perf tools: Make perf aware of tracefs

As tracefs may be mounted instead of debugfs to get to the event
directories, have perf know about tracefs, and use that file system over
debugfs if it is present.

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/20150202193553.340946602@goodmis.org
[ Fixed up error messages about tracefs pointed out by Namhyung ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 49 insertions, 11 deletions

diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index b86744f29eef..92db3f156b63 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -303,13 +303,26 @@ void set_term_quiet_input(struct termios *old)
         tcsetattr(0, TCSANOW, &tc);
 }
 
-static void set_tracing_events_path(const char *mountpoint)
+static void set_tracing_events_path(const char *tracing, const char *mountpoint)
 {
-        snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s",
-                 mountpoint, "tracing/events");
+        snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s",
+                 mountpoint, tracing, "events");
 }
 
-const char *perf_debugfs_mount(const char *mountpoint)
+static const char *__perf_tracefs_mount(const char *mountpoint)
+{
+        const char *mnt;
+
+        mnt = tracefs_mount(mountpoint);
+        if (!mnt)
+                return NULL;
+
+        set_tracing_events_path("", mnt);
+
+        return mnt;
+}
+
+static const char *__perf_debugfs_mount(const char *mountpoint)
 {
         const char *mnt;
 
@@ -317,7 +330,20 @@ const char *perf_debugfs_mount(const char *mountpoint)
         if (!mnt)
                 return NULL;
 
-        set_tracing_events_path(mnt);
+        set_tracing_events_path("tracing/", mnt);
+
+        return mnt;
+}
+
+const char *perf_debugfs_mount(const char *mountpoint)
+{
+        const char *mnt;
+
+        mnt = __perf_tracefs_mount(mountpoint);
+        if (mnt)
+                return mnt;
+
+        mnt = __perf_debugfs_mount(mountpoint);
 
         return mnt;
 }
@@ -325,12 +351,19 @@ const char *perf_debugfs_mount(const char *mountpoint)
 void perf_debugfs_set_path(const char *mntpt)
 {
         snprintf(debugfs_mountpoint, strlen(debugfs_mountpoint), "%s", mntpt);
-        set_tracing_events_path(mntpt);
+        set_tracing_events_path("tracing/", mntpt);
+}
+
+static const char *find_tracefs(void)
+{
+        const char *path = __perf_tracefs_mount(NULL);
+
+        return path;
 }
 
 static const char *find_debugfs(void)
 {
-        const char *path = perf_debugfs_mount(NULL);
+        const char *path = __perf_debugfs_mount(NULL);
 
         if (!path)
                 fprintf(stderr, "Your kernel does not support the debugfs filesystem");
@@ -344,6 +377,7 @@ static const char *find_debugfs(void)
  */
 const char *find_tracing_dir(void)
 {
+        const char *tracing_dir = "";
         static char *tracing;
         static int tracing_found;
         const char *debugfs;
@@ -351,11 +385,15 @@ const char *find_tracing_dir(void)
         if (tracing_found)
                 return tracing;
 
-        debugfs = find_debugfs();
-        if (!debugfs)
-                return NULL;
+        debugfs = find_tracefs();
+        if (!debugfs) {
+                tracing_dir = "/tracing";
+                debugfs = find_debugfs();
+                if (!debugfs)
+                        return NULL;
+        }
 
-        if (asprintf(&tracing, "%s/tracing", debugfs) < 0)
+        if (asprintf(&tracing, "%s%s", debugfs, tracing_dir) < 0)
                 return NULL;
 
         tracing_found = 1;