Hi all,
Please let me know whether it makes sense to do the following change,
if yes, I will post a formal patch after the merge window, thank you.
-- >8 --
diff --git a/tools/perf/util/print-events.c b/tools/perf/util/print-events.c
index 7b54e9385442..9fa15b32280f 100644
--- a/tools/perf/util/print-events.c
+++ b/tools/perf/util/print-events.c
@@ -67,11 +67,12 @@ 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);
Here are the motivations:
I met "Error: failed to open tracing events directory" twice when execute
"perf list", the first reason is 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 there is no root privileges, so
add the error string to tell the users 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.
(1) Without CONFIG_FTRACE
$ file /sys/kernel/tracing/events
/sys/kernel/tracing/events: cannot open `/sys/kernel/tracing/events'
(No such file or directory)
# file /sys/kernel/tracing/events
/sys/kernel/tracing/events: cannot open `/sys/kernel/tracing/events'
(No such file or directory)
(2) With CONFIG_FTRACE but no root privileges
$ file /sys/kernel/tracing/events
/sys/kernel/tracing/events: cannot open `/sys/kernel/tracing/events'
(Permission denied)
# file /sys/kernel/tracing/events
/sys/kernel/tracing/events: directory
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
At the same time, maybe it needs to do the following tiny change
to avoid duplicate "/" in the file path.
-- >8 --
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;
Before:
/sys/kernel/tracing//events
After:
/sys/kernel/tracing/events
Thanks,
Tiezhu