Commit b6875734 authored Sep 08, 2014 by Tejun Heo Committed by Jens Axboe Sep 08, 2014

bdi: remove bdi->wb_lock locking around bdi->dev clearing in bdi_unregister()



The only places where NULL test on bdi->dev is used are
bdi_[un]register().  The functions can't be called in parallel anyway
and there's no point in protecting bdi->dev clearing with a lock.
Remove bdi->wb_lock grabbing around bdi->dev clearing and move it
after device_unregister() call so that bdi->dev doesn't have to be
cached in a local variable.

This patch shouldn't introduce any behavior difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>

parent e36f1dfc

mm/backing-dev.c

+2 −8

Original line number	Diff line number	Diff line
		@@ -402,21 +402,15 @@ static void bdi_prune_sb(struct backing_dev_info *bdi)

		void bdi_unregister(struct backing_dev_info *bdi)
		{
		struct device *dev = bdi->dev;

		if (dev) {
		if (bdi->dev) {
		bdi_set_min_ratio(bdi, 0);
		trace_writeback_bdi_unregister(bdi);
		bdi_prune_sb(bdi);

		bdi_wb_shutdown(bdi);
		bdi_debug_unregister(bdi);

		spin_lock_bh(&bdi->wb_lock);
		device_unregister(bdi->dev);
		bdi->dev = NULL;
		spin_unlock_bh(&bdi->wb_lock);

		device_unregister(dev);
		}
		}
		EXPORT_SYMBOL(bdi_unregister);