Commit 19051c50 authored May 15, 2008 by Greg Kroah-Hartman

mm: bdi: fix race in bdi_class device creation



There is a race from when a device is created with device_create() and
then the drvdata is set with a call to dev_set_drvdata() in which a
sysfs file could be open, yet the drvdata will be NULL, causing all
sorts of bad things to happen.

This patch fixes the problem by using the new function,
device_create_vargs().

Many thanks to Arthur Jones <ajones@riverbed.com> for reporting the bug,
and testing patches out.

Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Arthur Jones <ajones@riverbed.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

parent 8882b394

mm/backing-dev.c

+2 −10

Original line number	Diff line number	Diff line
		@@ -172,30 +172,22 @@ postcore_initcall(bdi_class_init);
		int bdi_register(struct backing_dev_info bdi, struct device parent,
		const char *fmt, ...)
		{
		char *name;
		va_list args;
		int ret = 0;
		struct device *dev;

		va_start(args, fmt);
		name = kvasprintf(GFP_KERNEL, fmt, args);
		dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args);
		va_end(args);

		if (!name)
		return -ENOMEM;

		dev = device_create(bdi_class, parent, MKDEV(0, 0), name);
		if (IS_ERR(dev)) {
		ret = PTR_ERR(dev);
		goto exit;
		}

		bdi->dev = dev;
		dev_set_drvdata(bdi->dev, bdi);
		bdi_debug_register(bdi, name);
		bdi_debug_register(bdi, dev_name(dev));

		exit:
		kfree(name);
		return ret;
		}
		EXPORT_SYMBOL(bdi_register);