lkml.org 
[lkml]   [2007]   [Feb]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Subject[PATCH 2/2] lguest preparation: expose futex infrastructure: get_futex_key, get_key_refs and drop_key_refs
From
Date
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>

===================================================================
--- a/include/linux/futex.h
+++ b/include/linux/futex.h
@@ -100,6 +100,35 @@ extern int
extern int
handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi);

+/*
+ * 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;
+};
+int get_futex_key(u32 __user *uaddr, union futex_key *key);
+void get_futex_key_refs(union futex_key *key);
+void drop_futex_key_refs(union futex_key *key);
+
#ifdef CONFIG_FUTEX
extern void exit_robust_list(struct task_struct *curr);
extern void exit_pi_state_list(struct task_struct *curr);
===================================================================
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -48,37 +48,12 @@
#include <linux/pagemap.h>
#include <linux/syscalls.h>
#include <linux/signal.h>
+#include <linux/module.h>
#include <asm/futex.h>

#include "rtmutex_common.h"

#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:
@@ -175,7 +150,7 @@ static inline int match_futex(union fute
*
* 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 *uad
}
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 *uad
* 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 fu
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_ke
mmdrop(key->private.mm);
}
}
+EXPORT_SYMBOL_GPL(drop_futex_key_refs);

static inline int get_futex_value_locked(u32 *dest, u32 __user *from)
{
@@ -871,7 +849,7 @@ static int futex_requeue(u32 __user *uad
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)
@@ -884,9 +862,9 @@ 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);
@@ -904,7 +882,7 @@ queue_lock(struct futex_q *q, int fd, st

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;

@@ -923,7 +901,7 @@ queue_unlock(struct futex_q *q, struct f
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);
}

/*
@@ -978,7 +956,7 @@ static int unqueue_me(struct futex_q *q)
ret = 1;
}

- drop_key_refs(&q->key);
+ drop_futex_key_refs(&q->key);
return ret;
}

@@ -997,7 +975,7 @@ static void unqueue_me_pi(struct futex_q

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)


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-02-12 04:51    [from the cache]
©2003-2011 Jasper Spaans