[PATCH] Futex update IV: use a waitqueue.

This turns the simple task pointer into a waitqueue, which is
needed for the poll() patch.

diff --git a/kernel/futex.c b/kernel/futex.c
index a91d8ee276a40942d42cbf2b8084e16a7c173ffc..bdff307969efacdfa63cc7c7eaf166fcd9ddf78e 100644 (file)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -45,7 +45,7 @@
    the relevent ones (hashed queues may be shared) */
 struct futex_q {
        struct list_head list;
-       struct task_struct *task;
+       wait_queue_head_t waiters;
        /* Page struct and offset within it. */
        struct page *page;
        unsigned int offset;
@@ -65,6 +65,11 @@ static inline struct list_head *hash_futex(struct page *page,
        return &futex_queues[hash_long(h, FUTEX_HASHBITS)];
 }
 
+static inline void tell_waiter(struct futex_q *q)
+{
+       wake_up_all(&q->waiters);
+}
+
 static int futex_wake(struct list_head *head,
                      struct page *page,
                      unsigned int offset,
@@ -79,7 +84,7 @@ static int futex_wake(struct list_head *head,
 
                if (this->page == page && this->offset == offset) {
                        list_del_init(i);
-                       wake_up_process(this->task);
+                       tell_waiter(this);
                        num_woken++;
                        if (num_woken >= num) break;
                }
@@ -90,11 +95,12 @@ static int futex_wake(struct list_head *head,
 
 /* Add at end to avoid starvation */
 static inline void queue_me(struct list_head *head,
+                           wait_queue_t *wait,
                            struct futex_q *q,
                            struct page *page,
                            unsigned int offset)
 {
-       q->task = current;
+       add_wait_queue(&q->waiters, wait);
        q->page = page;
        q->offset = offset;
 
@@ -146,10 +152,11 @@ static int futex_wait(struct list_head *head,
 {
        int curval;
        struct futex_q q;
+       DECLARE_WAITQUEUE(wait, current);
        int ret = 0;
 
        set_current_state(TASK_INTERRUPTIBLE);
-       queue_me(head, &q, page, offset);
+       queue_me(head, &wait, &q, page, offset);
 
        /* Page is pinned, but may no longer be in this address space. */
        if (get_user(curval, uaddr) != 0) {