futex: Create hb scopes

Create explicit scopes for hb variables; almost pure re-indent.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: Peter Zijlstra

kernel/futex/core.c

@@ -944,7 +944,6 @@ static void exit_pi_state_list(struct task_struct *curr)
 {
 	struct list_head *next, *head = &curr->pi_state_list;
 	struct futex_pi_state *pi_state;
-	struct futex_hash_bucket *hb;
 	union futex_key key = FUTEX_KEY_INIT;
 
 	/*
@@ -957,50 +956,54 @@ static void exit_pi_state_list(struct task_struct *curr)
 		next = head->next;
 		pi_state = list_entry(next, struct futex_pi_state, list);
 		key = pi_state->key;
-		hb = futex_hash(&key);
-
-		/*
-		 * We can race against put_pi_state() removing itself from the
-		 * list (a waiter going away). put_pi_state() will first
-		 * decrement the reference count and then modify the list, so
-		 * its possible to see the list entry but fail this reference
-		 * acquire.
-		 *
-		 * In that case; drop the locks to let put_pi_state() make
-		 * progress and retry the loop.
-		 */
-		if (!refcount_inc_not_zero(&pi_state->refcount)) {
+		if (1) {
+			struct futex_hash_bucket *hb;
+
+			hb = futex_hash(&key);
+
+			/*
+			 * We can race against put_pi_state() removing itself from the
+			 * list (a waiter going away). put_pi_state() will first
+			 * decrement the reference count and then modify the list, so
+			 * its possible to see the list entry but fail this reference
+			 * acquire.
+			 *
+			 * In that case; drop the locks to let put_pi_state() make
+			 * progress and retry the loop.
+			 */
+			if (!refcount_inc_not_zero(&pi_state->refcount)) {
+				raw_spin_unlock_irq(&curr->pi_lock);
+				cpu_relax();
+				raw_spin_lock_irq(&curr->pi_lock);
+				continue;
+			}
 			raw_spin_unlock_irq(&curr->pi_lock);
-			cpu_relax();
-			raw_spin_lock_irq(&curr->pi_lock);
-			continue;
-		}
-		raw_spin_unlock_irq(&curr->pi_lock);
 
-		spin_lock(&hb->lock);
-		raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
-		raw_spin_lock(&curr->pi_lock);
-		/*
-		 * We dropped the pi-lock, so re-check whether this
-		 * task still owns the PI-state:
-		 */
-		if (head->next != next) {
-			/* retain curr->pi_lock for the loop invariant */
-			raw_spin_unlock(&pi_state->pi_mutex.wait_lock);
+			spin_lock(&hb->lock);
+			raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
+			raw_spin_lock(&curr->pi_lock);
+			/*
+			 * We dropped the pi-lock, so re-check whether this
+			 * task still owns the PI-state:
+			 */
+			if (head->next != next) {
+				/* retain curr->pi_lock for the loop invariant */
+				raw_spin_unlock(&pi_state->pi_mutex.wait_lock);
+				spin_unlock(&hb->lock);
+				put_pi_state(pi_state);
+				continue;
+			}
+
+			WARN_ON(pi_state->owner != curr);
+			WARN_ON(list_empty(&pi_state->list));
+			list_del_init(&pi_state->list);
+			pi_state->owner = NULL;
+
+			raw_spin_unlock(&curr->pi_lock);
+			raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
 			spin_unlock(&hb->lock);
-			put_pi_state(pi_state);
-			continue;
 		}
 
-		WARN_ON(pi_state->owner != curr);
-		WARN_ON(list_empty(&pi_state->list));
-		list_del_init(&pi_state->list);
-		pi_state->owner = NULL;
-
-		raw_spin_unlock(&curr->pi_lock);
-		raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
-		spin_unlock(&hb->lock);
-
 		rt_mutex_futex_unlock(&pi_state->pi_mutex);
 		put_pi_state(pi_state);