From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: Broken link in /sys/class/net/ [was: [GIT] Networking] Date: Sat, 29 Oct 2011 21:49:47 -0700 Message-ID: References: <20111025.063206.2273357152859701628.davem@davemloft.net> <20111025131315.GA1899@suse.de> <4EAC8642.3050309@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Greg KH , Linus Torvalds , David Miller , Mikulas Patocka , akpm@linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Jiri Slaby To: Jiri Slaby Return-path: In-Reply-To: <4EAC8642.3050309@suse.cz> (Jiri Slaby's message of "Sun, 30 Oct 2011 01:03:30 +0200") Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Jiri Slaby writes: > On 10/25/2011 03:13 PM, Greg KH wrote: >> On Tue, Oct 25, 2011 at 01:46:11PM +0200, Linus Torvalds wrote: >>> Anyway, after that rant about really bad practices, let me say that I >>> did fix up the conflict and I think it's right. But I won't guarantee >>> it, so please check the changes to fs/sysfs/dir.c. >> >> I think it looks ok, I've booted the merge result, and am typing and >> sending this from the new kernel, and it hasn't crashed yet :) > > Hi, maybe this was not caused by the merge, but the patch[1] causes this > mess in /sys/class/net/ for me: > l????????? ? ? ? ? ? eth1 > > This happens after one renames a net device -- the new name is eth1 here. > > [1] 4f72c0cab40 (sysfs: use rb-tree for name lookups) This looks pretty fixable but today sysfs_rename does not do anything with the to move a renamed entry to a different position in the rbtree. If the directory itself changes sysfs_rename should be fine, and it looks like a trivial patch to always apply the directory rename logic in sysfs_rename. I think all we need is something like the untested patch below to fix the network device rename problem. Eric diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index 48ffbdf..a294068 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -865,14 +865,13 @@ int sysfs_rename(struct sysfs_dirent *sd, sd->s_name = new_name; } - /* Remove from old parent's list and insert into new parent's list. */ - if (sd->s_parent != new_parent_sd) { - sysfs_unlink_sibling(sd); - sysfs_get(new_parent_sd); - sysfs_put(sd->s_parent); - sd->s_parent = new_parent_sd; - sysfs_link_sibling(sd); - } + /* Move to the appropriate place in the appropriate directories rbtree. */ + sysfs_unlink_sibling(sd); + sysfs_get(new_parent_sd); + sysfs_put(sd->s_parent); + sd->s_parent = new_parent_sd; + sysfs_link_sibling(sd); + sd->s_ns = new_ns; error = 0;