From 90621c40cc4ab7b0a414311ce37e7cc7173403b6 Mon Sep 17 00:00:00 2001
From: Darren Hart <dvhltc@us.ibm.com>
Date: Mon, 29 Dec 2008 19:43:21 -0800
Subject: [PATCH] futex: catch certain assymetric (get|put)_futex_key calls
Impact: add debug check
Following up on my previous key reference accounting patches, this patch
will catch puts on keys that haven't been "got". This won't catch nested
get/put mismatches though.
Build and boot tested, with minimal desktop activity and a run of the
open_posix_testsuite in LTP for testing. No warnings logged.
Signed-off-by: Darren Hart <dvhltc@us.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/futex.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel/futex.c b/kernel/futex.c
index c5ac55cc0c1603..206d4c906885c8 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -170,8 +170,11 @@ static void get_futex_key_refs(union futex_key *key)
*/
static void drop_futex_key_refs(union futex_key *key)
{
- if (!key->both.ptr)
+ if (!key->both.ptr) {
+ /* If we're here then we tried to put a key we failed to get */
+ WARN_ON_ONCE(1);
return;
+ }
switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) {
case FUT_OFF_INODE:
--
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