futex: get_futex_key, get_key_refs and drop_key_refs
lguest uses the convenient futex infrastructure for inter-domain I/O, so
expose get_futex_key, get_key_refs (renamed get_futex_key_refs) and
drop_key_refs (renamed drop_futex_key_refs). Also means we need to expose the
union that these use.
No code changes.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
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 5a270b5..7ae2f50 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 @@
*
* Should be called with ¤t->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 @@
}
return err;
}
+EXPORT_SYMBOL_GPL(get_futex_key);
/*
* Take a reference to the resource addressed by a key.
@@ -254,7 +230,7 @@
* 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 @@
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 @@
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 @@
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 @@
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(¤t->mm->mmap_sem);
@@ -906,7 +884,7 @@
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 @@
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 @@
ret = 1;
}
- drop_key_refs(&q->key);
+ drop_futex_key_refs(&q->key);
return ret;
}
@@ -999,7 +977,7 @@
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)