Commit-ID: cd84a42f315e50edd454c27a3da3951ccd3d735a Gitweb: http://git.kernel.org/tip/cd84a42f315e50edd454c27a3da3951ccd3d735a Author: Darren Hart <dvhltc@xxxxxxxxxx> AuthorDate: Thu, 2 Apr 2009 14:19:38 -0700 Committer: Ingo Molnar <mingo@xxxxxxx> CommitDate: Thu, 2 Apr 2009 23:39:53 +0200 futex: comment requeue key reference semantics 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: Nick Piggin <nickpiggin@xxxxxxxxxxxx> Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- kernel/futex.c | 7 ++++++- 1 files changed, 6 insertions(+), 1 deletions(-) diff --git a/kernel/futex.c b/kernel/futex.c index 6b50a02..eef8cd2 100644 --- a/kernel/futex.c +++ b/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); -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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