ftrace: Enable trampoline when rec count returns back to one

[linux-2.6-microblaze.git] / kernel / trace / ftrace.c

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 4f2c26b..5c3eadb 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1622,6 +1622,11 @@ static bool test_rec_ops_needs_regs(struct dyn_ftrace *rec)
        return  keep_regs;
 }
 
+static struct ftrace_ops *
+ftrace_find_tramp_ops_any(struct dyn_ftrace *rec);
+static struct ftrace_ops *
+ftrace_find_tramp_ops_next(struct dyn_ftrace *rec, struct ftrace_ops *ops);
+
 static bool __ftrace_hash_rec_update(struct ftrace_ops *ops,
                                     int filter_hash,
                                     bool inc)
@@ -1750,15 +1755,17 @@ static bool __ftrace_hash_rec_update(struct ftrace_ops *ops,
                        }
 
                        /*
-                        * If the rec had TRAMP enabled, then it needs to
-                        * be cleared. As TRAMP can only be enabled iff
-                        * there is only a single ops attached to it.
-                        * In otherwords, always disable it on decrementing.
-                        * In the future, we may set it if rec count is
-                        * decremented to one, and the ops that is left
-                        * has a trampoline.
+                        * The TRAMP needs to be set only if rec count
+                        * is decremented to one, and the ops that is
+                        * left has a trampoline. As TRAMP can only be
+                        * enabled if there is only a single ops attached
+                        * to it.
                         */
-                       rec->flags &= ~FTRACE_FL_TRAMP;
+                       if (ftrace_rec_count(rec) == 1 &&
+                           ftrace_find_tramp_ops_any(rec))
+                               rec->flags |= FTRACE_FL_TRAMP;
+                       else
+                               rec->flags &= ~FTRACE_FL_TRAMP;
 
                        /*
                         * flags will be cleared in ftrace_check_record()
@@ -1951,11 +1958,6 @@ static void print_ip_ins(const char *fmt, const unsigned char *p)
                printk(KERN_CONT "%s%02x", i ? ":" : "", p[i]);
 }
 
-static struct ftrace_ops *
-ftrace_find_tramp_ops_any(struct dyn_ftrace *rec);
-static struct ftrace_ops *
-ftrace_find_tramp_ops_next(struct dyn_ftrace *rec, struct ftrace_ops *ops);
-
 enum ftrace_bug_type ftrace_bug_type;
 const void *ftrace_expected;