From owner-freebsd-current@FreeBSD.ORG Mon Oct 19 04:22:37 2009 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 96D0A106566C for ; Mon, 19 Oct 2009 04:22:37 +0000 (UTC) (envelope-from julian@elischer.org) Received: from outW.internet-mail-service.net (outw.internet-mail-service.net [216.240.47.246]) by mx1.freebsd.org (Postfix) with ESMTP id 762EB8FC15 for ; Mon, 19 Oct 2009 04:22:37 +0000 (UTC) Received: from idiom.com (mx0.idiom.com [216.240.32.160]) by out.internet-mail-service.net (Postfix) with ESMTP id 0CD30B755B; Sun, 18 Oct 2009 21:22:37 -0700 (PDT) X-Client-Authorized: MaGic Cook1e X-Client-Authorized: MaGic Cook1e X-Client-Authorized: MaGic Cook1e X-Client-Authorized: MaGic Cook1e Received: from julian-mac.elischer.org (unknown [67.100.89.137]) by idiom.com (Postfix) with ESMTP id 9E8172D6019; Sun, 18 Oct 2009 21:22:36 -0700 (PDT) Message-ID: <4ADBE98C.3030404@elischer.org> Date: Sun, 18 Oct 2009 21:22:36 -0700 From: Julian Elischer User-Agent: Thunderbird 2.0.0.23 (Macintosh/20090812) MIME-Version: 1.0 To: Harsha References: <4ADAB8E0.3090502@elischer.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-current@freebsd.org, "Robert N. M. Watson" , net@freebsd.org Subject: Re: Page fault in IFNET_WLOCK_ASSERT [if.c and pccbb.c] X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 19 Oct 2009 04:22:37 -0000 Harsha wrote: > On Sat, Oct 17, 2009 at 11:42 PM, Julian Elischer wrote: >> Harsha wrote: >>> wrote: >>>> Looks like a NULL pointer dereference, so perhaps a more traditional bug >>>> -- >>>> could you convert ifindex_alloc_locked+0x71 to a line of code? You can do >>>> this using kgdb on the kernel symbols file, perhaps "l >>>> *ifindex_alloc_locked+0x71". >>> It is the for loop in ifindex_alloc_locked() function- >>> for (idx = 1; idx <= V_if_index; idx++) >>> >>> idx is a local variable, so I figured it is V_if_index is what is >>> causing the page fault. It does look like a NULL pointer reference - I >>> see that V_if_index comes from that vnet instance's value and uses >>> the macro VNET_VNET_PTR() down the chain. Since the call chain is >>> coming from a new thread cbb_event_thread, I believe that this >>> thread's vnet context needs to be set using CURVNET_SET(). >> but only if you have options VIMAGE defined. if not then CURVNET_SET() >> is a NOP > I do have the VIMAGE options turned on. > > Can someone tell me what is the right way to add the vnet context to > cbb_event_thread? have you read the vimage porting document at: http://p4db.freebsd.org/fileLogView.cgi?FSPC=//depot/projects/vimage/porting_to_vimage.txt > > I tried adding context in two locations- > > 1. In cbb_insert() as- > CURVNET_SET(TD_TO_VNET(curthread)); > > 2. In if_alloc() as- > CURVNET_SET(TD_TO_VNET(curthread)); > > or as > > ifp = malloc(sizeof(struct ifnet), M_IFNET, M_WAITOK|M_ZERO); > #ifdef VIMAGE > ifp->if_vnet = curvnet; > if (ifp->if_home_vnet == NULL) > ifp->if_home_vnet = curvnet; > CURVNET_SET(ifp->if_vnet); > #endif CURVNET_SET sets curvnet but you are using it already, 3 lines above. > > But in all the cases I get a warning/error about unused variable > 'saved_vnet' like this- > > cc1: warnings being treated as errors > /usr/src/sys/net/if.c: In function 'if_alloc': > /usr/src/sys/net/if.c:418: warning: unused variable 'saved_vnet' > > The backtrace is in the link I posted earlier. > > Thanks, > Harsha