ftrace: fix updating of ftrace_update_cnt

Hi Ingo/Steven,

Ftrace currently maintains an update count which includes false updates,
i.e, updates which failed. If anything, such failures should be tracked
by some separate variable, but this patch provides a minimal fix.

Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Cc: rostedt@goodmis.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 5 insertions, 3 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 9b7c54f8a62f..1843edc098a6 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -453,7 +453,7 @@ static void ftrace_shutdown_replenish(void)
         ftrace_pages->next = (void *)get_zeroed_page(GFP_KERNEL);
 }
 
-static void
+static int
 ftrace_code_disable(struct dyn_ftrace *rec)
 {
         unsigned long ip;
@@ -469,7 +469,9 @@ ftrace_code_disable(struct dyn_ftrace *rec)
         if (failed) {
                 rec->flags |= FTRACE_FL_FAILED;
                 ftrace_free_rec(rec);
+                return 0;
         }
+        return 1;
 }
 
 static int __ftrace_modify_code(void *data)
@@ -617,8 +619,8 @@ static int __ftrace_update_code(void *ignore)
 
                 /* all CPUS are stopped, we are safe to modify code */
                 hlist_for_each_entry(p, t, &head, node) {
-                        ftrace_code_disable(p);
-                        ftrace_update_cnt++;
+                        if (ftrace_code_disable(p))
+                                ftrace_update_cnt++;
                 }
 
         }