perf tools: Mount debugfs automatically

Mount debugfs filesystem under '/sys/kernel/debug', if it's not
mounted.

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Clark Williams <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <4B387090.7080407@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 7 insertions, 9 deletions

diff --git a/tools/perf/util/debugfs.c b/tools/perf/util/debugfs.c
index 06b73ee02c49..1f805fde5fd4 100644
--- a/tools/perf/util/debugfs.c
+++ b/tools/perf/util/debugfs.c
@@ -106,16 +106,14 @@ int debugfs_valid_entry(const char *path)
         return 0;
 }
 
-/* mount the debugfs somewhere */
+/* mount the debugfs somewhere if it's not mounted */
 
-int debugfs_mount(const char *mountpoint)
+char *debugfs_mount(const char *mountpoint)
 {
-        char mountcmd[128];
-
         /* see if it's already mounted */
         if (debugfs_find_mountpoint()) {
                 debugfs_premounted = 1;
-                return 0;
+                return debugfs_mountpoint;
         }
 
         /* if not mounted and no argument */
@@ -127,13 +125,13 @@ int debugfs_mount(const char *mountpoint)
                         mountpoint = "/sys/kernel/debug";
         }
 
+        if (mount(NULL, mountpoint, "debugfs", 0, NULL) < 0)
+                return NULL;
+
         /* save the mountpoint */
         strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_mountpoint));
 
-        /* mount it */
-        snprintf(mountcmd, sizeof(mountcmd),
-                 "/bin/mount -t debugfs debugfs %s", mountpoint);
-        return system(mountcmd);
+        return debugfs_mountpoint;
 }
 
 /* umount the debugfs */