linux-kernel - Re: [PATCH] base firmware: Fix BUG from sysfs attributes change in commit a2db6842873c8e5a70652f278d469128cb52db70

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Date:	Sat, 13 Mar 2010 23:39:35 +0100 (CET)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Larry Finger <Larry.Finger@...inger.net>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	WANG Cong <xiyou.wangcong@...il.com>,
	Greg Kroah-Hartman <gregkh@...e.de>, Tejun Heo <tj@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] base firmware: Fix BUG from sysfs attributes change in
 commit a2db6842873c8e5a70652f278d469128cb52db70

On Sat, 13 Mar 2010, Linus Torvalds wrote:

> > Commit a2db6842873c8e5a70652f278d469128cb52db70 changed the way that
> > sysfs attributes are handled. With lockdep checking enabled, a firmware
> > loading request from b43 generates the following BUG:
> > 
> > BUG: key ffff8800b85f4870 not in .data!
> > ------------[ cut here ]------------
> > WARNING: at kernel/lockdep.c:2706 lockdep_init_map+0x236/0x5d0()
> 
> I don't think we can fix these problems this way.
> 
> Lookie here:
> 
> 	[torvalds@i5 linux]$ git grep sysfs_create_bin_file | wc
> 	     68     319    5999
> 	[torvalds@i5 linux]$ git grep sysfs_bin_attr_init | wc
> 	      8      24     522
> 
> and you sent in patches to fix _two_ of the remaining 60 cases.
>
> Now, there may be some reason why it's not needed for the others, and 
> those two are special, but I somewhat doubt it.

Well, the special initialization shouldn't be needed for all the 68 cases 
as far as I can see. It's needed only for dynamically allocated sysfs 
attributes, the static ones are fine.

> Eric - that patch of yours is obviously broken. Either I need to revert 
> it, or you need to fix it. Not these kinds of "fix random 
> sysfs_create_bin_file() drivers one by one" things.
>
> ---
> > Hardware name: HP Pavilion dv2700 Notebook PC
> > Pid: 2283, comm: NetworkManager Not tainted 2.6.34-rc1-wl #320
> > Call Trace:
> > [<ffffffff81046068>] warn_slowpath_common+0x78/0xb0
> > [<ffffffff810460af>] warn_slowpath_null+0xf/0x20
> > [<ffffffff810765e6>] lockdep_init_map+0x236/0x5d0
> > [<ffffffff811633aa>] sysfs_add_file_mode+0x6a/0xc0
> > [<ffffffff8116340c>] sysfs_add_file+0xc/0x10
> > [<ffffffff81165ae1>] sysfs_create_bin_file+0x21/0x30
> > [<ffffffff8124f6b7>] _request_firmware+0x267/0x630
> > [<ffffffff8124fb0e>] request_firmware+0xe/0x10
> > [<ffffffffa04038d2>] b43_do_request_fw+0x92/0x230 [b43]
> > (rest of dump snipped)
> > 
> > Fixed by initing the attribute.
> > 
> > Signed-off-by: Larry Finger <Larry.Finger@...inger.net>
> > ---
> > 
> > Index: wireless-testing/drivers/base/firmware_class.c
> > ===================================================================
> > --- wireless-testing.orig/drivers/base/firmware_class.c
> > +++ wireless-testing/drivers/base/firmware_class.c
> > @@ -442,6 +442,7 @@ static int fw_setup_device(struct firmwa
> >  	fw_priv = dev_get_drvdata(f_dev);
> >  
> >  	fw_priv->fw = fw;
> > +	sysfs_bin_attr_init(&fw_priv->attr_data);
> >  	retval = sysfs_create_bin_file(&f_dev->kobj, &fw_priv->attr_data);
> >  	if (retval) {
> >  		dev_err(device, "%s: sysfs_create_bin_file failed\n", __func__);
> > 

FWIW, I have submitted this exact patch to Greg a few days ago, and he 
should have it queued already.

-- 
Jiri Kosina
SUSE Labs, Novell Inc.

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