Message-ID: <20241107071538.195340-9-dmitry.torokhov@gmail.com>
Date: Wed,  6 Nov 2024 23:15:35 -0800
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Jiri Kosina <jikos@...nel.org>,
	Benjamin Tissoires <bentiss@...nel.org>,
	Hans de Goede <hdegoede@...hat.com>
Cc: linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 8/8] Input: use guard notation in input core

Switch input core to use "guard" notation when acquiring spinlocks and
mutexes to simplify the code and ensure that locks are automatically
released when control leaves critical section.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
---
 drivers/input/input.c | 339 ++++++++++++++++--------------------------
 1 file changed, 131 insertions(+), 208 deletions(-)

diff --git a/drivers/input/input.c b/drivers/input/input.c
index fd9d40286b75..d73231e695f8 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -115,23 +115,23 @@ static void input_pass_values(struct input_dev *dev,
 
 	lockdep_assert_held(&dev->event_lock);
 
-	rcu_read_lock();
+	scoped_guard(rcu) {
+		handle = rcu_dereference(dev->grab);
+		if (handle) {
+			count = handle->handle_events(handle, vals, count);
+			break;
+		}
 
-	handle = rcu_dereference(dev->grab);
-	if (handle) {
-		count = handle->handle_events(handle, vals, count);
-	} else {
-		list_for_each_entry_rcu(handle, &dev->h_list, d_node)
+		list_for_each_entry_rcu(handle, &dev->h_list, d_node) {
 			if (handle->open) {
 				count = handle->handle_events(handle, vals,
 							      count);
 				if (!count)
 					break;
 			}
+		}
 	}
 
-	rcu_read_unlock();
-
 	/* trigger auto repeat for key events */
 	if (test_bit(EV_REP, dev->evbit) && test_bit(EV_KEY, dev->evbit)) {
 		for (v = vals; v != vals + count; v++) {
@@ -390,13 +390,9 @@ void input_handle_event(struct input_dev *dev,
 void input_event(struct input_dev *dev,
 		 unsigned int type, unsigned int code, int value)
 {
-	unsigned long flags;
-
 	if (is_event_supported(type, dev->evbit, EV_MAX)) {
-
-		spin_lock_irqsave(&dev->event_lock, flags);
+		guard(spinlock_irqsave)(&dev->event_lock);
 		input_handle_event(dev, type, code, value);
-		spin_unlock_irqrestore(&dev->event_lock, flags);
 	}
 }
 EXPORT_SYMBOL(input_event);
@@ -417,18 +413,15 @@ void input_inject_event(struct input_handle *handle,
 {
 	struct input_dev *dev = handle->dev;
 	struct input_handle *grab;
-	unsigned long flags;
 
 	if (is_event_supported(type, dev->evbit, EV_MAX)) {
-		spin_lock_irqsave(&dev->event_lock, flags);
+		guard(spinlock_irqsave)(&dev->event_lock);
+		guard(rcu)();
 
-		rcu_read_lock();
 		grab = rcu_dereference(dev->grab);
 		if (!grab || grab == handle)
 			input_handle_event(dev, type, code, value);
-		rcu_read_unlock();
 
-		spin_unlock_irqrestore(&dev->event_lock, flags);
 	}
 }
 EXPORT_SYMBOL(input_inject_event);
@@ -526,22 +519,15 @@ EXPORT_SYMBOL(input_copy_abs);
 int input_grab_device(struct input_handle *handle)
 {
 	struct input_dev *dev = handle->dev;
-	int retval;
 
-	retval = mutex_lock_interruptible(&dev->mutex);
-	if (retval)
-		return retval;
+	scoped_cond_guard(mutex_intr, return -EINTR, &dev->mutex) {
+		if (dev->grab)
+			return -EBUSY;
 
-	if (dev->grab) {
-		retval = -EBUSY;
-		goto out;
+		rcu_assign_pointer(dev->grab, handle);
 	}
 
-	rcu_assign_pointer(dev->grab, handle);
-
- out:
-	mutex_unlock(&dev->mutex);
-	return retval;
+	return 0;
 }
 EXPORT_SYMBOL(input_grab_device);
 
@@ -576,9 +562,8 @@ void input_release_device(struct input_handle *handle)
 {
 	struct input_dev *dev = handle->dev;
 
-	mutex_lock(&dev->mutex);
+	guard(mutex)(&dev->mutex);
 	__input_release_device(handle);
-	mutex_unlock(&dev->mutex);
 }
 EXPORT_SYMBOL(input_release_device);
 
@@ -592,67 +577,57 @@ EXPORT_SYMBOL(input_release_device);
 int input_open_device(struct input_handle *handle)
 {
 	struct input_dev *dev = handle->dev;
-	int retval;
-
-	retval = mutex_lock_interruptible(&dev->mutex);
-	if (retval)
-		return retval;
-
-	if (dev->going_away) {
-		retval = -ENODEV;
-		goto out;
-	}
+	int error;
 
-	handle->open++;
+	scoped_cond_guard(mutex_intr, return -EINTR, &dev->mutex) {
+		if (dev->going_away)
+			return -ENODEV;
 
-	if (handle->handler->passive_observer)
-		goto out;
+		handle->open++;
 
-	if (dev->users++ || dev->inhibited) {
-		/*
-		 * Device is already opened and/or inhibited,
-		 * so we can exit immediately and report success.
-		 */
-		goto out;
-	}
+		if (handle->handler->passive_observer)
+			return 0;
 
-	if (dev->open) {
-		retval = dev->open(dev);
-		if (retval) {
-			dev->users--;
-			handle->open--;
+		if (dev->users++ || dev->inhibited) {
 			/*
-			 * Make sure we are not delivering any more events
-			 * through this handle
+			 * Device is already opened and/or inhibited,
+			 * so we can exit immediately and report success.
 			 */
-			synchronize_rcu();
-			goto out;
+			return 0;
 		}
-	}
 
-	if (dev->poller)
-		input_dev_poller_start(dev->poller);
+		if (dev->open) {
+			error = dev->open(dev);
+			if (error) {
+				dev->users--;
+				handle->open--;
+				/*
+				 * Make sure we are not delivering any more
+				 * events through this handle.
+				 */
+				synchronize_rcu();
+				return error;
+			}
+		}
 
- out:
-	mutex_unlock(&dev->mutex);
-	return retval;
+		if (dev->poller)
+			input_dev_poller_start(dev->poller);
+	}
+
+	return 0;
 }
 EXPORT_SYMBOL(input_open_device);
 
 int input_flush_device(struct input_handle *handle, struct file *file)
 {
 	struct input_dev *dev = handle->dev;
-	int retval;
 
-	retval = mutex_lock_interruptible(&dev->mutex);
-	if (retval)
-		return retval;
-
-	if (dev->flush)
-		retval = dev->flush(dev, file);
+	scoped_cond_guard(mutex_intr, return -EINTR, &dev->mutex) {
+		if (dev->flush)
+			return dev->flush(dev, file);
+	}
 
-	mutex_unlock(&dev->mutex);
-	return retval;
+	return 0;
 }
 EXPORT_SYMBOL(input_flush_device);
 
@@ -667,7 +642,7 @@ void input_close_device(struct input_handle *handle)
 {
 	struct input_dev *dev = handle->dev;
 
-	mutex_lock(&dev->mutex);
+	guard(mutex)(&dev->mutex);
 
 	__input_release_device(handle);
 
@@ -688,8 +663,6 @@ void input_close_device(struct input_handle *handle)
 		 */
 		synchronize_rcu();
 	}
-
-	mutex_unlock(&dev->mutex);
 }
 EXPORT_SYMBOL(input_close_device);
 
@@ -726,11 +699,10 @@ static void input_disconnect_device(struct input_dev *dev)
 	 * not to protect access to dev->going_away but rather to ensure
 	 * that there are no threads in the middle of input_open_device()
 	 */
-	mutex_lock(&dev->mutex);
-	dev->going_away = true;
-	mutex_unlock(&dev->mutex);
+	scoped_guard(mutex, &dev->mutex)
+		dev->going_away = true;
 
-	spin_lock_irq(&dev->event_lock);
+	guard(spinlock_irq)(&dev->event_lock);
 
 	/*
 	 * Simulate keyup events for all pressed keys so that handlers
@@ -743,8 +715,6 @@ static void input_disconnect_device(struct input_dev *dev)
 
 	list_for_each_entry(handle, &dev->h_list, d_node)
 		handle->open = 0;
-
-	spin_unlock_irq(&dev->event_lock);
 }
 
 /**
@@ -901,14 +871,9 @@ static int input_default_setkeycode(struct input_dev *dev,
  */
 int input_get_keycode(struct input_dev *dev, struct input_keymap_entry *ke)
 {
-	unsigned long flags;
-	int retval;
+	guard(spinlock_irqsave)(&dev->event_lock);
 
-	spin_lock_irqsave(&dev->event_lock, flags);
-	retval = dev->getkeycode(dev, ke);
-	spin_unlock_irqrestore(&dev->event_lock, flags);
-
-	return retval;
+	return dev->getkeycode(dev, ke);
 }
 EXPORT_SYMBOL(input_get_keycode);
 
@@ -923,18 +888,17 @@ EXPORT_SYMBOL(input_get_keycode);
 int input_set_keycode(struct input_dev *dev,
 		      const struct input_keymap_entry *ke)
 {
-	unsigned long flags;
 	unsigned int old_keycode;
-	int retval;
+	int error;
 
 	if (ke->keycode > KEY_MAX)
 		return -EINVAL;
 
-	spin_lock_irqsave(&dev->event_lock, flags);
+	guard(spinlock_irqsave)(&dev->event_lock);
 
-	retval = dev->setkeycode(dev, ke, &old_keycode);
-	if (retval)
-		goto out;
+	error = dev->setkeycode(dev, ke, &old_keycode);
+	if (error)
+		return error;
 
 	/* Make sure KEY_RESERVED did not get enabled. */
 	__clear_bit(KEY_RESERVED, dev->keybit);
@@ -962,10 +926,7 @@ int input_set_keycode(struct input_dev *dev,
 				    EV_SYN, SYN_REPORT, 1);
 	}
 
- out:
-	spin_unlock_irqrestore(&dev->event_lock, flags);
-
-	return retval;
+	return 0;
 }
 EXPORT_SYMBOL(input_set_keycode);
 
@@ -1802,26 +1763,21 @@ static void input_dev_toggle(struct input_dev *dev, bool activate)
  */
 void input_reset_device(struct input_dev *dev)
 {
-	unsigned long flags;
-
-	mutex_lock(&dev->mutex);
-	spin_lock_irqsave(&dev->event_lock, flags);
+	guard(mutex)(&dev->mutex);
+	guard(spinlock_irqsave)(&dev->event_lock);
 
 	input_dev_toggle(dev, true);
 	if (input_dev_release_keys(dev))
 		input_handle_event(dev, EV_SYN, SYN_REPORT, 1);
-
-	spin_unlock_irqrestore(&dev->event_lock, flags);
-	mutex_unlock(&dev->mutex);
 }
 EXPORT_SYMBOL(input_reset_device);
 
 static int input_inhibit_device(struct input_dev *dev)
 {
-	mutex_lock(&dev->mutex);
+	guard(mutex)(&dev->mutex);
 
 	if (dev->inhibited)
-		goto out;
+		return 0;
 
 	if (dev->users) {
 		if (dev->close)
@@ -1830,54 +1786,50 @@ static int input_inhibit_device(struct input_dev *dev)
 			input_dev_poller_stop(dev->poller);
 	}
 
-	spin_lock_irq(&dev->event_lock);
-	input_mt_release_slots(dev);
-	input_dev_release_keys(dev);
-	input_handle_event(dev, EV_SYN, SYN_REPORT, 1);
-	input_dev_toggle(dev, false);
-	spin_unlock_irq(&dev->event_lock);
+	scoped_guard(spinlock_irq, &dev->event_lock) {
+		input_mt_release_slots(dev);
+		input_dev_release_keys(dev);
+		input_handle_event(dev, EV_SYN, SYN_REPORT, 1);
+		input_dev_toggle(dev, false);
+	}
 
 	dev->inhibited = true;
 
-out:
-	mutex_unlock(&dev->mutex);
 	return 0;
 }
 
 static int input_uninhibit_device(struct input_dev *dev)
 {
-	int ret = 0;
+	int error;
 
-	mutex_lock(&dev->mutex);
+	guard(mutex)(&dev->mutex);
 
 	if (!dev->inhibited)
-		goto out;
+		return 0;
 
 	if (dev->users) {
 		if (dev->open) {
-			ret = dev->open(dev);
-			if (ret)
-				goto out;
+			error = dev->open(dev);
+			if (error)
+				return error;
 		}
 		if (dev->poller)
 			input_dev_poller_start(dev->poller);
 	}
 
 	dev->inhibited = false;
-	spin_lock_irq(&dev->event_lock);
-	input_dev_toggle(dev, true);
-	spin_unlock_irq(&dev->event_lock);
 
-out:
-	mutex_unlock(&dev->mutex);
-	return ret;
+	scoped_guard(spinlock_irq, &dev->event_lock)
+		input_dev_toggle(dev, true);
+
+	return 0;
 }
 
 static int input_dev_suspend(struct device *dev)
 {
 	struct input_dev *input_dev = to_input_dev(dev);
 
-	spin_lock_irq(&input_dev->event_lock);
+	guard(spinlock_irq)(&input_dev->event_lock);
 
 	/*
 	 * Keys that are pressed now are unlikely to be
@@ -1889,8 +1841,6 @@ static int input_dev_suspend(struct device *dev)
 	/* Turn off LEDs and sounds, if any are active. */
 	input_dev_toggle(input_dev, false);
 
-	spin_unlock_irq(&input_dev->event_lock);
-
 	return 0;
 }
 
@@ -1898,13 +1848,11 @@ static int input_dev_resume(struct device *dev)
 {
 	struct input_dev *input_dev = to_input_dev(dev);
 
-	spin_lock_irq(&input_dev->event_lock);
+	guard(spinlock_irq)(&input_dev->event_lock);
 
 	/* Restore state of LEDs and sounds, if any were active. */
 	input_dev_toggle(input_dev, true);
 
-	spin_unlock_irq(&input_dev->event_lock);
-
 	return 0;
 }
 
@@ -1912,7 +1860,7 @@ static int input_dev_freeze(struct device *dev)
 {
 	struct input_dev *input_dev = to_input_dev(dev);
 
-	spin_lock_irq(&input_dev->event_lock);
+	guard(spinlock_irq)(&input_dev->event_lock);
 
 	/*
 	 * Keys that are pressed now are unlikely to be
@@ -1921,8 +1869,6 @@ static int input_dev_freeze(struct device *dev)
 	if (input_dev_release_keys(input_dev))
 		input_handle_event(input_dev, EV_SYN, SYN_REPORT, 1);
 
-	spin_unlock_irq(&input_dev->event_lock);
-
 	return 0;
 }
 
@@ -1930,13 +1876,11 @@ static int input_dev_poweroff(struct device *dev)
 {
 	struct input_dev *input_dev = to_input_dev(dev);
 
-	spin_lock_irq(&input_dev->event_lock);
+	guard(spinlock_irq)(&input_dev->event_lock);
 
 	/* Turn off LEDs and sounds, if any are active. */
 	input_dev_toggle(input_dev, false);
 
-	spin_unlock_irq(&input_dev->event_lock);
-
 	return 0;
 }
 
@@ -2277,18 +2221,16 @@ static void __input_unregister_device(struct input_dev *dev)
 
 	input_disconnect_device(dev);
 
-	mutex_lock(&input_mutex);
-
-	list_for_each_entry_safe(handle, next, &dev->h_list, d_node)
-		handle->handler->disconnect(handle);
-	WARN_ON(!list_empty(&dev->h_list));
+	scoped_guard(mutex, &input_mutex) {
+		list_for_each_entry_safe(handle, next, &dev->h_list, d_node)
+			handle->handler->disconnect(handle);
+		WARN_ON(!list_empty(&dev->h_list));
 
-	del_timer_sync(&dev->timer);
-	list_del_init(&dev->node);
+		del_timer_sync(&dev->timer);
+		list_del_init(&dev->node);
 
-	input_wakeup_procfs_readers();
-
-	mutex_unlock(&input_mutex);
+		input_wakeup_procfs_readers();
+	}
 
 	device_del(&dev->dev);
 }
@@ -2311,9 +2253,8 @@ static void devm_input_device_unregister(struct device *dev, void *res)
 static void input_repeat_key(struct timer_list *t)
 {
 	struct input_dev *dev = from_timer(dev, t, timer);
-	unsigned long flags;
 
-	spin_lock_irqsave(&dev->event_lock, flags);
+	guard(spinlock_irqsave)(&dev->event_lock);
 
 	if (!dev->inhibited &&
 	    test_bit(dev->repeat_key, dev->key) &&
@@ -2327,8 +2268,6 @@ static void input_repeat_key(struct timer_list *t)
 			mod_timer(&dev->timer, jiffies +
 					msecs_to_jiffies(dev->rep[REP_PERIOD]));
 	}
-
-	spin_unlock_irqrestore(&dev->event_lock, flags);
 }
 
 /**
@@ -2373,10 +2312,10 @@ static int input_device_tune_vals(struct input_dev *dev)
 	if (!vals)
 		return -ENOMEM;
 
-	spin_lock_irq(&dev->event_lock);
-	dev->max_vals = max_vals;
-	swap(dev->vals, vals);
-	spin_unlock_irq(&dev->event_lock);
+	scoped_guard(spinlock_irq, &dev->event_lock) {
+		dev->max_vals = max_vals;
+		swap(dev->vals, vals);
+	}
 
 	/* Because of swap() above, this frees the old vals memory */
 	kfree(vals);
@@ -2468,18 +2407,15 @@ int input_register_device(struct input_dev *dev)
 		path ? path : "N/A");
 	kfree(path);
 
-	error = mutex_lock_interruptible(&input_mutex);
-	if (error)
-		goto err_device_del;
+	error = -EINTR;
+	scoped_cond_guard(mutex_intr, goto err_device_del, &input_mutex) {
+		list_add_tail(&dev->node, &input_dev_list);
 
-	list_add_tail(&dev->node, &input_dev_list);
+		list_for_each_entry(handler, &input_handler_list, node)
+			input_attach_handler(dev, handler);
 
-	list_for_each_entry(handler, &input_handler_list, node)
-		input_attach_handler(dev, handler);
-
-	input_wakeup_procfs_readers();
-
-	mutex_unlock(&input_mutex);
+		input_wakeup_procfs_readers();
+	}
 
 	if (dev->devres_managed) {
 		dev_dbg(dev->dev.parent, "%s: registering %s with devres.\n",
@@ -2559,20 +2495,17 @@ int input_register_handler(struct input_handler *handler)
 	if (error)
 		return error;
 
-	INIT_LIST_HEAD(&handler->h_list);
+	scoped_cond_guard(mutex_intr, return -EINTR, &input_mutex) {
+		INIT_LIST_HEAD(&handler->h_list);
 
-	error = mutex_lock_interruptible(&input_mutex);
-	if (error)
-		return error;
-
-	list_add_tail(&handler->node, &input_handler_list);
+		list_add_tail(&handler->node, &input_handler_list);
 
-	list_for_each_entry(dev, &input_dev_list, node)
-		input_attach_handler(dev, handler);
+		list_for_each_entry(dev, &input_dev_list, node)
+			input_attach_handler(dev, handler);
 
-	input_wakeup_procfs_readers();
+		input_wakeup_procfs_readers();
+	}
 
-	mutex_unlock(&input_mutex);
 	return 0;
 }
 EXPORT_SYMBOL(input_register_handler);
@@ -2588,7 +2521,7 @@ void input_unregister_handler(struct input_handler *handler)
 {
 	struct input_handle *handle, *next;
 
-	mutex_lock(&input_mutex);
+	guard(mutex)(&input_mutex);
 
 	list_for_each_entry_safe(handle, next, &handler->h_list, h_node)
 		handler->disconnect(handle);
@@ -2597,8 +2530,6 @@ void input_unregister_handler(struct input_handler *handler)
 	list_del_init(&handler->node);
 
 	input_wakeup_procfs_readers();
-
-	mutex_unlock(&input_mutex);
 }
 EXPORT_SYMBOL(input_unregister_handler);
 
@@ -2618,19 +2549,17 @@ int input_handler_for_each_handle(struct input_handler *handler, void *data,
 				  int (*fn)(struct input_handle *, void *))
 {
 	struct input_handle *handle;
-	int retval = 0;
+	int retval;
 
-	rcu_read_lock();
+	guard(rcu)();
 
 	list_for_each_entry_rcu(handle, &handler->h_list, h_node) {
 		retval = fn(handle, data);
 		if (retval)
-			break;
+			return retval;
 	}
 
-	rcu_read_unlock();
-
-	return retval;
+	return 0;
 }
 EXPORT_SYMBOL(input_handler_for_each_handle);
 
@@ -2718,27 +2647,22 @@ int input_register_handle(struct input_handle *handle)
 {
 	struct input_handler *handler = handle->handler;
 	struct input_dev *dev = handle->dev;
-	int error;
 
 	input_handle_setup_event_handler(handle);
 	/*
 	 * We take dev->mutex here to prevent race with
 	 * input_release_device().
 	 */
-	error = mutex_lock_interruptible(&dev->mutex);
-	if (error)
-		return error;
-
-	/*
-	 * Filters go to the head of the list, normal handlers
-	 * to the tail.
-	 */
-	if (handler->filter)
-		list_add_rcu(&handle->d_node, &dev->h_list);
-	else
-		list_add_tail_rcu(&handle->d_node, &dev->h_list);
-
-	mutex_unlock(&dev->mutex);
+	scoped_cond_guard(mutex_intr, return -EINTR, &dev->mutex) {
+		/*
+		 * Filters go to the head of the list, normal handlers
+		 * to the tail.
+		 */
+		if (handler->filter)
+			list_add_rcu(&handle->d_node, &dev->h_list);
+		else
+			list_add_tail_rcu(&handle->d_node, &dev->h_list);
+	}
 
 	/*
 	 * Since we are supposed to be called from ->connect()
@@ -2774,9 +2698,8 @@ void input_unregister_handle(struct input_handle *handle)
 	/*
 	 * Take dev->mutex to prevent race with input_release_device().
 	 */
-	mutex_lock(&dev->mutex);
-	list_del_rcu(&handle->d_node);
-	mutex_unlock(&dev->mutex);
+	scoped_guard(mutex, &dev->mutex)
+		list_del_rcu(&handle->d_node);
 
 	synchronize_rcu();
 }
-- 
2.47.0.277.g8800431eea-goog

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