FUTEX: Tidy up the code
The recent PRIVATE and REQUEUE_PI changes to the futex code made it hard to
read. Tidy it up.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/futex.c b/kernel/futex.c
index 45490be..5c3f45d 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -121,6 +121,24 @@
static struct vfsmount *futex_mnt;
/*
+ * Take mm->mmap_sem, when futex is shared
+ */
+static inline void futex_lock_mm(struct rw_semaphore *fshared)
+{
+ if (fshared)
+ down_read(fshared);
+}
+
+/*
+ * Release mm->mmap_sem, when the futex is shared
+ */
+static inline void futex_unlock_mm(struct rw_semaphore *fshared)
+{
+ if (fshared)
+ up_read(fshared);
+}
+
+/*
* We hash on the keys returned from get_futex_key (see below).
*/
static struct futex_hash_bucket *hash_futex(union futex_key *key)
@@ -287,7 +305,18 @@
}
EXPORT_SYMBOL_GPL(drop_futex_key_refs);
-static inline int get_futex_value_locked(u32 *dest, u32 __user *from)
+static u32 cmpxchg_futex_value_locked(u32 __user *uaddr, u32 uval, u32 newval)
+{
+ u32 curval;
+
+ pagefault_disable();
+ curval = futex_atomic_cmpxchg_inatomic(uaddr, uval, newval);
+ pagefault_enable();
+
+ return curval;
+}
+
+static int get_futex_value_locked(u32 *dest, u32 __user *from)
{
int ret;
@@ -620,9 +649,7 @@
newval = FUTEX_WAITERS | new_owner->pid;
- pagefault_disable();
- curval = futex_atomic_cmpxchg_inatomic(uaddr, uval, newval);
- pagefault_enable();
+ curval = cmpxchg_futex_value_locked(uaddr, uval, newval);
if (curval == -EFAULT)
ret = -EFAULT;
@@ -659,9 +686,7 @@
* There is no waiter, so we unlock the futex. The owner died
* bit has not to be preserved here. We are the owner:
*/
- pagefault_disable();
- oldval = futex_atomic_cmpxchg_inatomic(uaddr, uval, 0);
- pagefault_enable();
+ oldval = cmpxchg_futex_value_locked(uaddr, uval, 0);
if (oldval == -EFAULT)
return oldval;
@@ -700,8 +725,7 @@
union futex_key key;
int ret;
- if (fshared)
- down_read(fshared);
+ futex_lock_mm(fshared);
ret = get_futex_key(uaddr, fshared, &key);
if (unlikely(ret != 0))
@@ -725,8 +749,7 @@
spin_unlock(&hb->lock);
out:
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
return ret;
}
@@ -746,8 +769,7 @@
int ret, op_ret, attempt = 0;
retryfull:
- if (fshared)
- down_read(fshared);
+ futex_lock_mm(fshared);
ret = get_futex_key(uaddr1, fshared, &key1);
if (unlikely(ret != 0))
@@ -793,7 +815,7 @@
*/
if (attempt++) {
ret = futex_handle_fault((unsigned long)uaddr2,
- fshared, attempt);
+ fshared, attempt);
if (ret)
goto out;
goto retry;
@@ -803,8 +825,7 @@
* If we would have faulted, release mmap_sem,
* fault it in and start all over again.
*/
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
ret = get_user(dummy, uaddr2);
if (ret)
@@ -841,8 +862,8 @@
if (hb1 != hb2)
spin_unlock(&hb2->lock);
out:
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
+
return ret;
}
@@ -861,8 +882,7 @@
int ret, drop_count = 0;
retry:
- if (fshared)
- down_read(fshared);
+ futex_lock_mm(fshared);
ret = get_futex_key(uaddr1, fshared, &key1);
if (unlikely(ret != 0))
@@ -890,8 +910,7 @@
* If we would have faulted, release mmap_sem, fault
* it in and start all over again.
*/
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
ret = get_user(curval, uaddr1);
@@ -944,8 +963,7 @@
drop_futex_key_refs(&key1);
out:
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
return ret;
}
@@ -1113,10 +1131,7 @@
while (!ret) {
newval = (uval & FUTEX_OWNER_DIED) | newtid;
- pagefault_disable();
- curval = futex_atomic_cmpxchg_inatomic(uaddr,
- uval, newval);
- pagefault_enable();
+ curval = cmpxchg_futex_value_locked(uaddr, uval, newval);
if (curval == -EFAULT)
ret = -EFAULT;
@@ -1134,6 +1149,7 @@
#define ARG3_SHARED 1
static long futex_wait_restart(struct restart_block *restart);
+
static int futex_wait(u32 __user *uaddr, struct rw_semaphore *fshared,
u32 val, ktime_t *abs_time)
{
@@ -1148,8 +1164,7 @@
q.pi_state = NULL;
retry:
- if (fshared)
- down_read(fshared);
+ futex_lock_mm(fshared);
ret = get_futex_key(uaddr, fshared, &q.key);
if (unlikely(ret != 0))
@@ -1186,8 +1201,7 @@
* If we would have faulted, release mmap_sem, fault it in and
* start all over again.
*/
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
ret = get_user(uval, uaddr);
@@ -1206,8 +1220,7 @@
* Now the futex is queued and we have checked the data, we
* don't want to hold mmap_sem while we sleep.
*/
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
/*
* There might have been scheduling since the queue_me(), as we
@@ -1285,8 +1298,7 @@
queue_unlock(&q, hb);
out_release_sem:
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
return ret;
}
@@ -1333,8 +1345,7 @@
q.pi_state = NULL;
retry:
- if (fshared)
- down_read(fshared);
+ futex_lock_mm(fshared);
ret = get_futex_key(uaddr, fshared, &q.key);
if (unlikely(ret != 0))
@@ -1353,9 +1364,7 @@
*/
newval = current->pid;
- pagefault_disable();
- curval = futex_atomic_cmpxchg_inatomic(uaddr, 0, newval);
- pagefault_enable();
+ curval = cmpxchg_futex_value_locked(uaddr, 0, newval);
if (unlikely(curval == -EFAULT))
goto uaddr_faulted;
@@ -1398,9 +1407,7 @@
lock_taken = 1;
}
- pagefault_disable();
- curval = futex_atomic_cmpxchg_inatomic(uaddr, uval, newval);
- pagefault_enable();
+ curval = cmpxchg_futex_value_locked(uaddr, uval, newval);
if (unlikely(curval == -EFAULT))
goto uaddr_faulted;
@@ -1428,8 +1435,7 @@
* exit to complete.
*/
queue_unlock(&q, hb);
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
cond_resched();
goto retry;
@@ -1465,8 +1471,7 @@
* Now the futex is queued and we have checked the data, we
* don't want to hold mmap_sem while we sleep.
*/
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
WARN_ON(!q.pi_state);
/*
@@ -1480,8 +1485,7 @@
ret = ret ? 0 : -EWOULDBLOCK;
}
- if (fshared)
- down_read(fshared);
+ futex_lock_mm(fshared);
spin_lock(q.lock_ptr);
if (!ret) {
@@ -1518,8 +1522,7 @@
/* Unqueue and drop the lock */
unqueue_me_pi(&q);
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
return ret != -EINTR ? ret : -ERESTARTNOINTR;
@@ -1527,8 +1530,7 @@
queue_unlock(&q, hb);
out_release_sem:
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
return ret;
uaddr_faulted:
@@ -1550,8 +1552,7 @@
goto retry_unlocked;
}
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
ret = get_user(uval, uaddr);
if (!ret && (uval != -EFAULT))
@@ -1585,8 +1586,7 @@
/*
* First take all the futex related locks:
*/
- if (fshared)
- down_read(fshared);
+ futex_lock_mm(fshared);
ret = get_futex_key(uaddr, fshared, &key);
if (unlikely(ret != 0))
@@ -1601,11 +1601,9 @@
* again. If it succeeds then we can return without waking
* anyone else up:
*/
- if (!(uval & FUTEX_OWNER_DIED)) {
- pagefault_disable();
- uval = futex_atomic_cmpxchg_inatomic(uaddr, current->pid, 0);
- pagefault_enable();
- }
+ if (!(uval & FUTEX_OWNER_DIED))
+ uval = cmpxchg_futex_value_locked(uaddr, current->pid, 0);
+
if (unlikely(uval == -EFAULT))
goto pi_faulted;
@@ -1647,8 +1645,7 @@
out_unlock:
spin_unlock(&hb->lock);
out:
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
return ret;
@@ -1671,8 +1668,7 @@
goto retry_unlocked;
}
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
ret = get_user(uval, uaddr);
if (!ret && (uval != -EFAULT))
@@ -1729,8 +1725,8 @@
if (printk_timed_ratelimit(&printk_interval, 60 * 60 * 1000)) {
printk(KERN_WARNING "Process `%s' used FUTEX_FD, which "
- "will be removed from the kernel in June 2007\n",
- current->comm);
+ "will be removed from the kernel in June 2007\n",
+ current->comm);
}
ret = -EINVAL;
@@ -1908,10 +1904,8 @@
* Wake robust non-PI futexes here. The wakeup of
* PI futexes happens in exit_pi_state():
*/
- if (!pi) {
- if (uval & FUTEX_WAITERS)
+ if (!pi && (uval & FUTEX_WAITERS))
futex_wake(uaddr, &curr->mm->mmap_sem, 1);
- }
}
return 0;
}