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authorDarren Hart <dvhltc@us.ibm.com>2009-10-15 15:30:48 -0700
committerIngo Molnar <mingo@elte.hu>2009-10-16 10:19:18 +0200
commit89061d3d58e1f0742139605dc6a7950aa1ecc019 (patch)
tree4bf78b9d0834975b6e615ced614c74c67d57d52d /kernel
parent237c80c5c8fb7ec128cf2a756b550dc41ad7eac7 (diff)
downloadlinux-89061d3d58e1f0742139605dc6a7950aa1ecc019.tar.gz
futex: Move drop_futex_key_refs out of spinlock'ed region
When requeuing tasks from one futex to another, the reference held by the requeued task to the original futex location needs to be dropped eventually. Dropping the reference may ultimately lead to a call to "iput_final" and subsequently call into filesystem- specific code - which may be non-atomic. It is therefore safer to defer this drop operation until after the futex_hash_bucket spinlock has been dropped. Originally-From: Helge Bahmann <hcb@chaoticmind.net> Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Cc: <stable@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Dinakar Guniguntala <dino@in.ibm.com> Cc: John Stultz <johnstul@linux.vnet.ibm.com> Cc: Sven-Thorsten Dietrich <sdietrich@novell.com> Cc: John Kacur <jkacur@redhat.com> LKML-Reference: <4AD7A298.5040802@us.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/futex.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/futex.c b/kernel/futex.c
index 06938e560ac9..642f3bbaacc7 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1029,7 +1029,6 @@ static inline
void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key,
struct futex_hash_bucket *hb)
{
- drop_futex_key_refs(&q->key);
get_futex_key_refs(key);
q->key = *key;
@@ -1227,6 +1226,7 @@ retry_private:
*/
if (ret == 1) {
WARN_ON(pi_state);
+ drop_count++;
task_count++;
ret = get_futex_value_locked(&curval2, uaddr2);
if (!ret)
@@ -1305,6 +1305,7 @@ retry_private:
if (ret == 1) {
/* We got the lock. */
requeue_pi_wake_futex(this, &key2, hb2);
+ drop_count++;
continue;
} else if (ret) {
/* -EDEADLK */