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Commit dfe96ddc authored by Daniel Vetter's avatar Daniel Vetter Committed by Rob Clark
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omapdrm: simplify locking in the fb debugfs file 



We don't need to hold onto mode_config.mutex any more to keep the fb
objects around. And locking dev->struct_mutex is also not required,
since omap_gem_describe only reads data anyway. And for a debug
interface it's better to grab fewer locks in case the driver is
deadlocked already ...

The only thing we need is to hold onto mode_config.fb_lock to ensure
the user-created fbs don't disappear. The fbcon fb doesn't need any
protection, since it lives as long as the driver (and so the debugfs
files) itself. And if the teardown/setup isn't following the right
sequence grabbing locks won't prevent a NULL deref on priv->fbdev if
the fb is not yet (or no longer) there.

Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: default avatarRob Clark <robdclark@gmail.com>
parent 16ef3dfe

drivers/gpu/drm/omapdrm/omap_debugfs.c

+0 −14
Original line number Diff line number Diff line
@@ -57,17 +57,6 @@ static int fb_show(struct seq_file *m, void *arg) 
	struct drm_device *dev = node->minor->dev;

	struct omap_drm_private *priv = dev->dev_private;

	struct drm_framebuffer *fb;

	int ret;



	ret = mutex_lock_interruptible(&dev->mode_config.mutex);

	if (ret)

		return ret;



	ret = mutex_lock_interruptible(&dev->struct_mutex);

	if (ret) {

		mutex_unlock(&dev->mode_config.mutex);

		return ret;

	}



	seq_printf(m, "fbcon ");

	omap_framebuffer_describe(priv->fbdev->fb, m);
@@ -82,9 +71,6 @@ static int fb_show(struct seq_file *m, void *arg) 
	}

	mutex_unlock(&dev->mode_config.fb_lock);



	mutex_unlock(&dev->struct_mutex);

	mutex_unlock(&dev->mode_config.mutex);



	return 0;

}