
> - if (!evt_dir)
> - goto next;
> -
> - for_each_event(dir_path, evt_dir, evt_dirent) {
> - snprintf(evt_path, MAXPATHLEN, "%s:%s",
> - sys_dirent->d_name, evt_dirent->d_name);
> - if (!strcmp(evt_path, event_string)) {
> - closedir(evt_dir);
> - put_events_file(dir_path);
> - closedir(sys_dir);
> - return 1;
> - }
> - }
> - closedir(evt_dir);
> -next:
> - put_events_file(dir_path);
> - }
> - closedir(sys_dir);
> - return 0;
> + char *dst, *path = malloc(strlen(event_string) + 4); /* Space for "/id\0". */
> + const char *src;
> + bool have_file = false; /* Conservatively return false if memory allocation failed. */
> +
> + if (!path)
> + return false;
> +
> + /* Copy event_string replacing the ':' with '/'. */
> + for (src = event_string, dst = path; *src; src++, dst++)
> + *dst = (*src == ':') ? '/' : *src;
> + /* Add "/id\0". */
> + memcpy(dst, "/id", 4);
> +
> + dst = get_events_file(path);
> + if (dst)
> + have_file = file_available(dst);
> + free(dst);
> + free(path);
> + return have_file;
> }
> diff --git a/tools/perf/util/tracepoint.h b/tools/perf/util/tracepoint.h
> index c4a110fe87d7..65ccb01fc312 100644
> --- a/tools/perf/util/tracepoint.h
> +++ b/tools/perf/util/tracepoint.h
> @@ -4,6 +4,7 @@
>
> #include <dirent.h>
> #include <string.h>
> +#include <stdbool.h>
>
> int tp_event_has_id(const char *dir_path, struct dirent *evt_dir);
>
> @@ -20,6 +21,6 @@ int tp_event_has_id(const char *dir_path, struct dirent *evt_dir);
> (strcmp(sys_dirent->d_name, ".")) && \
> (strcmp(sys_dirent->d_name, "..")))
>
> -int is_valid_tracepoint(const char *event_string);
> +bool is_valid_tracepoint(const char *event_string);
>
> #endif /* __PERF_TRACEPOINT_H */
> --
> 2.45.0.rc1.225.g2a3ae87e7f-goog
prev parent reply other threads:[~2024-05-09 21:43 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-09 15:32 [PATCH v2] perf tracepoint: Don't scan all tracepoints to test if one exists Ian Rogers
2024-05-09 21:43 ` Arnaldo Carvalho de Melo [this message]
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