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Commit 5eb3dc62 authored by Darren Hart's avatar Darren Hart Committed by Ingo Molnar
Browse files

futex: add double_unlock_hb() 



Impact: cleanup

The futex code uses double_lock_hb() which locks the hb->lock's
in pointer value order.  There is no parallel unlock routine,
and the code unlocks them in name order, ignoring pointer value.

This patch adds double_unlock_hb() to refactor the duplicated
code segments.

Build and boot tested on a 4 way Intel x86_64 workstation.
Passes basic pthread_mutex and PI tests out of
ltp/testcases/realtime.

Signed-off-by: default avatarDarren Hart <dvhltc@us.ibm.com>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
LKML-Reference: <20090312075552.9856.48021.stgit@Aeon>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent de87fcc1

kernel/futex.c

+17 −12
Original line number Diff line number Diff line
@@ -690,6 +690,19 @@ double_lock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) 
	}

}



static inline void

double_unlock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2)

{

	if (hb1 <= hb2) {

		spin_unlock(&hb2->lock);

		if (hb1 < hb2)

			spin_unlock(&hb1->lock);

	} else { /* hb1 > hb2 */

		spin_unlock(&hb1->lock);

		spin_unlock(&hb2->lock);

	}

}



/*

 * Wake up waiters matching bitset queued on this futex (uaddr).

 */
@@ -767,9 +780,7 @@ retry: 
	if (unlikely(op_ret < 0)) {

		u32 dummy;



		spin_unlock(&hb1->lock);

		if (hb1 != hb2)

			spin_unlock(&hb2->lock);

		double_unlock_hb(hb1, hb2);



#ifndef CONFIG_MMU

		/*
@@ -833,9 +844,7 @@ retry: 
		ret += op_ret;

	}



	spin_unlock(&hb1->lock);

	if (hb1 != hb2)

		spin_unlock(&hb2->lock);

	double_unlock_hb(hb1, hb2);

out_put_keys:

	put_futex_key(fshared, &key2);

out_put_key1:
@@ -876,9 +885,7 @@ retry: 
		ret = get_futex_value_locked(&curval, uaddr1);



		if (unlikely(ret)) {

			spin_unlock(&hb1->lock);

			if (hb1 != hb2)

				spin_unlock(&hb2->lock);

			double_unlock_hb(hb1, hb2);



			put_futex_key(fshared, &key2);

			put_futex_key(fshared, &key1);
@@ -925,9 +932,7 @@ retry: 
	}



out_unlock:

	spin_unlock(&hb1->lock);

	if (hb1 != hb2)

		spin_unlock(&hb2->lock);

	double_unlock_hb(hb1, hb2);



	/* drop_futex_key_refs() must be called outside the spinlocks. */

	while (--drop_count >= 0)