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>

1 files changed, 11 insertions, 22 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 3ded796e10e0..8323082dbc21 100644
--- 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;
 }
 
 /*