[PATCH 2/6] futex: factor out the futex wake handling

[Jens Axboe <axboe@kernel.dk>]

In preparation for having another waker that isn't futex_wake_mark(),
add a wake handler in futex_q and rename the futex_q->task field to just
be wake_data. futex_wake_mark() is defined as the standard wakeup helper.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 kernel/futex/core.c     | 2 +-
 kernel/futex/futex.h    | 3 ++-
 kernel/futex/requeue.c  | 7 ++++---
 kernel/futex/waitwake.c | 8 ++++----
 4 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/kernel/futex/core.c b/kernel/futex/core.c
index 514e4582b863..6223cce3d876 100644
--- a/kernel/futex/core.c
+++ b/kernel/futex/core.c
@@ -556,7 +556,7 @@ void __futex_queue(struct futex_q *q, struct futex_hash_bucket *hb)
 
 	plist_node_init(&q->list, prio);
 	plist_add(&q->list, &hb->chain);
-	q->task = current;
+	q->wake_data = current;
 }
 
 /**
diff --git a/kernel/futex/futex.h b/kernel/futex/futex.h
index d2949fca37d1..1b7dd5266dd2 100644
--- a/kernel/futex/futex.h
+++ b/kernel/futex/futex.h
@@ -96,7 +96,6 @@ struct futex_pi_state {
 struct futex_q {
 	struct plist_node list;
 
-	struct task_struct *task;
 	spinlock_t *lock_ptr;
 	union futex_key key;
 	struct futex_pi_state *pi_state;
@@ -107,6 +106,8 @@ struct futex_q {
 #ifdef CONFIG_PREEMPT_RT
 	struct rcuwait requeue_wait;
 #endif
+	void (*wake)(struct wake_q_head *wake_q, struct futex_q *);
+	void *wake_data;
 } __randomize_layout;
 
 extern const struct futex_q futex_q_init;
diff --git a/kernel/futex/requeue.c b/kernel/futex/requeue.c
index cba8b1a6a4cc..6aee8408c341 100644
--- a/kernel/futex/requeue.c
+++ b/kernel/futex/requeue.c
@@ -61,6 +61,7 @@ const struct futex_q futex_q_init = {
 	.key		= FUTEX_KEY_INIT,
 	.bitset		= FUTEX_BITSET_MATCH_ANY,
 	.requeue_state	= ATOMIC_INIT(Q_REQUEUE_PI_NONE),
+	.wake		= futex_wake_mark,
 };
 
 /**
@@ -234,7 +235,7 @@ void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key,
 
 	/* Signal locked state to the waiter */
 	futex_requeue_pi_complete(q, 1);
-	wake_up_state(q->task, TASK_NORMAL);
+	wake_up_state(q->wake_data, TASK_NORMAL);
 }
 
 /**
@@ -316,7 +317,7 @@ futex_proxy_trylock_atomic(u32 __user *pifutex, struct futex_hash_bucket *hb1,
 	 * the user space lock can be acquired then PI state is attached to
 	 * the new owner (@top_waiter->task) when @set_waiters is true.
 	 */
-	ret = futex_lock_pi_atomic(pifutex, hb2, key2, ps, top_waiter->task,
+	ret = futex_lock_pi_atomic(pifutex, hb2, key2, ps, top_waiter->wake_data,
 				   exiting, set_waiters);
 	if (ret == 1) {
 		/*
@@ -626,7 +627,7 @@ int futex_requeue(u32 __user *uaddr1, unsigned int flags, u32 __user *uaddr2,
 
 		ret = rt_mutex_start_proxy_lock(&pi_state->pi_mutex,
 						this->rt_waiter,
-						this->task);
+						this->wake_data);
 
 		if (ret == 1) {
 			/*
diff --git a/kernel/futex/waitwake.c b/kernel/futex/waitwake.c
index ba01b9408203..5151c83e2db8 100644
--- a/kernel/futex/waitwake.c
+++ b/kernel/futex/waitwake.c
@@ -114,7 +114,7 @@
  */
 void futex_wake_mark(struct wake_q_head *wake_q, struct futex_q *q)
 {
-	struct task_struct *p = q->task;
+	struct task_struct *p = q->wake_data;
 
 	if (WARN(q->pi_state || q->rt_waiter, "refusing to wake PI futex\n"))
 		return;
@@ -174,7 +174,7 @@ int futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset)
 			if (!(this->bitset & bitset))
 				continue;
 
-			futex_wake_mark(&wake_q, this);
+			this->wake(&wake_q, this);
 			if (++ret >= nr_wake)
 				break;
 		}
@@ -289,7 +289,7 @@ int futex_wake_op(u32 __user *uaddr1, unsigned int flags, u32 __user *uaddr2,
 				ret = -EINVAL;
 				goto out_unlock;
 			}
-			futex_wake_mark(&wake_q, this);
+			this->wake(&wake_q, this);
 			if (++ret >= nr_wake)
 				break;
 		}
@@ -303,7 +303,7 @@ int futex_wake_op(u32 __user *uaddr1, unsigned int flags, u32 __user *uaddr2,
 					ret = -EINVAL;
 					goto out_unlock;
 				}
-				futex_wake_mark(&wake_q, this);
+				this->wake(&wake_q, this);
 				if (++op_ret >= nr_wake2)
 					break;
 			}
-- 
2.39.2