The patch titled
futex: comment requeue key reference semantics
has been removed from the -mm tree. Its filename was
futex-comment-requeue-key-reference-semantics.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: futex: comment requeue key reference semantics
From: Darren Hart <dvhltc@xxxxxxxxxx>
We've tripped over the futex_requeue drop_count refering to key2
instead of key1. The code is actually correct, but is non-intuitive.
This patch adds an explicit comment explaining the requeue.
Signed-off-by: Darren Hart <dvhltc@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/futex.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff -puN kernel/futex.c~futex-comment-requeue-key-reference-semantics kernel/futex.c
--- a/kernel/futex.c~futex-comment-requeue-key-reference-semantics
+++ a/kernel/futex.c
@@ -883,7 +883,12 @@ retry_private:
out_unlock:
double_unlock_hb(hb1, hb2);
- /* drop_futex_key_refs() must be called outside the spinlocks. */
+ /*
+ * drop_futex_key_refs() must be called outside the spinlocks. During
+ * the requeue we moved futex_q's from the hash bucket at key1 to the
+ * one at key2 and updated their key pointer. We no longer need to
+ * hold the references to key1.
+ */
while (--drop_count >= 0)
drop_futex_key_refs(&key1);
_
Patches currently in -mm which might be from dvhltc@xxxxxxxxxx are
linux-next.patch
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