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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: Darren 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: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Darren Hart 2010-11-08 13:40:28 -08:00 committed by Thomas Gleixner
parent b41277dc7a
commit 5bdb05f91b
1 changed files with 10 additions and 15 deletions
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25
kernel/futex.c
View File

@ -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;