1 files changed, 42 insertions, 3 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index a15e068535f8..8e02aa690b2b 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -188,6 +188,8 @@ static int ftraced_suspend;
 
 static int ftrace_record_suspend;
 
+static struct dyn_ftrace *ftrace_free_records;
+
 static inline int
 notrace ftrace_ip_in_hash(unsigned long ip, unsigned long key)
 {
@@ -211,8 +213,35 @@ ftrace_add_hash(struct dyn_ftrace *node, unsigned long key)
         hlist_add_head(&node->node, &ftrace_hash[key]);
 }
 
+static notrace void ftrace_free_rec(struct dyn_ftrace *rec)
+{
+        /* no locking, only called from kstop_machine */
+
+        rec->ip = (unsigned long)ftrace_free_records;
+        ftrace_free_records = rec;
+        rec->flags |= FTRACE_FL_FREE;
+}
+
 static notrace struct dyn_ftrace *ftrace_alloc_dyn_node(unsigned long ip)
 {
+        struct dyn_ftrace *rec;
+
+        /* First check for freed records */
+        if (ftrace_free_records) {
+                rec = ftrace_free_records;
+
+                /* todo, disable tracing altogether on this warning */
+                if (unlikely(!(rec->flags & FTRACE_FL_FREE))) {
+                        WARN_ON_ONCE(1);
+                        ftrace_free_records = NULL;
+                        return NULL;
+                }
+
+                ftrace_free_records = (void *)rec->ip;
+                memset(rec, 0, sizeof(*rec));
+                return rec;
+        }
+
         if (ftrace_pages->index == ENTRIES_PER_PAGE) {
                 if (!ftrace_pages->next)
                         return NULL;
@@ -356,8 +385,16 @@ __ftrace_replace_code(struct dyn_ftrace *rec,
         }
 
         failed = ftrace_modify_code(ip, old, new);
-        if (failed)
-                rec->flags |= FTRACE_FL_FAILED;
+        if (failed) {
+                unsigned long key;
+                /* It is possible that the function hasn't been converted yet */
+                key = hash_long(ip, FTRACE_HASHBITS);
+                if (!ftrace_ip_in_hash(ip, key)) {
+                        rec->flags |= FTRACE_FL_FAILED;
+                        ftrace_free_rec(rec);
+                }
+
+        }
 }
 
 static void notrace ftrace_replace_code(int enable)
@@ -407,8 +444,10 @@ ftrace_code_disable(struct dyn_ftrace *rec)
         call = ftrace_call_replace(ip, MCOUNT_ADDR);
 
         failed = ftrace_modify_code(ip, call, nop);
-        if (failed)
+        if (failed) {
                 rec->flags |= FTRACE_FL_FAILED;
+                ftrace_free_rec(rec);
+        }
 }
 
 static int notrace __ftrace_modify_code(void *data)