Re: [RFC/RFT 1/5] Input: implement proper locking in input core

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Dmitry Torokhov wrote:
+static void input_repeat_key(unsigned long data)
+{
+	struct input_dev *dev = (void *) data;
- change_bit(code, dev->key);
+	spin_lock_irq(&dev->event_lock);
[...]
+void input_inject_event(struct input_handle *handle,
+			unsigned int type, unsigned int code, int value)
 {
-	struct input_dev *dev = (void *) data;
+	struct input_dev *dev = handle->dev;
+	struct input_handle *grab;
- if (!test_bit(dev->repeat_key, dev->key))
-		return;
+	if (is_event_supported(type, dev->evbit, EV_MAX)) {
+		spin_lock_irq(&dev->event_lock);
- input_event(dev, EV_KEY, dev->repeat_key, 2);
-	input_sync(dev);
+		grab = rcu_dereference(dev->grab);
+		if (!grab || grab == handle)
+			input_handle_event(dev, type, code, value);
- if (dev->rep[REP_PERIOD])
-		mod_timer(&dev->timer, jiffies + msecs_to_jiffies(dev->rep[REP_PERIOD]));
+		spin_unlock_irq(&dev->event_lock);
+	}
 }
+EXPORT_SYMBOL(input_inject_event);
[...]
+	spin_lock_irq(&dev->event_lock);
+
+	/*
+	 * Simulate keyup events for all pressed keys so that handlers
+	 * are not left with "stuck" keys. The driver may continue
+	 * generate events even after we done here but they will not
+	 * reach any handlers.
+	 */
+	if (is_event_supported(EV_KEY, dev->evbit, EV_MAX)) {
+		for (code = 0; code <= KEY_MAX; code++) {
+			if (is_event_supported(code, dev->keybit, KEY_MAX) &&
+			    test_bit(code, dev->key)) {
+				input_pass_event(dev, EV_KEY, code, 0);
+			}
+		}
+		input_pass_event(dev, EV_SYN, SYN_REPORT, 1);
+	}
+
+	list_for_each_entry(handle, &dev->h_list, d_node)
+		handle->open = 0;
+
+	spin_unlock_irq(&dev->event_lock);


spin_lock_irq() should generally be avoided.

In cases like the first case -- input_repeat_key() -- you are making incorrect assumptions about the state of interrupts. The other cases are probably ok, but in general spin_lock_irq() has a long history of being very fragile and quite often wrong.

Use spin_lock_irqsave() to be safe. Definitely in input_repeat_key(), but I strongly recommend removing spin_lock_irq() from all your patches here.

	Jeff


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