perf tools: Do not check debugfs MAGIC for tracing files

It's rather strange to be checking the debugfs MAGIC number for the
tracing directory. A system admin may want to have a custom set of
events to trace and it should be allowed to let the admin make a temp
file (even for tracing virtual boxes, this is useful).

Also with the coming tracefs, the files may not even be under debugfs,
so checking the debugfs MAGIC number is pointless.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20150202193552.546175764@goodmis.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/api/fs/debugfs.c

@@ -20,6 +20,20 @@ static const char * const debugfs_known_mountpoints[] = {
 
 static bool debugfs_found;
 
+/* verify that a mountpoint is actually a debugfs instance */
+
+static int debugfs_valid_mountpoint(const char *debugfs)
+{
+	struct statfs st_fs;
+
+	if (statfs(debugfs, &st_fs) < 0)
+		return -ENOENT;
+	else if ((long)st_fs.f_type != (long)DEBUGFS_MAGIC)
+		return -ENOENT;
+
+	return 0;
+}
+
 /* find the path to the mounted debugfs */
 const char *debugfs_find_mountpoint(void)
 {
@@ -60,20 +74,6 @@ const char *debugfs_find_mountpoint(void)
 	return debugfs_mountpoint;
 }
 
-/* verify that a mountpoint is actually a debugfs instance */
-
-int debugfs_valid_mountpoint(const char *debugfs)
-{
-	struct statfs st_fs;
-
-	if (statfs(debugfs, &st_fs) < 0)
-		return -ENOENT;
-	else if ((long)st_fs.f_type != (long)DEBUGFS_MAGIC)
-		return -ENOENT;
-
-	return 0;
-}
-
 /* mount the debugfs somewhere if it's not mounted */
 char *debugfs_mount(const char *mountpoint)
 {

tools/lib/api/fs/debugfs.h

@@ -21,7 +21,6 @@
 #endif
 
 const char *debugfs_find_mountpoint(void);
-int debugfs_valid_mountpoint(const char *debugfs);
 char *debugfs_mount(const char *mountpoint);
 
 extern char debugfs_mountpoint[];

tools/perf/util/parse-events.c

@@ -175,9 +175,6 @@ struct tracepoint_path *tracepoint_id_to_path(u64 config)
 	char evt_path[MAXPATHLEN];
 	char dir_path[MAXPATHLEN];
 
-	if (debugfs_valid_mountpoint(tracing_events_path))
-		return NULL;
-
 	sys_dir = opendir(tracing_events_path);
 	if (!sys_dir)
 		return NULL;
@@ -473,12 +470,6 @@ static int add_tracepoint_multi_sys(struct list_head *list, int *idx,
 int parse_events_add_tracepoint(struct list_head *list, int *idx,
 				char *sys, char *event)
 {
-	int ret;
-
-	ret = debugfs_valid_mountpoint(tracing_events_path);
-	if (ret)
-		return ret;
-
 	if (strpbrk(sys, "*?"))
 		return add_tracepoint_multi_sys(list, idx, sys, event);
 	else
@@ -1109,13 +1100,6 @@ void print_tracepoint_events(const char *subsys_glob, const char *event_glob,
 	struct dirent *sys_next, *evt_next, sys_dirent, evt_dirent;
 	char evt_path[MAXPATHLEN];
 	char dir_path[MAXPATHLEN];
-	char sbuf[STRERR_BUFSIZE];
-
-	if (debugfs_valid_mountpoint(tracing_events_path)) {
-		printf("  [ Tracepoints not available: %s ]\n",
-			strerror_r(errno, sbuf, sizeof(sbuf)));
-		return;
-	}
 
 	sys_dir = opendir(tracing_events_path);
 	if (!sys_dir)
@@ -1163,9 +1147,6 @@ int is_valid_tracepoint(const char *event_string)
 	char evt_path[MAXPATHLEN];
 	char dir_path[MAXPATHLEN];
 
-	if (debugfs_valid_mountpoint(tracing_events_path))
-		return 0;
-
 	sys_dir = opendir(tracing_events_path);
 	if (!sys_dir)
 		return 0;