From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from imap1.codethink.co.uk ([176.9.8.82]:45810 "EHLO imap1.codethink.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726608AbeIMAA1 (ORCPT ); Wed, 12 Sep 2018 20:00:27 -0400 Message-ID: <1536778472.3024.204.camel@codethink.co.uk> Subject: Re: [PATCH 4.4 18/31] r8152: napi hangup fix after disconnect From: Ben Hutchings To: Jiri Slaby , linux-usb@vger.kernel.org, netdev@vger.kernel.org, "David S. Miller" Cc: stable@vger.kernel.org, Greg Kroah-Hartman , LKML Date: Wed, 12 Sep 2018 19:54:32 +0100 In-Reply-To: <3b118091-d600-0be8-3204-c0f794ef6288@suse.cz> References: <20180720121340.158484922@linuxfoundation.org> <20180720121340.812996969@linuxfoundation.org> <1535128726.2902.32.camel@codethink.co.uk> <3b118091-d600-0be8-3204-c0f794ef6288@suse.cz> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: On Sat, 2018-08-25 at 09:43 +0200, Jiri Slaby wrote: > On 08/24/2018, 06:38 PM, Ben Hutchings wrote: > > On Fri, 2018-07-20 at 14:13 +0200, Greg Kroah-Hartman wrote: > > > 4.4-stable review patch.  If anyone has any objections, please let me know. > > > > > > ------------------ > > > > > > From: Jiri Slaby > > > > > > [ Upstream commit 0ee1f4734967af8321ecebaf9c74221ace34f2d5 ] > > > > [...] > > > --- a/drivers/net/usb/r8152.c > > > +++ b/drivers/net/usb/r8152.c > > > @@ -3139,7 +3139,8 @@ static int rtl8152_close(struct net_devi > > >  #ifdef CONFIG_PM_SLEEP > > >   unregister_pm_notifier(&tp->pm_notifier); > > >  #endif > > > - napi_disable(&tp->napi); > > > + if (!test_bit(RTL8152_UNPLUG, &tp->flags)) > > > + napi_disable(&tp->napi); > > >   clear_bit(WORK_ENABLE, &tp->flags); > > >   usb_kill_urb(tp->intr_urb); > > >   cancel_delayed_work_sync(&tp->schedule); > > > > This flag appears to be set only if the USB device is actually > > disconnected.  In case the driver is unbound for some other reason > > (like the module is removed), the same problem will occur. > > Could you elaborate? I thought this would happen: > module_exit -> usb_deregister -> usb_unbind_device -> rtl8152_disconnect > -> unregister_netdev -> rtl8152_close > > Am I missing something? What I mean is that if the USB device has not been *physically* disconnected then its usb_device::state will not be USB_STATE_NOTATTACHED. So rtl8152_disconnect() will not set the RTL8152_UNPLUG flag and rtl8152_close() will still call napi_disable() which will hang. Some options to fix this: - Add a separate flag which rtl8152_close() checks and rtl8152_disconnect() always sets - Call dev_close() before netif_napi_del() Ben. -- Ben Hutchings, Software Developer   Codethink Ltd https://www.codethink.co.uk/ Dale House, 35 Dale Street Manchester, M1 2HF, United Kingdom