linux-kernel - Re: [PATCH 2/3] sysfs: Fix and sysfs_mv_dir by using lock

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Message-Id: <1223414469.31401.18.camel@nimitz>
Date:	Tue, 07 Oct 2008 14:21:09 -0700
From:	Dave Hansen <dave@...ux.vnet.ibm.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	Greg KH <greg@...ah.com>, Al Viro <viro@...IV.linux.org.uk>,
	Benjamin Thery <benjamin.thery@...l.net>,
	linux-kernel@...r.kernel.org, "Serge E. Hallyn" <serue@...ibm.com>,
	Al Viro <viro@....linux.org.uk>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH 2/3] sysfs: Fix and sysfs_mv_dir by using lock_rename.

On Tue, 2008-10-07 at 03:51 -0700, Eric W. Biederman wrote:
> sysfs_mv_dir picks an arbitrary mutex lock ordering and busy waits
> until it can grab the inode mutexes in that order.  This can dead lock
> on UP systems.
> 
> Instead use the generic lock_rename that guarantees we grab parent
> directories before child directories, so there is not need to spin and
> no chance of deadlock.

This is a vast improvement over what was there before.  Nice!

-- Dave

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