ftrace: Simplify ftrace_hash_disable/enable path in ftrace_hash_move

Simplify ftrace_hash_disable/enable path in ftrace_hash_move
for hardening the process if the memory allocation failed.

Link: http://lkml.kernel.org/p/20140617110442.15167.81076.stgit@kbuild-fedora.novalocal
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 3ded796e10e05beeb4c3504af9be48cbf8cae563..8323082dbc21955c2773827478ba37d027234cc9 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1306,25 +1306,15 @@ ftrace_hash_move(struct ftrace_ops *ops, int enable,
        struct ftrace_hash *new_hash;
        int size = src->count;
        int bits = 0;
-       int ret;
        int i;
 
-       /*
-        * Remove the current set, update the hash and add
-        * them back.
-        */
-       ftrace_hash_rec_disable(ops, enable);
-
        /*
         * If the new source is empty, just free dst and assign it
         * the empty_hash.
         */
        if (!src->count) {
-               free_ftrace_hash_rcu(*dst);
-               rcu_assign_pointer(*dst, EMPTY_HASH);
-               /* still need to update the function records */
-               ret = 0;
-               goto out;
+               new_hash = EMPTY_HASH;
+               goto update;
        }
 
        /*
@@ -1337,10 +1327,9 @@ ftrace_hash_move(struct ftrace_ops *ops, int enable,
        if (bits > FTRACE_HASH_MAX_BITS)
                bits = FTRACE_HASH_MAX_BITS;
 
-       ret = -ENOMEM;
        new_hash = alloc_ftrace_hash(bits);
        if (!new_hash)
-               goto out;
+               return -ENOMEM;
 
        size = 1 << src->size_bits;
        for (i = 0; i < size; i++) {
@@ -1351,20 +1340,20 @@ ftrace_hash_move(struct ftrace_ops *ops, int enable,
                }
        }
 
+update:
+       /*
+        * Remove the current set, update the hash and add
+        * them back.
+        */
+       ftrace_hash_rec_disable(ops, enable);
+
        old_hash = *dst;
        rcu_assign_pointer(*dst, new_hash);
        free_ftrace_hash_rcu(old_hash);
 
-       ret = 0;
- out:
-       /*
-        * Enable regardless of ret:
-        *  On success, we enable the new hash.
-        *  On failure, we re-enable the original hash.
-        */
        ftrace_hash_rec_enable(ops, enable);
 
-       return ret;
+       return 0;
 }
 
 /*