trace-cmd: Mount debugfs if it is not mounted

If debugfs is not mounted, then mount it for the user. When debugfs
is configured in the kernel the directory /sys/kernel/debug should
exist. Mount it there and make Greg KH happy.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 24 insertions, 2 deletions

diff --git a/trace-util.c b/trace-util.c
index 7d168f9..d6c1948 100644
--- a/trace-util.c
+++ b/trace-util.c
@@ -6,12 +6,14 @@
 #include <ctype.h>
 #include <errno.h>
 #include <dlfcn.h>
+#include <sys/mount.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 
 #include "trace-cmd.h"
 
 #define PLUGIN_DIR ".trace-cmd/plugins"
+#define DEBUGFS_PATH "/sys/kernel/debug"
 
 #define __weak __attribute__((weak))
 
@@ -197,6 +199,22 @@ load_plugin(struct pevent *pevent, struct plugin_list *plugin_list,
         return plugin_list;
 }
 
+static int mount_debugfs(void)
+{
+        struct stat st;
+        int ret;
+
+        /* make sure debugfs exists */
+        ret = stat(DEBUGFS_PATH, &st);
+        if (ret < 0)
+                die("debugfs is not configured on this kernel");
+
+        ret = mount("nodev", DEBUGFS_PATH,
+                    "debugfs", 0, NULL);
+
+        return ret;
+}
+
 char *tracecmd_find_tracing_dir(void)
 {
         char debugfs[MAX_PATH+1];
@@ -219,8 +237,12 @@ char *tracecmd_find_tracing_dir(void)
         fclose(fp);
 
         if (strcmp(type, "debugfs") != 0) {
-                warning("debugfs not mounted, please mount");
-                return NULL;
+                /* If debugfs is not mounted, try to mount it */
+                if (mount_debugfs() < 0) {
+                        warning("debugfs not mounted, please mount");
+                        return NULL;
+                }
+                strcpy(debugfs, DEBUGFS_PATH);
         }
 
         tracing_dir = malloc_or_die(strlen(debugfs) + 9);