drm: Serialise multiple event readers (9b2c0b7f) · Commits · 戴 / test

drivers/gpu/drm/drm_fops.c

+13 −5

Original line number	Diff line number	Diff line
		@@ -172,6 +172,8 @@ static int drm_open_helper(struct file filp, struct drm_minor minor)
		init_waitqueue_head(&priv->event_wait);
		priv->event_space = 4096; /* set aside 4k for event buffer */

		mutex_init(&priv->event_read_lock);

		if (drm_core_check_feature(dev, DRIVER_GEM))
		drm_gem_open(dev, priv);

		@@ -483,11 +485,15 @@ ssize_t drm_read(struct file filp, char __user buffer,
		{
		struct drm_file *file_priv = filp->private_data;
		struct drm_device *dev = file_priv->minor->dev;
		ssize_t ret = 0;
		ssize_t ret;

		if (!access_ok(VERIFY_WRITE, buffer, count))
		return -EFAULT;

		ret = mutex_lock_interruptible(&file_priv->event_read_lock);
		if (ret)
		return ret;

		for (;;) {
		struct drm_pending_event *e = NULL;

		@@ -509,12 +515,13 @@ ssize_t drm_read(struct file filp, char __user buffer,
		break;
		}

		mutex_unlock(&file_priv->event_read_lock);
		ret = wait_event_interruptible(file_priv->event_wait,
		!list_empty(&file_priv->event_list));
		if (ret < 0)
		break;

		ret = 0;
		if (ret >= 0)
		ret = mutex_lock_interruptible(&file_priv->event_read_lock);
		if (ret)
		return ret;
		} else {
		unsigned length = e->event->length;

		@@ -537,6 +544,7 @@ put_back_event:
		e->destroy(e);
		}
		}
		mutex_unlock(&file_priv->event_read_lock);

		return ret;
		}

+2 −0

Original line number	Diff line number	Diff line
		@@ -344,6 +344,8 @@ struct drm_file {
		struct list_head event_list;
		int event_space;

		struct mutex event_read_lock;

		struct drm_prime_file_private prime;
		};