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Subject[PATCH 2/6] futex: add futex_q static initializer
Date
The futex_q struct has grown considerably over the last year or so. I
believe it now merits a static initializer to avoid uninitialized data
errors (having just spent more time than I care to admit debugging
an uninitialized q.bitset in an experimental new op code).

I originally planned on following the __THING_INITIALIZER/DECLARE_THING
method, but since we already had FUTEX_KEY_INIT, and I personally prefer
that method, I went that route.

Signed-off-by: Darren Hart <dvhltc@us.ibm.com>
---
kernel/futex.c | 19 +++++++++----------
1 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index ed08cfd..2ae18cd 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -130,6 +130,12 @@ struct futex_q {
u32 bitset;
};

+#define FUTEX_Q_INIT \
+ { /* list gets initialized in queue_me()*/ \
+ .task = NULL, NULL, FUTEX_KEY_INIT \
+ , NULL, NULL, NULL, 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
@@ -1799,16 +1805,13 @@ static int futex_wait(u32 __user *uaddr, int flags, u32 val, ktime_t *abs_time,
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;
@@ -1899,7 +1902,7 @@ static int futex_lock_pi(u32 __user *uaddr, 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())
@@ -1913,9 +1916,6 @@ static int futex_lock_pi(u32 __user *uaddr, 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);
@@ -2206,7 +2206,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, int flags,
struct rt_mutex *pi_mutex = NULL;
struct futex_hash_bucket *hb;
union futex_key key2;
- struct futex_q q;
+ struct futex_q q = FUTEX_Q_INIT;
int res, ret;

if (!bitset)
@@ -2234,7 +2234,6 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, int flags,
if (unlikely(ret != 0))
goto out;

- q.pi_state = NULL;
q.bitset = bitset;
q.rt_waiter = &rt_waiter;
q.requeue_pi_key = &key2;
--
1.6.3.3


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