[PATCH 0/2] Small changes for perf tools

[PATCH 0/2] Small changes for perf tools

[Tiezhu Yang]

Tiezhu Yang (2):
  perf tools: Fix wrong message when running "make JOBS=1"
  perf list: Give clues if failed to open tracing events directory

 tools/lib/api/fs/tracing_path.c | 2 +-
 tools/perf/Makefile             | 8 +++++++-
 tools/perf/util/print-events.c  | 3 ++-
 3 files changed, 10 insertions(+), 3 deletions(-)

-- 
2.42.0

[PATCH 1/2] perf tools: Fix wrong message when running "make JOBS=1"

[Tiezhu Yang]

There is only one job when running "make JOBS=1", it should
print "sequential build" rather than "parallel build".

Before:

$ cd tools/perf && make JOBS=1
  BUILD:   Doing 'make -j1' parallel build

After:

$ cd tools/perf && make JOBS=1
  BUILD:   Doing 'make -j1' sequential build

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 tools/perf/Makefile | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index 75f3f6e0a231..816d5d84816b 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -51,8 +51,14 @@ else
   override DEBUG = 0
 endif
 
+ifeq ($(JOBS),1)
+  BUILD_TYPE := sequential
+else
+  BUILD_TYPE := parallel
+endif
+
 define print_msg
-  @printf '  BUILD:   Doing '\''make \033[33m-j'$(JOBS)'\033[m'\'' parallel build\n'
+  @printf '  BUILD:   Doing '\''make \033[33m-j'$(JOBS)'\033[m'\'' $(BUILD_TYPE) build\n'
 endef
 
 define make
-- 
2.42.0

[PATCH 2/2] perf list: Give clues if failed to open tracing events directory

[Tiezhu Yang]

When executing the command "perf list", I met "Error: failed to open
tracing events directory" twice, the first reason is that there is no
"/sys/kernel/tracing/events" directory due to it does not enable the
kernel tracing infrastructure with CONFIG_FTRACE, the second reason
is that there is no root privileges.

Add the error string to tell the users what happened and what should
to do, and also call put_tracing_file() to free events_path a little
later to avoid messy code in the error message.

At the same time, just remove the redundant "/" of the file path in
the function get_tracing_file(), otherwise it shows something like
"/sys/kernel/tracing//events".

Before:

  $ ./perf list
  Error: failed to open tracing events directory

After:

(1) Without CONFIG_FTRACE

  $ ./perf list
  Error: failed to open tracing events directory
  /sys/kernel/tracing/events: No such file or directory

(2) With CONFIG_FTRACE but no root privileges

  $ ./perf list
  Error: failed to open tracing events directory
  /sys/kernel/tracing/events: Permission denied

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 tools/lib/api/fs/tracing_path.c | 2 +-
 tools/perf/util/print-events.c  | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/lib/api/fs/tracing_path.c b/tools/lib/api/fs/tracing_path.c
index 30745f35d0d2..834fd64c7130 100644
--- a/tools/lib/api/fs/tracing_path.c
+++ b/tools/lib/api/fs/tracing_path.c
@@ -69,7 +69,7 @@ char *get_tracing_file(const char *name)
 {
 	char *file;
 
-	if (asprintf(&file, "%s/%s", tracing_path_mount(), name) < 0)
+	if (asprintf(&file, "%s%s", tracing_path_mount(), name) < 0)
 		return NULL;
 
 	return file;
diff --git a/tools/perf/util/print-events.c b/tools/perf/util/print-events.c
index 3f38c27f0157..81e0135cddf0 100644
--- a/tools/perf/util/print-events.c
+++ b/tools/perf/util/print-events.c
@@ -68,11 +68,12 @@ void print_tracepoint_events(const struct print_callbacks *print_cb __maybe_unus
 	struct dirent **sys_namelist = NULL;
 	int sys_items;
 
-	put_tracing_file(events_path);
 	if (events_fd < 0) {
 		pr_err("Error: failed to open tracing events directory\n");
+		pr_err("%s: %s\n", events_path, strerror(errno));
 		return;
 	}
+	put_tracing_file(events_path);
 
 	sys_items = tracing_events__scandir_alphasort(&sys_namelist);
 
-- 
2.42.0

Re: [PATCH 0/2] Small changes for perf tools

[Arnaldo Carvalho de Melo]

On Tue, Jul 30, 2024 at 02:22:59PM +0800, Tiezhu Yang wrote:
> Tiezhu Yang (2):
>   perf tools: Fix wrong message when running "make JOBS=1"
>   perf list: Give clues if failed to open tracing events directory

Thanks, tested and applied.

- Arnaldo
 
>  tools/lib/api/fs/tracing_path.c | 2 +-
>  tools/perf/Makefile             | 8 +++++++-
>  tools/perf/util/print-events.c  | 3 ++-
>  3 files changed, 10 insertions(+), 3 deletions(-)
> 
> -- 
> 2.42.0