Commit 5bdb05f9 authored by Darren Hart's avatar Darren Hart Committed by Thomas Gleixner
Browse files

futex: Add futex_q static initializer 



The futex_q struct has grown considerably over the last couple years. I
believe it now merits a static initializer to avoid uninitialized data
errors (having spent more time than I care to admit debugging an uninitialized
q.bitset in an experimental new op code).

With the key initializer built in, several of the FUTEX_KEY_INIT calls can
be removed.

V2: use a static variable instead of an init macro.
    use a C99 initializer and don't rely on variable ordering in the struct.
V3: make futex_q_init const

Signed-off-by: default avatarDarren Hart <dvhart@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <1289252428-18383-1-git-send-email-dvhart@linux.intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent b41277dc

kernel/futex.c

+10 −15
Original line number Diff line number Diff line
@@ -131,6 +131,12 @@ struct futex_q { 
	u32 bitset;

};



static const struct futex_q futex_q_init = {

	/* list gets initialized in queue_me()*/

	.key = FUTEX_KEY_INIT,

	.bitset = FUTEX_BITSET_MATCH_ANY

};



/*

 * Hash buckets are shared by all the futex_keys that hash to the same

 * location.  Each key may have multiple futex_q structures, one for each task
@@ -1750,7 +1756,6 @@ static int futex_wait_setup(u32 __user *uaddr, u32 val, unsigned int flags, 
	 * rare, but normal.

	 */

retry:

	q->key = FUTEX_KEY_INIT;

	ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &q->key);

	if (unlikely(ret != 0))

		return ret;
@@ -1791,16 +1796,12 @@ static int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val, 
	struct hrtimer_sleeper timeout, *to = NULL;

	struct restart_block *restart;

	struct futex_hash_bucket *hb;

	struct futex_q q;

	struct futex_q q = futex_q_init;

	int ret;



	if (!bitset)

		return -EINVAL;



	q.pi_state = NULL;

	q.bitset = bitset;

	q.rt_waiter = NULL;

	q.requeue_pi_key = NULL;



	if (abs_time) {

		to = &timeout;
@@ -1891,7 +1892,7 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags, int detect, 
{

	struct hrtimer_sleeper timeout, *to = NULL;

	struct futex_hash_bucket *hb;

	struct futex_q q;

	struct futex_q q = futex_q_init;

	int res, ret;



	if (refill_pi_state_cache())
@@ -1905,11 +1906,7 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags, int detect, 
		hrtimer_set_expires(&to->timer, *time);

	}



	q.pi_state = NULL;

	q.rt_waiter = NULL;

	q.requeue_pi_key = NULL;

retry:

	q.key = FUTEX_KEY_INIT;

	ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &q.key);

	if (unlikely(ret != 0))

		goto out;
@@ -2197,8 +2194,8 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags, 
	struct rt_mutex_waiter rt_waiter;

	struct rt_mutex *pi_mutex = NULL;

	struct futex_hash_bucket *hb;

	union futex_key key2;

	struct futex_q q;

	union futex_key key2 = FUTEX_KEY_INIT;

	struct futex_q q = futex_q_init;

	int res, ret;



	if (!bitset)
@@ -2221,12 +2218,10 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags, 
	debug_rt_mutex_init_waiter(&rt_waiter);

	rt_waiter.task = NULL;



	key2 = FUTEX_KEY_INIT;

	ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2);

	if (unlikely(ret != 0))

		goto out;



	q.pi_state = NULL;

	q.bitset = bitset;

	q.rt_waiter = &rt_waiter;

	q.requeue_pi_key = &key2;

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