From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lino Sanfilippo Subject: Re: [PATCH net 2/2] cxgb4: Disable interrupts and napi before unregistering netdev Date: Sat, 28 Mar 2015 05:20:37 +0100 Message-ID: <55162C15.1000807@gmx.de> References: <1427344466-17658-1-git-send-email-hariprasad@chelsio.com> <1427344466-17658-3-git-send-email-hariprasad@chelsio.com> <551473D6.2050406@gmx.de> <20150327085447.GA20708@hariprasad-pc.asicdesigners.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, davem@davemloft.net, leedom@chelsio.com, anish@chelsio.com, nirranjan@chelsio.com, kumaras@chelsio.com, swise@opengridcomputing.com To: Hariprasad S Return-path: Received: from mout.gmx.net ([212.227.15.15]:65313 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750842AbbC1EUq (ORCPT ); Sat, 28 Mar 2015 00:20:46 -0400 In-Reply-To: <20150327085447.GA20708@hariprasad-pc.asicdesigners.com> Sender: netdev-owner@vger.kernel.org List-ID: On 27.03.2015 09:54, Hariprasad S wrote: >> >> just out of curiousity: How can an unregister of a netdevice lead to a >> crash caused by traffic? I understand that _freeing_ the device or other >> resources is a bad idea as long as irqs are still active. But unregister >> should not do anything critical (i am asking since I want to avoid such >> problems in my own drivers). >> >> Regards, >> Lino >> > > When device is unregistered ip_ptr of net_device structure is set to NULL. > Since NAPI is not disabled, every packet goes through ip_error() check. > And in ip_error() function when in_device structure is obtained from netdevice > structure, it ends up in NULL pointer dereference since ip_ptr is already NULL. > > Regards, > Hari > Ah ok, that makes sense. I missed the cleanup done due to netdev notifier calls (in this case ip_netdev_notifier). Thanks for pointing this out. Regards, Lino