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Subject[PATCH] futex: add WARN_ON to catch certain assymetric (get|put)_futex_key calls
Date
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: "Peter Zijlstra" <peterz@infradead.org>
Cc: "Thomas Gleixner" <tglx@linutronix.de>
Cc: "Rusty Russell" <rusty@au1.ibm.com>
---

kernel/futex.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index 748778a..5288acf 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(1);
return;
+ }

switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) {
case FUT_OFF_INODE:


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