Re: problem with kthread changes that went into cifs_demultiplex_thread

[Jeff Layton <jlayton@redhat.com>]

On Tue, 10 Jun 2008 10:41:29 -0500
"Steve French" <smfrench@gmail.com> wrote:

> In working on the smb2 client implementation, I noticed that there is
> a problem with the revised kthread logic which takes down cifsd
> (cifs_demultiplex_thread) on umount or on abnormal socket termination
> during protocol negotiation.    I noticed this while looking at SMB2
> since the Samba 4 SMB2 server was not handling the new SMB2 Negotiate
> protocol request (and unlike Windows Server 2008) and was closing the
> tcp session immediately after receiving the negprot request from the
> client.  An unexpected error on negprot which causes the TCP session
> to close will cause cifsd to exit, but now  this blocks forever at
> kthread_should_stop just after the main loop in
> cifs_demultiplex_thread. 

Ok, I think I see what you're talking about. *sigh* -- and I just posted
the patch to make the kthread go to sleep to our internal mailing lists
this morning.

> The task doing mount is blocked in
> wait_event on the response_q but will never be woken up by cifsd (even
> though it would timeout if some one did wake it up once the 15 second
> timeout was expired).   umount will never call kthread_stop because
> mount never succeeded - we do not have a tree connection yet (so tcon
> is null and we can't get to tcon->ses->server) and the failed mount
> won't call kthread_stop because it is stuck in wait_event with no one
> to wake up response_q.
> 
> Adding a call to wake_up_all(&server->response_q) right after we set
> server->tcpStatus = CifsExiting at the end of the loop in
> cifs_demultiplex_thread but before we wait for kthread_stop works in
> my testing.
> 

The solution sounds reasonable at first glance. Will you be pushing a
patch to your git tree for this soon?

Thanks,
-- 
Jeff Layton <jlayton@redhat.com>