* Removed page pinning, fix privately mapped COW pages and other cleanups
* (C) Copyright 2003, 2004 Jamie Lokier
*
- * Robust futex support started by Ingo Molnar
- * (C) Copyright 2006 Red Hat Inc, All Rights Reserved
- * Thanks to Thomas Gleixner for suggestions, analysis and fixes.
- *
- * PI-futex support started by Ingo Molnar and Thomas Gleixner
- * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
- * Copyright (C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
- *
* Thanks to Ben LaHaise for yelling "hashed waitqueues" loudly
* enough at me, Linus for the original (flawed) idea, Matthew
* Kirkwood for proof-of-concept implementation.
#include <linux/signal.h>
#include <asm/futex.h>
-#include "rtmutex_common.h"
-
#define FUTEX_HASHBITS (CONFIG_BASE_SMALL ? 4 : 8)
/*
int offset;
} shared;
struct {
- unsigned long address;
+ unsigned long uaddr;
struct mm_struct *mm;
int offset;
} private;
} both;
};
-/*
- * Priority Inheritance state:
- */
-struct futex_pi_state {
- /*
- * list of 'owned' pi_state instances - these have to be
- * cleaned up in do_exit() if the task exits prematurely:
- */
- struct list_head list;
-
- /*
- * The PI object:
- */
- struct rt_mutex pi_mutex;
-
- struct task_struct *owner;
- atomic_t refcount;
-
- union futex_key key;
-};
-
/*
* We use this hashed waitqueue instead of a normal wait_queue_t, so
* we can wake only the relevant ones (hashed queues may be shared).
struct list_head list;
wait_queue_head_t waiters;
- /* Which hash list lock to use: */
+ /* Which hash list lock to use. */
spinlock_t *lock_ptr;
- /* Key which the futex is hashed on: */
+ /* Key which the futex is hashed on. */
union futex_key key;
- /* For fd, sigio sent using these: */
+ /* For fd, sigio sent using these. */
int fd;
struct file *filp;
-
- /* Optional priority inheritance state: */
- struct futex_pi_state *pi_state;
- struct task_struct *task;
};
/*
*
* Should be called with ¤t->mm->mmap_sem but NOT any spinlocks.
*/
-static int get_futex_key(u32 __user *uaddr, union futex_key *key)
+static int get_futex_key(unsigned long uaddr, union futex_key *key)
{
- unsigned long address = (unsigned long)uaddr;
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
struct page *page;
/*
* The futex address must be "naturally" aligned.
*/
- key->both.offset = address % PAGE_SIZE;
+ key->both.offset = uaddr % PAGE_SIZE;
if (unlikely((key->both.offset % sizeof(u32)) != 0))
return -EINVAL;
- address -= key->both.offset;
+ uaddr -= key->both.offset;
/*
* The futex is hashed differently depending on whether
* it's in a shared or private mapping. So check vma first.
*/
- vma = find_extend_vma(mm, address);
+ vma = find_extend_vma(mm, uaddr);
if (unlikely(!vma))
return -EFAULT;
*/
if (likely(!(vma->vm_flags & VM_MAYSHARE))) {
key->private.mm = mm;
- key->private.address = address;
+ key->private.uaddr = uaddr;
return 0;
}
key->shared.inode = vma->vm_file->f_dentry->d_inode;
key->both.offset++; /* Bit 0 of offset indicates inode-based key. */
if (likely(!(vma->vm_flags & VM_NONLINEAR))) {
- key->shared.pgoff = (((address - vma->vm_start) >> PAGE_SHIFT)
+ key->shared.pgoff = (((uaddr - vma->vm_start) >> PAGE_SHIFT)
+ vma->vm_pgoff);
return 0;
}
* from swap. But that's a lot of code to duplicate here
* for a rare case, so we simply fetch the page.
*/
- err = get_user_pages(current, mm, address, 1, 0, 0, &page, NULL);
+ err = get_user_pages(current, mm, uaddr, 1, 0, 0, &page, NULL);
if (err >= 0) {
key->shared.pgoff =
page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
}
}
-static inline int get_futex_value_locked(u32 *dest, u32 __user *from)
+static inline int get_futex_value_locked(int *dest, int __user *from)
{
int ret;
inc_preempt_count();
- ret = __copy_from_user_inatomic(dest, from, sizeof(u32));
+ ret = __copy_from_user_inatomic(dest, from, sizeof(int));
dec_preempt_count();
return ret ? -EFAULT : 0;
}
-/*
- * Fault handling. Called with current->mm->mmap_sem held.
- */
-static int futex_handle_fault(unsigned long address, int attempt)
-{
- struct vm_area_struct * vma;
- struct mm_struct *mm = current->mm;
-
- if (attempt > 2 || !(vma = find_vma(mm, address)) ||
- vma->vm_start > address || !(vma->vm_flags & VM_WRITE))
- return -EFAULT;
-
- switch (handle_mm_fault(mm, vma, address, 1)) {
- case VM_FAULT_MINOR:
- current->min_flt++;
- break;
- case VM_FAULT_MAJOR:
- current->maj_flt++;
- break;
- default:
- return -EFAULT;
- }
- return 0;
-}
-
-/*
- * PI code:
- */
-static int refill_pi_state_cache(void)
-{
- struct futex_pi_state *pi_state;
-
- if (likely(current->pi_state_cache))
- return 0;
-
- pi_state = kmalloc(sizeof(*pi_state), GFP_KERNEL);
-
- if (!pi_state)
- return -ENOMEM;
-
- memset(pi_state, 0, sizeof(*pi_state));
- INIT_LIST_HEAD(&pi_state->list);
- /* pi_mutex gets initialized later */
- pi_state->owner = NULL;
- atomic_set(&pi_state->refcount, 1);
-
- current->pi_state_cache = pi_state;
-
- return 0;
-}
-
-static struct futex_pi_state * alloc_pi_state(void)
-{
- struct futex_pi_state *pi_state = current->pi_state_cache;
-
- WARN_ON(!pi_state);
- current->pi_state_cache = NULL;
-
- return pi_state;
-}
-
-static void free_pi_state(struct futex_pi_state *pi_state)
-{
- if (!atomic_dec_and_test(&pi_state->refcount))
- return;
-
- /*
- * If pi_state->owner is NULL, the owner is most probably dying
- * and has cleaned up the pi_state already
- */
- if (pi_state->owner) {
- spin_lock_irq(&pi_state->owner->pi_lock);
- list_del_init(&pi_state->list);
- spin_unlock_irq(&pi_state->owner->pi_lock);
-
- rt_mutex_proxy_unlock(&pi_state->pi_mutex, pi_state->owner);
- }
-
- if (current->pi_state_cache)
- kfree(pi_state);
- else {
- /*
- * pi_state->list is already empty.
- * clear pi_state->owner.
- * refcount is at 0 - put it back to 1.
- */
- pi_state->owner = NULL;
- atomic_set(&pi_state->refcount, 1);
- current->pi_state_cache = pi_state;
- }
-}
-
-/*
- * Look up the task based on what TID userspace gave us.
- * We dont trust it.
- */
-static struct task_struct * futex_find_get_task(pid_t pid)
-{
- struct task_struct *p;
-
- read_lock(&tasklist_lock);
- p = find_task_by_pid(pid);
- if (!p)
- goto out_unlock;
- if ((current->euid != p->euid) && (current->euid != p->uid)) {
- p = NULL;
- goto out_unlock;
- }
- if (p->exit_state != 0) {
- p = NULL;
- goto out_unlock;
- }
- get_task_struct(p);
-out_unlock:
- read_unlock(&tasklist_lock);
-
- return p;
-}
-
-/*
- * This task is holding PI mutexes at exit time => bad.
- * Kernel cleans up PI-state, but userspace is likely hosed.
- * (Robust-futex cleanup is separate and might save the day for userspace.)
- */
-void exit_pi_state_list(struct task_struct *curr)
-{
- struct list_head *next, *head = &curr->pi_state_list;
- struct futex_pi_state *pi_state;
- struct futex_hash_bucket *hb;
- union futex_key key;
-
- /*
- * We are a ZOMBIE and nobody can enqueue itself on
- * pi_state_list anymore, but we have to be careful
- * versus waiters unqueueing themselves:
- */
- spin_lock_irq(&curr->pi_lock);
- while (!list_empty(head)) {
-
- next = head->next;
- pi_state = list_entry(next, struct futex_pi_state, list);
- key = pi_state->key;
- hb = hash_futex(&key);
- spin_unlock_irq(&curr->pi_lock);
-
- spin_lock(&hb->lock);
-
- spin_lock_irq(&curr->pi_lock);
- /*
- * We dropped the pi-lock, so re-check whether this
- * task still owns the PI-state:
- */
- if (head->next != next) {
- spin_unlock(&hb->lock);
- continue;
- }
-
- WARN_ON(pi_state->owner != curr);
- WARN_ON(list_empty(&pi_state->list));
- list_del_init(&pi_state->list);
- pi_state->owner = NULL;
- spin_unlock_irq(&curr->pi_lock);
-
- rt_mutex_unlock(&pi_state->pi_mutex);
-
- spin_unlock(&hb->lock);
-
- spin_lock_irq(&curr->pi_lock);
- }
- spin_unlock_irq(&curr->pi_lock);
-}
-
-static int
-lookup_pi_state(u32 uval, struct futex_hash_bucket *hb, struct futex_q *me)
-{
- struct futex_pi_state *pi_state = NULL;
- struct futex_q *this, *next;
- struct list_head *head;
- struct task_struct *p;
- pid_t pid;
-
- head = &hb->chain;
-
- list_for_each_entry_safe(this, next, head, list) {
- if (match_futex(&this->key, &me->key)) {
- /*
- * Another waiter already exists - bump up
- * the refcount and return its pi_state:
- */
- pi_state = this->pi_state;
- /*
- * Userspace might have messed up non PI and PI futexes
- */
- if (unlikely(!pi_state))
- return -EINVAL;
-
- WARN_ON(!atomic_read(&pi_state->refcount));
-
- atomic_inc(&pi_state->refcount);
- me->pi_state = pi_state;
-
- return 0;
- }
- }
-
- /*
- * We are the first waiter - try to look up the real owner and attach
- * the new pi_state to it, but bail out when the owner died bit is set
- * and TID = 0:
- */
- pid = uval & FUTEX_TID_MASK;
- if (!pid && (uval & FUTEX_OWNER_DIED))
- return -ESRCH;
- p = futex_find_get_task(pid);
- if (!p)
- return -ESRCH;
-
- pi_state = alloc_pi_state();
-
- /*
- * Initialize the pi_mutex in locked state and make 'p'
- * the owner of it:
- */
- rt_mutex_init_proxy_locked(&pi_state->pi_mutex, p);
-
- /* Store the key for possible exit cleanups: */
- pi_state->key = me->key;
-
- spin_lock_irq(&p->pi_lock);
- WARN_ON(!list_empty(&pi_state->list));
- list_add(&pi_state->list, &p->pi_state_list);
- pi_state->owner = p;
- spin_unlock_irq(&p->pi_lock);
-
- put_task_struct(p);
-
- me->pi_state = pi_state;
-
- return 0;
-}
-
/*
* The hash bucket lock must be held when this is called.
* Afterwards, the futex_q must not be accessed.
q->lock_ptr = NULL;
}
-static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this)
-{
- struct task_struct *new_owner;
- struct futex_pi_state *pi_state = this->pi_state;
- u32 curval, newval;
-
- if (!pi_state)
- return -EINVAL;
-
- new_owner = rt_mutex_next_owner(&pi_state->pi_mutex);
-
- /*
- * This happens when we have stolen the lock and the original
- * pending owner did not enqueue itself back on the rt_mutex.
- * Thats not a tragedy. We know that way, that a lock waiter
- * is on the fly. We make the futex_q waiter the pending owner.
- */
- if (!new_owner)
- new_owner = this->task;
-
- /*
- * We pass it to the next owner. (The WAITERS bit is always
- * kept enabled while there is PI state around. We must also
- * preserve the owner died bit.)
- */
- if (!(uval & FUTEX_OWNER_DIED)) {
- newval = FUTEX_WAITERS | new_owner->pid;
-
- inc_preempt_count();
- curval = futex_atomic_cmpxchg_inatomic(uaddr, uval, newval);
- dec_preempt_count();
- if (curval == -EFAULT)
- return -EFAULT;
- if (curval != uval)
- return -EINVAL;
- }
-
- spin_lock_irq(&pi_state->owner->pi_lock);
- WARN_ON(list_empty(&pi_state->list));
- list_del_init(&pi_state->list);
- spin_unlock_irq(&pi_state->owner->pi_lock);
-
- spin_lock_irq(&new_owner->pi_lock);
- WARN_ON(!list_empty(&pi_state->list));
- list_add(&pi_state->list, &new_owner->pi_state_list);
- pi_state->owner = new_owner;
- spin_unlock_irq(&new_owner->pi_lock);
-
- rt_mutex_unlock(&pi_state->pi_mutex);
-
- return 0;
-}
-
-static int unlock_futex_pi(u32 __user *uaddr, u32 uval)
-{
- u32 oldval;
-
- /*
- * There is no waiter, so we unlock the futex. The owner died
- * bit has not to be preserved here. We are the owner:
- */
- inc_preempt_count();
- oldval = futex_atomic_cmpxchg_inatomic(uaddr, uval, 0);
- dec_preempt_count();
-
- if (oldval == -EFAULT)
- return oldval;
- if (oldval != uval)
- return -EAGAIN;
-
- return 0;
-}
-
-/*
- * Express the locking dependencies for lockdep:
- */
-static inline void
-double_lock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2)
-{
- if (hb1 <= hb2) {
- spin_lock(&hb1->lock);
- if (hb1 < hb2)
- spin_lock_nested(&hb2->lock, SINGLE_DEPTH_NESTING);
- } else { /* hb1 > hb2 */
- spin_lock(&hb2->lock);
- spin_lock_nested(&hb1->lock, SINGLE_DEPTH_NESTING);
- }
-}
-
/*
* Wake up all waiters hashed on the physical page that is mapped
* to this virtual address:
*/
-static int futex_wake(u32 __user *uaddr, int nr_wake)
+static int futex_wake(unsigned long uaddr, int nr_wake)
{
- struct futex_hash_bucket *hb;
- struct futex_q *this, *next;
- struct list_head *head;
union futex_key key;
+ struct futex_hash_bucket *bh;
+ struct list_head *head;
+ struct futex_q *this, *next;
int ret;
down_read(¤t->mm->mmap_sem);
if (unlikely(ret != 0))
goto out;
- hb = hash_futex(&key);
- spin_lock(&hb->lock);
- head = &hb->chain;
+ bh = hash_futex(&key);
+ spin_lock(&bh->lock);
+ head = &bh->chain;
list_for_each_entry_safe(this, next, head, list) {
if (match_futex (&this->key, &key)) {
- if (this->pi_state) {
- ret = -EINVAL;
- break;
- }
wake_futex(this);
if (++ret >= nr_wake)
break;
}
}
- spin_unlock(&hb->lock);
+ spin_unlock(&bh->lock);
out:
up_read(¤t->mm->mmap_sem);
return ret;
* Wake up all waiters hashed on the physical page that is mapped
* to this virtual address:
*/
-static int
-futex_wake_op(u32 __user *uaddr1, u32 __user *uaddr2,
- int nr_wake, int nr_wake2, int op)
+static int futex_wake_op(unsigned long uaddr1, unsigned long uaddr2, int nr_wake, int nr_wake2, int op)
{
union futex_key key1, key2;
- struct futex_hash_bucket *hb1, *hb2;
+ struct futex_hash_bucket *bh1, *bh2;
struct list_head *head;
struct futex_q *this, *next;
int ret, op_ret, attempt = 0;
if (unlikely(ret != 0))
goto out;
- hb1 = hash_futex(&key1);
- hb2 = hash_futex(&key2);
+ bh1 = hash_futex(&key1);
+ bh2 = hash_futex(&key2);
retry:
- double_lock_hb(hb1, hb2);
+ if (bh1 < bh2)
+ spin_lock(&bh1->lock);
+ spin_lock(&bh2->lock);
+ if (bh1 > bh2)
+ spin_lock(&bh1->lock);
- op_ret = futex_atomic_op_inuser(op, uaddr2);
+ op_ret = futex_atomic_op_inuser(op, (int __user *)uaddr2);
if (unlikely(op_ret < 0)) {
- u32 dummy;
+ int dummy;
- spin_unlock(&hb1->lock);
- if (hb1 != hb2)
- spin_unlock(&hb2->lock);
+ spin_unlock(&bh1->lock);
+ if (bh1 != bh2)
+ spin_unlock(&bh2->lock);
#ifndef CONFIG_MMU
- /*
- * we don't get EFAULT from MMU faults if we don't have an MMU,
- * but we might get them from range checking
- */
+ /* we don't get EFAULT from MMU faults if we don't have an MMU,
+ * but we might get them from range checking */
ret = op_ret;
goto out;
#endif
goto out;
}
- /*
- * futex_atomic_op_inuser needs to both read and write
+ /* futex_atomic_op_inuser needs to both read and write
* *(int __user *)uaddr2, but we can't modify it
* non-atomically. Therefore, if get_user below is not
* enough, we need to handle the fault ourselves, while
- * still holding the mmap_sem.
- */
+ * still holding the mmap_sem. */
if (attempt++) {
- if (futex_handle_fault((unsigned long)uaddr2,
- attempt)) {
- ret = -EFAULT;
+ struct vm_area_struct * vma;
+ struct mm_struct *mm = current->mm;
+
+ ret = -EFAULT;
+ if (attempt >= 2 ||
+ !(vma = find_vma(mm, uaddr2)) ||
+ vma->vm_start > uaddr2 ||
+ !(vma->vm_flags & VM_WRITE))
+ goto out;
+
+ switch (handle_mm_fault(mm, vma, uaddr2, 1)) {
+ case VM_FAULT_MINOR:
+ current->min_flt++;
+ break;
+ case VM_FAULT_MAJOR:
+ current->maj_flt++;
+ break;
+ default:
goto out;
}
goto retry;
}
- /*
- * If we would have faulted, release mmap_sem,
- * fault it in and start all over again.
- */
+ /* If we would have faulted, release mmap_sem,
+ * fault it in and start all over again. */
up_read(¤t->mm->mmap_sem);
- ret = get_user(dummy, uaddr2);
+ ret = get_user(dummy, (int __user *)uaddr2);
if (ret)
return ret;
goto retryfull;
}
- head = &hb1->chain;
+ head = &bh1->chain;
list_for_each_entry_safe(this, next, head, list) {
if (match_futex (&this->key, &key1)) {
}
if (op_ret > 0) {
- head = &hb2->chain;
+ head = &bh2->chain;
op_ret = 0;
list_for_each_entry_safe(this, next, head, list) {
ret += op_ret;
}
- spin_unlock(&hb1->lock);
- if (hb1 != hb2)
- spin_unlock(&hb2->lock);
+ spin_unlock(&bh1->lock);
+ if (bh1 != bh2)
+ spin_unlock(&bh2->lock);
out:
up_read(¤t->mm->mmap_sem);
return ret;
* Requeue all waiters hashed on one physical page to another
* physical page.
*/
-static int futex_requeue(u32 __user *uaddr1, u32 __user *uaddr2,
- int nr_wake, int nr_requeue, u32 *cmpval)
+static int futex_requeue(unsigned long uaddr1, unsigned long uaddr2,
+ int nr_wake, int nr_requeue, int *valp)
{
union futex_key key1, key2;
- struct futex_hash_bucket *hb1, *hb2;
+ struct futex_hash_bucket *bh1, *bh2;
struct list_head *head1;
struct futex_q *this, *next;
int ret, drop_count = 0;
if (unlikely(ret != 0))
goto out;
- hb1 = hash_futex(&key1);
- hb2 = hash_futex(&key2);
+ bh1 = hash_futex(&key1);
+ bh2 = hash_futex(&key2);
- double_lock_hb(hb1, hb2);
+ if (bh1 < bh2)
+ spin_lock(&bh1->lock);
+ spin_lock(&bh2->lock);
+ if (bh1 > bh2)
+ spin_lock(&bh1->lock);
- if (likely(cmpval != NULL)) {
- u32 curval;
+ if (likely(valp != NULL)) {
+ int curval;
- ret = get_futex_value_locked(&curval, uaddr1);
+ ret = get_futex_value_locked(&curval, (int __user *)uaddr1);
if (unlikely(ret)) {
- spin_unlock(&hb1->lock);
- if (hb1 != hb2)
- spin_unlock(&hb2->lock);
+ spin_unlock(&bh1->lock);
+ if (bh1 != bh2)
+ spin_unlock(&bh2->lock);
- /*
- * If we would have faulted, release mmap_sem, fault
+ /* If we would have faulted, release mmap_sem, fault
* it in and start all over again.
*/
up_read(¤t->mm->mmap_sem);
- ret = get_user(curval, uaddr1);
+ ret = get_user(curval, (int __user *)uaddr1);
if (!ret)
goto retry;
return ret;
}
- if (curval != *cmpval) {
+ if (curval != *valp) {
ret = -EAGAIN;
goto out_unlock;
}
}
- head1 = &hb1->chain;
+ head1 = &bh1->chain;
list_for_each_entry_safe(this, next, head1, list) {
if (!match_futex (&this->key, &key1))
continue;
if (++ret <= nr_wake) {
wake_futex(this);
} else {
- /*
- * If key1 and key2 hash to the same bucket, no need to
- * requeue.
- */
- if (likely(head1 != &hb2->chain)) {
- list_move_tail(&this->list, &hb2->chain);
- this->lock_ptr = &hb2->lock;
- }
+ list_move_tail(&this->list, &bh2->chain);
+ this->lock_ptr = &bh2->lock;
this->key = key2;
get_key_refs(&key2);
drop_count++;
if (ret - nr_wake >= nr_requeue)
break;
+ /* Make sure to stop if key1 == key2 */
+ if (head1 == &bh2->chain && head1 != &next->list)
+ head1 = &this->list;
}
}
out_unlock:
- spin_unlock(&hb1->lock);
- if (hb1 != hb2)
- spin_unlock(&hb2->lock);
+ spin_unlock(&bh1->lock);
+ if (bh1 != bh2)
+ spin_unlock(&bh2->lock);
/* drop_key_refs() must be called outside the spinlocks. */
while (--drop_count >= 0)
static inline struct futex_hash_bucket *
queue_lock(struct futex_q *q, int fd, struct file *filp)
{
- struct futex_hash_bucket *hb;
+ struct futex_hash_bucket *bh;
q->fd = fd;
q->filp = filp;
init_waitqueue_head(&q->waiters);
get_key_refs(&q->key);
- hb = hash_futex(&q->key);
- q->lock_ptr = &hb->lock;
+ bh = hash_futex(&q->key);
+ q->lock_ptr = &bh->lock;
- spin_lock(&hb->lock);
- return hb;
+ spin_lock(&bh->lock);
+ return bh;
}
-static inline void __queue_me(struct futex_q *q, struct futex_hash_bucket *hb)
+static inline void __queue_me(struct futex_q *q, struct futex_hash_bucket *bh)
{
- list_add_tail(&q->list, &hb->chain);
- q->task = current;
- spin_unlock(&hb->lock);
+ list_add_tail(&q->list, &bh->chain);
+ spin_unlock(&bh->lock);
}
static inline void
-queue_unlock(struct futex_q *q, struct futex_hash_bucket *hb)
+queue_unlock(struct futex_q *q, struct futex_hash_bucket *bh)
{
- spin_unlock(&hb->lock);
+ spin_unlock(&bh->lock);
drop_key_refs(&q->key);
}
/* The key must be already stored in q->key. */
static void queue_me(struct futex_q *q, int fd, struct file *filp)
{
- struct futex_hash_bucket *hb;
-
- hb = queue_lock(q, fd, filp);
- __queue_me(q, hb);
+ struct futex_hash_bucket *bh;
+ bh = queue_lock(q, fd, filp);
+ __queue_me(q, bh);
}
/* Return 1 if we were still queued (ie. 0 means we were woken) */
static int unqueue_me(struct futex_q *q)
{
- spinlock_t *lock_ptr;
int ret = 0;
+ spinlock_t *lock_ptr;
/* In the common case we don't take the spinlock, which is nice. */
retry:
}
WARN_ON(list_empty(&q->list));
list_del(&q->list);
-
- BUG_ON(q->pi_state);
-
spin_unlock(lock_ptr);
ret = 1;
}
return ret;
}
-/*
- * PI futexes can not be requeued and must remove themself from the
- * hash bucket. The hash bucket lock is held on entry and dropped here.
- */
-static void unqueue_me_pi(struct futex_q *q, struct futex_hash_bucket *hb)
+static int futex_wait(unsigned long uaddr, int val, unsigned long time)
{
- WARN_ON(list_empty(&q->list));
- list_del(&q->list);
-
- BUG_ON(!q->pi_state);
- free_pi_state(q->pi_state);
- q->pi_state = NULL;
-
- spin_unlock(&hb->lock);
-
- drop_key_refs(&q->key);
-}
-
-static int futex_wait(u32 __user *uaddr, u32 val, unsigned long time)
-{
- struct task_struct *curr = current;
- DECLARE_WAITQUEUE(wait, curr);
- struct futex_hash_bucket *hb;
+ DECLARE_WAITQUEUE(wait, current);
+ int ret, curval;
struct futex_q q;
- u32 uval;
- int ret;
+ struct futex_hash_bucket *bh;
- q.pi_state = NULL;
retry:
- down_read(&curr->mm->mmap_sem);
+ down_read(¤t->mm->mmap_sem);
ret = get_futex_key(uaddr, &q.key);
if (unlikely(ret != 0))
goto out_release_sem;
- hb = queue_lock(&q, -1, NULL);
+ bh = queue_lock(&q, -1, NULL);
/*
* Access the page AFTER the futex is queued.
* We hold the mmap semaphore, so the mapping cannot have changed
* since we looked it up in get_futex_key.
*/
- ret = get_futex_value_locked(&uval, uaddr);
+
+ ret = get_futex_value_locked(&curval, (int __user *)uaddr);
if (unlikely(ret)) {
- queue_unlock(&q, hb);
+ queue_unlock(&q, bh);
- /*
- * If we would have faulted, release mmap_sem, fault it in and
+ /* If we would have faulted, release mmap_sem, fault it in and
* start all over again.
*/
- up_read(&curr->mm->mmap_sem);
+ up_read(¤t->mm->mmap_sem);
- ret = get_user(uval, uaddr);
+ ret = get_user(curval, (int __user *)uaddr);
if (!ret)
goto retry;
return ret;
}
- ret = -EWOULDBLOCK;
- if (uval != val)
- goto out_unlock_release_sem;
+ if (curval != val) {
+ ret = -EWOULDBLOCK;
+ queue_unlock(&q, bh);
+ goto out_release_sem;
+ }
/* Only actually queue if *uaddr contained val. */
- __queue_me(&q, hb);
+ __queue_me(&q, bh);
/*
* Now the futex is queued and we have checked the data, we
* don't want to hold mmap_sem while we sleep.
- */
- up_read(&curr->mm->mmap_sem);
+ */
+ up_read(¤t->mm->mmap_sem);
/*
* There might have been scheduling since the queue_me(), as we
return 0;
if (time == 0)
return -ETIMEDOUT;
- /*
- * We expect signal_pending(current), but another thread may
- * have handled it for us already.
- */
+ /* We expect signal_pending(current), but another thread may
+ * have handled it for us already. */
return -EINTR;
- out_unlock_release_sem:
- queue_unlock(&q, hb);
-
- out_release_sem:
- up_read(&curr->mm->mmap_sem);
- return ret;
-}
-
-/*
- * Userspace tried a 0 -> TID atomic transition of the futex value
- * and failed. The kernel side here does the whole locking operation:
- * if there are waiters then it will block, it does PI, etc. (Due to
- * races the kernel might see a 0 value of the futex too.)
- */
-static int futex_lock_pi(u32 __user *uaddr, int detect, unsigned long sec,
- long nsec, int trylock)
-{
- struct hrtimer_sleeper timeout, *to = NULL;
- struct task_struct *curr = current;
- struct futex_hash_bucket *hb;
- u32 uval, newval, curval;
- struct futex_q q;
- int ret, attempt = 0;
-
- if (refill_pi_state_cache())
- return -ENOMEM;
-
- if (sec != MAX_SCHEDULE_TIMEOUT) {
- to = &timeout;
- hrtimer_init(&to->timer, CLOCK_REALTIME, HRTIMER_ABS);
- hrtimer_init_sleeper(to, current);
- to->timer.expires = ktime_set(sec, nsec);
- }
-
- q.pi_state = NULL;
- retry:
- down_read(&curr->mm->mmap_sem);
-
- ret = get_futex_key(uaddr, &q.key);
- if (unlikely(ret != 0))
- goto out_release_sem;
-
- hb = queue_lock(&q, -1, NULL);
-
- retry_locked:
- /*
- * To avoid races, we attempt to take the lock here again
- * (by doing a 0 -> TID atomic cmpxchg), while holding all
- * the locks. It will most likely not succeed.
- */
- newval = current->pid;
-
- inc_preempt_count();
- curval = futex_atomic_cmpxchg_inatomic(uaddr, 0, newval);
- dec_preempt_count();
-
- if (unlikely(curval == -EFAULT))
- goto uaddr_faulted;
-
- /* We own the lock already */
- if (unlikely((curval & FUTEX_TID_MASK) == current->pid)) {
- if (!detect && 0)
- force_sig(SIGKILL, current);
- ret = -EDEADLK;
- goto out_unlock_release_sem;
- }
-
- /*
- * Surprise - we got the lock. Just return
- * to userspace:
- */
- if (unlikely(!curval))
- goto out_unlock_release_sem;
-
- uval = curval;
- newval = uval | FUTEX_WAITERS;
-
- inc_preempt_count();
- curval = futex_atomic_cmpxchg_inatomic(uaddr, uval, newval);
- dec_preempt_count();
-
- if (unlikely(curval == -EFAULT))
- goto uaddr_faulted;
- if (unlikely(curval != uval))
- goto retry_locked;
-
- /*
- * We dont have the lock. Look up the PI state (or create it if
- * we are the first waiter):
- */
- ret = lookup_pi_state(uval, hb, &q);
-
- if (unlikely(ret)) {
- /*
- * There were no waiters and the owner task lookup
- * failed. When the OWNER_DIED bit is set, then we
- * know that this is a robust futex and we actually
- * take the lock. This is safe as we are protected by
- * the hash bucket lock. We also set the waiters bit
- * unconditionally here, to simplify glibc handling of
- * multiple tasks racing to acquire the lock and
- * cleanup the problems which were left by the dead
- * owner.
- */
- if (curval & FUTEX_OWNER_DIED) {
- uval = newval;
- newval = current->pid |
- FUTEX_OWNER_DIED | FUTEX_WAITERS;
-
- inc_preempt_count();
- curval = futex_atomic_cmpxchg_inatomic(uaddr,
- uval, newval);
- dec_preempt_count();
-
- if (unlikely(curval == -EFAULT))
- goto uaddr_faulted;
- if (unlikely(curval != uval))
- goto retry_locked;
- ret = 0;
- }
- goto out_unlock_release_sem;
- }
-
- /*
- * Only actually queue now that the atomic ops are done:
- */
- __queue_me(&q, hb);
-
- /*
- * Now the futex is queued and we have checked the data, we
- * don't want to hold mmap_sem while we sleep.
- */
- up_read(&curr->mm->mmap_sem);
-
- WARN_ON(!q.pi_state);
- /*
- * Block on the PI mutex:
- */
- if (!trylock)
- ret = rt_mutex_timed_lock(&q.pi_state->pi_mutex, to, 1);
- else {
- ret = rt_mutex_trylock(&q.pi_state->pi_mutex);
- /* Fixup the trylock return value: */
- ret = ret ? 0 : -EWOULDBLOCK;
- }
-
- down_read(&curr->mm->mmap_sem);
- spin_lock(q.lock_ptr);
-
- /*
- * Got the lock. We might not be the anticipated owner if we
- * did a lock-steal - fix up the PI-state in that case.
- */
- if (!ret && q.pi_state->owner != curr) {
- u32 newtid = current->pid | FUTEX_WAITERS;
-
- /* Owner died? */
- if (q.pi_state->owner != NULL) {
- spin_lock_irq(&q.pi_state->owner->pi_lock);
- WARN_ON(list_empty(&q.pi_state->list));
- list_del_init(&q.pi_state->list);
- spin_unlock_irq(&q.pi_state->owner->pi_lock);
- } else
- newtid |= FUTEX_OWNER_DIED;
-
- q.pi_state->owner = current;
-
- spin_lock_irq(¤t->pi_lock);
- WARN_ON(!list_empty(&q.pi_state->list));
- list_add(&q.pi_state->list, ¤t->pi_state_list);
- spin_unlock_irq(¤t->pi_lock);
-
- /* Unqueue and drop the lock */
- unqueue_me_pi(&q, hb);
- up_read(&curr->mm->mmap_sem);
- /*
- * We own it, so we have to replace the pending owner
- * TID. This must be atomic as we have preserve the
- * owner died bit here.
- */
- ret = get_user(uval, uaddr);
- while (!ret) {
- newval = (uval & FUTEX_OWNER_DIED) | newtid;
- curval = futex_atomic_cmpxchg_inatomic(uaddr,
- uval, newval);
- if (curval == -EFAULT)
- ret = -EFAULT;
- if (curval == uval)
- break;
- uval = curval;
- }
- } else {
- /*
- * Catch the rare case, where the lock was released
- * when we were on the way back before we locked
- * the hash bucket.
- */
- if (ret && q.pi_state->owner == curr) {
- if (rt_mutex_trylock(&q.pi_state->pi_mutex))
- ret = 0;
- }
- /* Unqueue and drop the lock */
- unqueue_me_pi(&q, hb);
- up_read(&curr->mm->mmap_sem);
- }
-
- if (!detect && ret == -EDEADLK && 0)
- force_sig(SIGKILL, current);
-
- return ret != -EINTR ? ret : -ERESTARTNOINTR;
-
- out_unlock_release_sem:
- queue_unlock(&q, hb);
-
out_release_sem:
- up_read(&curr->mm->mmap_sem);
- return ret;
-
- uaddr_faulted:
- /*
- * We have to r/w *(int __user *)uaddr, but we can't modify it
- * non-atomically. Therefore, if get_user below is not
- * enough, we need to handle the fault ourselves, while
- * still holding the mmap_sem.
- */
- if (attempt++) {
- if (futex_handle_fault((unsigned long)uaddr, attempt)) {
- ret = -EFAULT;
- goto out_unlock_release_sem;
- }
- goto retry_locked;
- }
-
- queue_unlock(&q, hb);
- up_read(&curr->mm->mmap_sem);
-
- ret = get_user(uval, uaddr);
- if (!ret && (uval != -EFAULT))
- goto retry;
-
- return ret;
-}
-
-/*
- * Userspace attempted a TID -> 0 atomic transition, and failed.
- * This is the in-kernel slowpath: we look up the PI state (if any),
- * and do the rt-mutex unlock.
- */
-static int futex_unlock_pi(u32 __user *uaddr)
-{
- struct futex_hash_bucket *hb;
- struct futex_q *this, *next;
- u32 uval;
- struct list_head *head;
- union futex_key key;
- int ret, attempt = 0;
-
-retry:
- if (get_user(uval, uaddr))
- return -EFAULT;
- /*
- * We release only a lock we actually own:
- */
- if ((uval & FUTEX_TID_MASK) != current->pid)
- return -EPERM;
- /*
- * First take all the futex related locks:
- */
- down_read(¤t->mm->mmap_sem);
-
- ret = get_futex_key(uaddr, &key);
- if (unlikely(ret != 0))
- goto out;
-
- hb = hash_futex(&key);
- spin_lock(&hb->lock);
-
-retry_locked:
- /*
- * To avoid races, try to do the TID -> 0 atomic transition
- * again. If it succeeds then we can return without waking
- * anyone else up:
- */
- if (!(uval & FUTEX_OWNER_DIED)) {
- inc_preempt_count();
- uval = futex_atomic_cmpxchg_inatomic(uaddr, current->pid, 0);
- dec_preempt_count();
- }
-
- if (unlikely(uval == -EFAULT))
- goto pi_faulted;
- /*
- * Rare case: we managed to release the lock atomically,
- * no need to wake anyone else up:
- */
- if (unlikely(uval == current->pid))
- goto out_unlock;
-
- /*
- * Ok, other tasks may need to be woken up - check waiters
- * and do the wakeup if necessary:
- */
- head = &hb->chain;
-
- list_for_each_entry_safe(this, next, head, list) {
- if (!match_futex (&this->key, &key))
- continue;
- ret = wake_futex_pi(uaddr, uval, this);
- /*
- * The atomic access to the futex value
- * generated a pagefault, so retry the
- * user-access and the wakeup:
- */
- if (ret == -EFAULT)
- goto pi_faulted;
- goto out_unlock;
- }
- /*
- * No waiters - kernel unlocks the futex:
- */
- if (!(uval & FUTEX_OWNER_DIED)) {
- ret = unlock_futex_pi(uaddr, uval);
- if (ret == -EFAULT)
- goto pi_faulted;
- }
-
-out_unlock:
- spin_unlock(&hb->lock);
-out:
up_read(¤t->mm->mmap_sem);
-
- return ret;
-
-pi_faulted:
- /*
- * We have to r/w *(int __user *)uaddr, but we can't modify it
- * non-atomically. Therefore, if get_user below is not
- * enough, we need to handle the fault ourselves, while
- * still holding the mmap_sem.
- */
- if (attempt++) {
- if (futex_handle_fault((unsigned long)uaddr, attempt)) {
- ret = -EFAULT;
- goto out_unlock;
- }
- goto retry_locked;
- }
-
- spin_unlock(&hb->lock);
- up_read(¤t->mm->mmap_sem);
-
- ret = get_user(uval, uaddr);
- if (!ret && (uval != -EFAULT))
- goto retry;
-
return ret;
}
unqueue_me(q);
kfree(q);
-
return 0;
}
* Signal allows caller to avoid the race which would occur if they
* set the sigio stuff up afterwards.
*/
-static int futex_fd(u32 __user *uaddr, int signal)
+static int futex_fd(unsigned long uaddr, int signal)
{
struct futex_q *q;
struct file *filp;
err = -ENOMEM;
goto error;
}
- q->pi_state = NULL;
down_read(¤t->mm->mmap_sem);
err = get_futex_key(uaddr, &q->key);
goto out;
}
-/*
- * Support for robust futexes: the kernel cleans up held futexes at
- * thread exit time.
- *
- * Implementation: user-space maintains a per-thread list of locks it
- * is holding. Upon do_exit(), the kernel carefully walks this list,
- * and marks all locks that are owned by this thread with the
- * FUTEX_OWNER_DIED bit, and wakes up a waiter (if any). The list is
- * always manipulated with the lock held, so the list is private and
- * per-thread. Userspace also maintains a per-thread 'list_op_pending'
- * field, to allow the kernel to clean up if the thread dies after
- * acquiring the lock, but just before it could have added itself to
- * the list. There can only be one such pending lock.
- */
-
-/**
- * sys_set_robust_list - set the robust-futex list head of a task
- * @head: pointer to the list-head
- * @len: length of the list-head, as userspace expects
- */
-asmlinkage long
-sys_set_robust_list(struct robust_list_head __user *head,
- size_t len)
-{
- /*
- * The kernel knows only one size for now:
- */
- if (unlikely(len != sizeof(*head)))
- return -EINVAL;
-
- current->robust_list = head;
-
- return 0;
-}
-
-/**
- * sys_get_robust_list - get the robust-futex list head of a task
- * @pid: pid of the process [zero for current task]
- * @head_ptr: pointer to a list-head pointer, the kernel fills it in
- * @len_ptr: pointer to a length field, the kernel fills in the header size
- */
-asmlinkage long
-sys_get_robust_list(int pid, struct robust_list_head __user **head_ptr,
- size_t __user *len_ptr)
-{
- struct robust_list_head *head;
- unsigned long ret;
-
- if (!pid)
- head = current->robust_list;
- else {
- struct task_struct *p;
-
- ret = -ESRCH;
- read_lock(&tasklist_lock);
- p = find_task_by_pid(pid);
- if (!p)
- goto err_unlock;
- ret = -EPERM;
- if ((current->euid != p->euid) && (current->euid != p->uid) &&
- !capable(CAP_SYS_PTRACE))
- goto err_unlock;
- head = p->robust_list;
- read_unlock(&tasklist_lock);
- }
-
- if (put_user(sizeof(*head), len_ptr))
- return -EFAULT;
- return put_user(head, head_ptr);
-
-err_unlock:
- read_unlock(&tasklist_lock);
-
- return ret;
-}
-
-/*
- * Process a futex-list entry, check whether it's owned by the
- * dying task, and do notification if so:
- */
-int handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi)
-{
- u32 uval, nval, mval;
-
-retry:
- if (get_user(uval, uaddr))
- return -1;
-
- if ((uval & FUTEX_TID_MASK) == curr->pid) {
- /*
- * Ok, this dying thread is truly holding a futex
- * of interest. Set the OWNER_DIED bit atomically
- * via cmpxchg, and if the value had FUTEX_WAITERS
- * set, wake up a waiter (if any). (We have to do a
- * futex_wake() even if OWNER_DIED is already set -
- * to handle the rare but possible case of recursive
- * thread-death.) The rest of the cleanup is done in
- * userspace.
- */
- mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED;
- nval = futex_atomic_cmpxchg_inatomic(uaddr, uval, mval);
-
- if (nval == -EFAULT)
- return -1;
-
- if (nval != uval)
- goto retry;
-
- /*
- * Wake robust non-PI futexes here. The wakeup of
- * PI futexes happens in exit_pi_state():
- */
- if (!pi) {
- if (uval & FUTEX_WAITERS)
- futex_wake(uaddr, 1);
- }
- }
- return 0;
-}
-
-/*
- * Fetch a robust-list pointer. Bit 0 signals PI futexes:
- */
-static inline int fetch_robust_entry(struct robust_list __user **entry,
- struct robust_list __user **head, int *pi)
-{
- unsigned long uentry;
-
- if (get_user(uentry, (unsigned long *)head))
- return -EFAULT;
-
- *entry = (void *)(uentry & ~1UL);
- *pi = uentry & 1;
-
- return 0;
-}
-
-/*
- * Walk curr->robust_list (very carefully, it's a userspace list!)
- * and mark any locks found there dead, and notify any waiters.
- *
- * We silently return on any sign of list-walking problem.
- */
-void exit_robust_list(struct task_struct *curr)
-{
- struct robust_list_head __user *head = curr->robust_list;
- struct robust_list __user *entry, *pending;
- unsigned int limit = ROBUST_LIST_LIMIT, pi, pip;
- unsigned long futex_offset;
-
- /*
- * Fetch the list head (which was registered earlier, via
- * sys_set_robust_list()):
- */
- if (fetch_robust_entry(&entry, &head->list.next, &pi))
- return;
- /*
- * Fetch the relative futex offset:
- */
- if (get_user(futex_offset, &head->futex_offset))
- return;
- /*
- * Fetch any possibly pending lock-add first, and handle it
- * if it exists:
- */
- if (fetch_robust_entry(&pending, &head->list_op_pending, &pip))
- return;
-
- if (pending)
- handle_futex_death((void *)pending + futex_offset, curr, pip);
-
- while (entry != &head->list) {
- /*
- * A pending lock might already be on the list, so
- * don't process it twice:
- */
- if (entry != pending)
- if (handle_futex_death((void *)entry + futex_offset,
- curr, pi))
- return;
- /*
- * Fetch the next entry in the list:
- */
- if (fetch_robust_entry(&entry, &entry->next, &pi))
- return;
- /*
- * Avoid excessively long or circular lists:
- */
- if (!--limit)
- break;
-
- cond_resched();
- }
-}
-
-long do_futex(u32 __user *uaddr, int op, u32 val, unsigned long timeout,
- u32 __user *uaddr2, u32 val2, u32 val3)
+long do_futex(unsigned long uaddr, int op, int val, unsigned long timeout,
+ unsigned long uaddr2, int val2, int val3)
{
int ret;
case FUTEX_WAKE_OP:
ret = futex_wake_op(uaddr, uaddr2, val, val2, val3);
break;
- case FUTEX_LOCK_PI:
- ret = futex_lock_pi(uaddr, val, timeout, val2, 0);
- break;
- case FUTEX_UNLOCK_PI:
- ret = futex_unlock_pi(uaddr);
- break;
- case FUTEX_TRYLOCK_PI:
- ret = futex_lock_pi(uaddr, 0, timeout, val2, 1);
- break;
default:
ret = -ENOSYS;
}
}
-asmlinkage long sys_futex(u32 __user *uaddr, int op, u32 val,
+asmlinkage long sys_futex(u32 __user *uaddr, int op, int val,
struct timespec __user *utime, u32 __user *uaddr2,
- u32 val3)
+ int val3)
{
struct timespec t;
unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
- u32 val2 = 0;
+ int val2 = 0;
- if (utime && (op == FUTEX_WAIT || op == FUTEX_LOCK_PI)) {
+ if ((op == FUTEX_WAIT) && utime) {
if (copy_from_user(&t, utime, sizeof(t)) != 0)
return -EFAULT;
- if (!timespec_valid(&t))
- return -EINVAL;
- if (op == FUTEX_WAIT)
- timeout = timespec_to_jiffies(&t) + 1;
- else {
- timeout = t.tv_sec;
- val2 = t.tv_nsec;
- }
+ timeout = timespec_to_jiffies(&t) + 1;
}
/*
* requeue parameter in 'utime' if op == FUTEX_REQUEUE.
*/
- if (op == FUTEX_REQUEUE || op == FUTEX_CMP_REQUEUE)
- val2 = (u32) (unsigned long) utime;
+ if (op >= FUTEX_REQUEUE)
+ val2 = (int) (unsigned long) utime;
- return do_futex(uaddr, op, val, timeout, uaddr2, val2, val3);
+ return do_futex((unsigned long)uaddr, op, val, timeout,
+ (unsigned long)uaddr2, val2, val3);
}
-static int futexfs_get_sb(struct file_system_type *fs_type,
- int flags, const char *dev_name, void *data,
- struct vfsmount *mnt)
+static struct super_block *
+futexfs_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data)
{
- return get_sb_pseudo(fs_type, "futex", NULL, 0xBAD1DEA, mnt);
+ return get_sb_pseudo(fs_type, "futex", NULL, 0xBAD1DEA);
}
static struct file_system_type futex_fs_type = {
git://git.onelab.eu / linux-2.6.git / blobdiff