[tip:perf/core] perf list: Show error if tracepoints not available

[tip-bot for Pekka Enberg]

Commit-ID:  f11cfc6f294dbd83b0d58037404df2bd16066238
Gitweb:     http://git.kernel.org/tip/f11cfc6f294dbd83b0d58037404df2bd16066238
Author:     Pekka Enberg <penberg@xxxxxxxxxx>
AuthorDate: Tue, 15 Oct 2013 23:07:27 +0300
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Mon, 21 Oct 2013 17:33:22 -0300

perf list: Show error if tracepoints not available

Tracepoints are not visible in "perf list" on Fedora 19 because regular
users have no permission to /sys/kernel/debug by default. Show an error
message so that the user knows about it instead of assuming that
tracepoints are not supported on the system.

Signed-off-by: Pekka Enberg <penberg@xxxxxxxxxx>
Acked-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1381867647-8594-1-git-send-email-penberg@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/parse-events.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 9812531..c90e55c 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -998,8 +998,10 @@ void print_tracepoint_events(const char *subsys_glob, const char *event_glob,
 	char evt_path[MAXPATHLEN];
 	char dir_path[MAXPATHLEN];
 
-	if (debugfs_valid_mountpoint(tracing_events_path))
+	if (debugfs_valid_mountpoint(tracing_events_path)) {
+		printf("  [ Tracepoints not available: %s ]\n", strerror(errno));
 		return;
+	}
 
 	sys_dir = opendir(tracing_events_path);
 	if (!sys_dir)
--
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