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Commit de87fcc1 authored by Darren Hart's avatar Darren Hart Committed by Ingo Molnar
Browse files

futex: additional (get|put)_futex_key() fixes 



Impact: fix races

futex_requeue and futex_lock_pi still had some bad
(get|put)_futex_key() usage. This patch adds the missing
put_futex_keys() and corrects a goto in futex_lock_pi() to avoid
a double get.

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: <20090312075545.9856.75152.stgit@Aeon>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent b2d0994b

kernel/futex.c

+11 −5
Original line number Diff line number Diff line
@@ -802,8 +802,10 @@ retry: 


		ret = get_user(dummy, uaddr2);

		if (ret)

			return ret;

			goto out_put_keys;



		put_futex_key(fshared, &key2);

		put_futex_key(fshared, &key1);

		goto retryfull;

	}
@@ -878,6 +880,9 @@ retry: 
			if (hb1 != hb2)

				spin_unlock(&hb2->lock);



			put_futex_key(fshared, &key2);

			put_futex_key(fshared, &key1);



			ret = get_user(curval, uaddr1);



			if (!ret)
@@ -1453,6 +1458,7 @@ retry_locked: 
			 * exit to complete.

			 */

			queue_unlock(&q, hb);

			put_futex_key(fshared, &q.key);

			cond_resched();

			goto retry;
@@ -1595,13 +1601,12 @@ uaddr_faulted: 


	ret = get_user(uval, uaddr);

	if (!ret)

		goto retry;

		goto retry_unlocked;



	if (to)

		destroy_hrtimer_on_stack(&to->timer);

	return ret;

	goto out_put_key;

}





/*

 * Userspace attempted a TID -> 0 atomic transition, and failed.

 * This is the in-kernel slowpath: we look up the PI state (if any),
@@ -1705,6 +1710,7 @@ pi_faulted: 
	}



	ret = get_user(uval, uaddr);

	put_futex_key(fshared, &key);

	if (!ret)

		goto retry;