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authorDarren Hart <dvhltc@us.ibm.com>2008-12-29 19:43:21 -0800
committerIngo Molnar <mingo@elte.hu>2009-01-02 23:10:44 +0100
commit90621c40cc4ab7b0a414311ce37e7cc7173403b6 (patch)
tree3f5797462898f3f85bad1a31df04e671df8aadd3 /kernel/futex.c
parent42d35d48ce7cefb9429880af19d1c329d1554e7a (diff)
downloadlinux-90621c40cc4ab7b0a414311ce37e7cc7173403b6.tar.gz
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>
Diffstat (limited to 'kernel/futex.c')
-rw-r--r--kernel/futex.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/futex.c b/kernel/futex.c
index c5ac55cc0c16..206d4c906885 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: