[PATCH -mm] FUTEX: Tidy up the code - V2

From: Thomas Gleixner
Date: Sat Jun 23 2007 - 06:00:49 EST

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Subject: 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@xxxxxxxxxxxxx>

---
kernel/futex.c | 138 ++++++++++++++++++++++--------------------------
kernel/rtmutex-debug.c | 6 --
kernel/rtmutex.c | 6 --
kernel/rtmutex_common.h | 9 ++-
4 files changed, 74 insertions(+), 85 deletions(-)

Index: linux-2.6/kernel/futex.c
===================================================================
--- linux-2.6.orig/kernel/futex.c 2007-06-23 11:39:20.000000000 +0200
+++ linux-2.6/kernel/futex.c 2007-06-23 11:39:20.000000000 +0200
@@ -121,6 +121,24 @@ static struct futex_hash_bucket futex_qu
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 @@ void drop_futex_key_refs(union futex_key
}
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 @@ static int wake_futex_pi(u32 __user *uad

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 @@ static int unlock_futex_pi(u32 __user *u
* 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 @@ static int futex_wake(u32 __user *uaddr,
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 @@ static int futex_wake(u32 __user *uaddr,

spin_unlock(&hb->lock);
out:
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
return ret;
}

@@ -746,8 +769,7 @@ futex_wake_op(u32 __user *uaddr1, struct
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 @@ retry:
*/
if (attempt++) {
ret = futex_handle_fault((unsigned long)uaddr2,
- fshared, attempt);
+ fshared, attempt);
if (ret)
goto out;
goto retry;
@@ -803,8 +825,7 @@ retry:
* 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 @@ retry:
if (hb1 != hb2)
spin_unlock(&hb2->lock);
out:
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
+
return ret;
}

@@ -861,8 +882,7 @@ static int futex_requeue(u32 __user *uad
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 @@ static int futex_requeue(u32 __user *uad
* 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 @@ out_unlock:
drop_futex_key_refs(&key1);

out:
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
return ret;
}

@@ -1113,10 +1131,7 @@ static int fixup_pi_state_owner(u32 __us
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 @@ static int fixup_pi_state_owner(u32 __us
#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 @@ static int futex_wait(u32 __user *uaddr,

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 @@ static int futex_wait(u32 __user *uaddr,
* 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 @@ static int futex_wait(u32 __user *uaddr,
* 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 @@ static int futex_wait(u32 __user *uaddr,
queue_unlock(&q, hb);

out_release_sem:
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
return ret;
}

@@ -1333,8 +1345,7 @@ static int futex_lock_pi(u32 __user *uad

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 @@ static int futex_lock_pi(u32 __user *uad
*/
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 @@ static int futex_lock_pi(u32 __user *uad
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 @@ static int futex_lock_pi(u32 __user *uad
* exit to complete.
*/
queue_unlock(&q, hb);
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
cond_resched();
goto retry;

@@ -1465,8 +1471,7 @@ static int futex_lock_pi(u32 __user *uad
* 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 @@ static int futex_lock_pi(u32 __user *uad
ret = ret ? 0 : -EWOULDBLOCK;
}

- if (fshared)
- down_read(fshared);
+ futex_lock_mm(fshared);
spin_lock(q.lock_ptr);

if (!ret) {
@@ -1518,8 +1522,7 @@ static int futex_lock_pi(u32 __user *uad

/* 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 @@ static int futex_lock_pi(u32 __user *uad
queue_unlock(&q, hb);

out_release_sem:
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);
return ret;

uaddr_faulted:
@@ -1550,8 +1552,7 @@ static int futex_lock_pi(u32 __user *uad
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 @@ retry:
/*
* 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 @@ retry_unlocked:
* 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 @@ retry_unlocked:
out_unlock:
spin_unlock(&hb->lock);
out:
- if (fshared)
- up_read(fshared);
+ futex_unlock_mm(fshared);

return ret;

@@ -1671,8 +1668,7 @@ pi_faulted:
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 @@ static int futex_fd(u32 __user *uaddr, i

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 @@ retry:
* 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;
}
Index: linux-2.6/kernel/rtmutex-debug.c
===================================================================
--- linux-2.6.orig/kernel/rtmutex-debug.c 2007-06-23 11:39:20.000000000 +0200
+++ linux-2.6/kernel/rtmutex-debug.c 2007-06-23 11:39:20.000000000 +0200
@@ -29,12 +29,6 @@

#include "rtmutex_common.h"

-#ifdef CONFIG_DEBUG_RT_MUTEXES
-# include "rtmutex-debug.h"
-#else
-# include "rtmutex.h"
-#endif
-
# define TRACE_WARN_ON(x) WARN_ON(x)
# define TRACE_BUG_ON(x) BUG_ON(x)

Index: linux-2.6/kernel/rtmutex.c
===================================================================
--- linux-2.6.orig/kernel/rtmutex.c 2007-06-23 11:39:20.000000000 +0200
+++ linux-2.6/kernel/rtmutex.c 2007-06-23 11:39:20.000000000 +0200
@@ -17,12 +17,6 @@

#include "rtmutex_common.h"

-#ifdef CONFIG_DEBUG_RT_MUTEXES
-# include "rtmutex-debug.h"
-#else
-# include "rtmutex.h"
-#endif
-
/*
* lock->owner state tracking:
*
Index: linux-2.6/kernel/rtmutex_common.h
===================================================================
--- linux-2.6.orig/kernel/rtmutex_common.h 2007-06-23 11:39:20.000000000 +0200
+++ linux-2.6/kernel/rtmutex_common.h 2007-06-23 11:39:20.000000000 +0200
@@ -103,7 +103,7 @@ static inline struct task_struct *rt_mut

static inline struct task_struct *rt_mutex_real_owner(struct rt_mutex *lock)
{
- return (struct task_struct *)
+ return (struct task_struct *)
((unsigned long)lock->owner & ~RT_MUTEX_HAS_WAITERS);
}

@@ -120,4 +120,11 @@ extern void rt_mutex_init_proxy_locked(s
struct task_struct *proxy_owner);
extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
struct task_struct *proxy_owner);
+
+#ifdef CONFIG_DEBUG_RT_MUTEXES
+# include "rtmutex-debug.h"
+#else
+# include "rtmutex.h"
+#endif
+
#endif

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Next message: Christoph Hellwig: "Re: [patch 03/10] Allow userspace applications to use marker.h to parse the markers section in the kernel binary."
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In reply to: Thomas Gleixner: "[PATCH] FUTEX: Restore the dropped ERSCH fix"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]