[PATCH v2] perf parse-events: Don't report unreadable tracepoint globs as unknown

[Hang Zhengyang via B4 Relay <devnull+hang.zhengyang1010.gmail.com@kernel.org>]

From: Hang Zhengyang <hang.zhengyang1010@gmail.com>

As a normal user, a tracepoint glob gets the wrong error:

  $ perf stat -e 'syscalls:*' true
  event syntax error: 'syscalls:*'
                       \___ unknown tracepoint

  Error:  File /sys/kernel/tracing//events/syscalls/* not found.
  Hint:   Perhaps this kernel misses some CONFIG_ setting to enable this feature?.

add_tracepoint_multi_sys() returns ENOENT when nothing matched and
drops the error from reading the directories.  Return that error
instead, so the glob reports what a plain tracepoint name does:

  $ perf stat -e 'syscalls:*' true
  event syntax error: 'syscalls:*'
                       \___ can't access trace events

  Error:  No permissions to read /sys/kernel/tracing//events/syscalls/*
  Hint:   Try 'sudo mount -o remount,mode=755 /sys/kernel/tracing/'

Fixes: d002aab87de8 ("perf tp_pmu: Factor existing tracepoint logic to new file")
Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Hang Zhengyang <hang.zhengyang1010@gmail.com>
---
Thanks for the review, Ian.
---
Changes in v2:
- Show the output after the fix (Ian)
- Link to v1: https://lore.kernel.org/r/20261110-tp-glob-errno-v1-1-6c2cb609c590@gmail.com
---
 tools/perf/util/parse-events.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index f3ba70d4f76b..8a6d5a13863d 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -572,8 +572,10 @@ static int add_tracepoint_multi_sys(struct parse_events_state *parse_state,
 		ret = tp_pmu__for_each_tp_sys(&args, add_tracepoint_multi_sys_cb);
 	}
 	if (args.found == 0) {
-		tracepoint_error(err, ENOENT, sys_glob, evt_glob, loc->first_column);
-		return -ENOENT;
+		if (!ret)
+			ret = -ENOENT;
+		tracepoint_error(err, ret, sys_glob, evt_glob, loc->first_column);
+		return ret;
 	}
 	return ret;
 }

---
base-commit: 13a8d580433a3b72b10be34f0e26787fe5659d3c
change-id: 20261110-tp-glob-errno-672ea1eb786b

Best regards,
-- 
Hang Zhengyang <hang.zhengyang1010@gmail.com>