[for-next][PATCH 07/21] ftrace: Simplify ftrace_hash_disable/enable path in ftrace_hash_move

Steven Rostedt
2014-07-03T16:12:29Z

[-- Attachment #1: 0007-ftrace-Simplify-ftrace_hash_disable-enable-path-in-f.patch --]
[-- Type: text/plain, Size: 2132 bytes --]

From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

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>
---
kernel/trace/ftrace.c | 33 +++++++++++----------------------
1 file 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;
}

/*
--
2.0.0