linux-kernel - Re: [Bug] INFO: task hung in hub

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <416a8311-c725-419a-8b22-74c80207347f@rowland.harvard.edu>
Date: Mon, 4 Mar 2024 13:30:35 -0500
From: Alan Stern <stern@...land.harvard.edu>
To: Greg KH <gregkh@...uxfoundation.org>
Cc: Sam Sun <samsun1006219@...il.com>, Tejun Heo <tj@...nel.org>,
  linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
  "xrivendell7@...il.com" <xrivendell7@...il.com>, hgajjar@...adit-jv.com,
  quic_ugoswami@...cinc.com, stanley_chang@...ltek.com,
  heikki.krogerus@...ux.intel.com
Subject: Re: [Bug] INFO: task hung in hub_activate

On Mon, Mar 04, 2024 at 05:36:19PM +0100, Greg KH wrote:
> On Mon, Mar 04, 2024 at 11:15:24AM -0500, Alan Stern wrote:
> > Third, this must be a generic problem.  It will occur any time a sysfs
> > attribute callback tries to lock its device while another process is
> > trying to unregister that device.
> > 
> > We faced this sort of problem some years ago when we were worrying
> > about "suicidal" attributes -- ones which would unregister their own
> > devices.  I don't remember what the fix was or how it worked.  But we
> > need something like it here.
> > 
> > Greg and Tejun, any ideas?  Is it possible somehow for an attribute file 
> > to be removed while its callback is still running?
> 
> Yes, it's a pain, and I hate it, but I think SCSI does this somehow for
> one of their attributes.  I don't remember how at the moment, and I
> can't look it up (am traveling), but this should be a good hint.

Are you thinking of the sysfs_break_active_protection() and 
sysfs_unbreak_active_protection() functions?  They seem to be the 
appropriate ones to use here.

Alan Stern