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Diffstat (limited to 'kernel/futex.c')
-rw-r--r--kernel/futex.c106
1 files changed, 65 insertions, 41 deletions
diff --git a/kernel/futex.c b/kernel/futex.c
index 5a270b5e3f9..600bc9d801f 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -48,6 +48,7 @@
#include <linux/pagemap.h>
#include <linux/syscalls.h>
#include <linux/signal.h>
+#include <linux/module.h>
#include <asm/futex.h>
#include "rtmutex_common.h"
@@ -55,32 +56,6 @@
#define FUTEX_HASHBITS (CONFIG_BASE_SMALL ? 4 : 8)
/*
- * Futexes are matched on equal values of this key.
- * The key type depends on whether it's a shared or private mapping.
- * Don't rearrange members without looking at hash_futex().
- *
- * offset is aligned to a multiple of sizeof(u32) (== 4) by definition.
- * We set bit 0 to indicate if it's an inode-based key.
- */
-union futex_key {
- struct {
- unsigned long pgoff;
- struct inode *inode;
- int offset;
- } shared;
- struct {
- unsigned long address;
- struct mm_struct *mm;
- int offset;
- } private;
- struct {
- unsigned long word;
- void *ptr;
- int offset;
- } both;
-};
-
-/*
* Priority Inheritance state:
*/
struct futex_pi_state {
@@ -175,7 +150,7 @@ static inline int match_futex(union futex_key *key1, union futex_key *key2)
*
* Should be called with &current->mm->mmap_sem but NOT any spinlocks.
*/
-static int get_futex_key(u32 __user *uaddr, union futex_key *key)
+int get_futex_key(u32 __user *uaddr, union futex_key *key)
{
unsigned long address = (unsigned long)uaddr;
struct mm_struct *mm = current->mm;
@@ -246,6 +221,7 @@ static int get_futex_key(u32 __user *uaddr, union futex_key *key)
}
return err;
}
+EXPORT_SYMBOL_GPL(get_futex_key);
/*
* Take a reference to the resource addressed by a key.
@@ -254,7 +230,7 @@ static int get_futex_key(u32 __user *uaddr, union futex_key *key)
* NOTE: mmap_sem MUST be held between get_futex_key() and calling this
* function, if it is called at all. mmap_sem keeps key->shared.inode valid.
*/
-static inline void get_key_refs(union futex_key *key)
+inline void get_futex_key_refs(union futex_key *key)
{
if (key->both.ptr != 0) {
if (key->both.offset & 1)
@@ -263,12 +239,13 @@ static inline void get_key_refs(union futex_key *key)
atomic_inc(&key->private.mm->mm_count);
}
}
+EXPORT_SYMBOL_GPL(get_futex_key_refs);
/*
* Drop a reference to the resource addressed by a key.
* The hash bucket spinlock must not be held.
*/
-static void drop_key_refs(union futex_key *key)
+void drop_futex_key_refs(union futex_key *key)
{
if (key->both.ptr != 0) {
if (key->both.offset & 1)
@@ -277,6 +254,7 @@ static void drop_key_refs(union futex_key *key)
mmdrop(key->private.mm);
}
}
+EXPORT_SYMBOL_GPL(drop_futex_key_refs);
static inline int get_futex_value_locked(u32 *dest, u32 __user *from)
{
@@ -873,7 +851,7 @@ static int futex_requeue(u32 __user *uaddr1, u32 __user *uaddr2,
this->lock_ptr = &hb2->lock;
}
this->key = key2;
- get_key_refs(&key2);
+ get_futex_key_refs(&key2);
drop_count++;
if (ret - nr_wake >= nr_requeue)
@@ -886,9 +864,9 @@ out_unlock:
if (hb1 != hb2)
spin_unlock(&hb2->lock);
- /* drop_key_refs() must be called outside the spinlocks. */
+ /* drop_futex_key_refs() must be called outside the spinlocks. */
while (--drop_count >= 0)
- drop_key_refs(&key1);
+ drop_futex_key_refs(&key1);
out:
up_read(&current->mm->mmap_sem);
@@ -906,7 +884,7 @@ queue_lock(struct futex_q *q, int fd, struct file *filp)
init_waitqueue_head(&q->waiters);
- get_key_refs(&q->key);
+ get_futex_key_refs(&q->key);
hb = hash_futex(&q->key);
q->lock_ptr = &hb->lock;
@@ -925,7 +903,7 @@ static inline void
queue_unlock(struct futex_q *q, struct futex_hash_bucket *hb)
{
spin_unlock(&hb->lock);
- drop_key_refs(&q->key);
+ drop_futex_key_refs(&q->key);
}
/*
@@ -980,7 +958,7 @@ static int unqueue_me(struct futex_q *q)
ret = 1;
}
- drop_key_refs(&q->key);
+ drop_futex_key_refs(&q->key);
return ret;
}
@@ -999,15 +977,18 @@ static void unqueue_me_pi(struct futex_q *q, struct futex_hash_bucket *hb)
spin_unlock(&hb->lock);
- drop_key_refs(&q->key);
+ drop_futex_key_refs(&q->key);
}
-static int futex_wait(u32 __user *uaddr, u32 val, unsigned long time)
+static long futex_wait_restart(struct restart_block *restart);
+static int futex_wait_abstime(u32 __user *uaddr, u32 val,
+ int timed, unsigned long abs_time)
{
struct task_struct *curr = current;
DECLARE_WAITQUEUE(wait, curr);
struct futex_hash_bucket *hb;
struct futex_q q;
+ unsigned long time_left = 0;
u32 uval;
int ret;
@@ -1087,8 +1068,21 @@ static int futex_wait(u32 __user *uaddr, u32 val, unsigned long time)
* !list_empty() is safe here without any lock.
* q.lock_ptr != 0 is not safe, because of ordering against wakeup.
*/
- if (likely(!list_empty(&q.list)))
- time = schedule_timeout(time);
+ time_left = 0;
+ if (likely(!list_empty(&q.list))) {
+ unsigned long rel_time;
+
+ if (timed) {
+ unsigned long now = jiffies;
+ if (time_after(now, abs_time))
+ rel_time = 0;
+ else
+ rel_time = abs_time - now;
+ } else
+ rel_time = MAX_SCHEDULE_TIMEOUT;
+
+ time_left = schedule_timeout(rel_time);
+ }
__set_current_state(TASK_RUNNING);
/*
@@ -1099,13 +1093,25 @@ static int futex_wait(u32 __user *uaddr, u32 val, unsigned long time)
/* If we were woken (and unqueued), we succeeded, whatever. */
if (!unqueue_me(&q))
return 0;
- if (time == 0)
+ if (time_left == 0)
return -ETIMEDOUT;
+
/*
* We expect signal_pending(current), but another thread may
* have handled it for us already.
*/
- return -EINTR;
+ if (time_left == MAX_SCHEDULE_TIMEOUT)
+ return -ERESTARTSYS;
+ else {
+ struct restart_block *restart;
+ restart = &current_thread_info()->restart_block;
+ restart->fn = futex_wait_restart;
+ restart->arg0 = (unsigned long)uaddr;
+ restart->arg1 = (unsigned long)val;
+ restart->arg2 = (unsigned long)timed;
+ restart->arg3 = abs_time;
+ return -ERESTART_RESTARTBLOCK;
+ }
out_unlock_release_sem:
queue_unlock(&q, hb);
@@ -1115,6 +1121,24 @@ static int futex_wait(u32 __user *uaddr, u32 val, unsigned long time)
return ret;
}
+static int futex_wait(u32 __user *uaddr, u32 val, unsigned long rel_time)
+{
+ int timed = (rel_time != MAX_SCHEDULE_TIMEOUT);
+ return futex_wait_abstime(uaddr, val, timed, jiffies+rel_time);
+}
+
+static long futex_wait_restart(struct restart_block *restart)
+{
+ u32 __user *uaddr = (u32 __user *)restart->arg0;
+ u32 val = (u32)restart->arg1;
+ int timed = (int)restart->arg2;
+ unsigned long abs_time = restart->arg3;
+
+ restart->fn = do_no_restart_syscall;
+ return (long)futex_wait_abstime(uaddr, val, timed, abs_time);
+}
+
+
/*
* Userspace tried a 0 -> TID atomic transition of the futex value
* and failed. The kernel side here does the whole locking operation:
generated by cgit v1.2.3 (git 2.25.1) at 2024-08-15 23:17:40 +0000