Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758247AbZDKTck (ORCPT ); Sat, 11 Apr 2009 15:32:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755098AbZDKTcc (ORCPT ); Sat, 11 Apr 2009 15:32:32 -0400 Received: from mail-bw0-f169.google.com ([209.85.218.169]:34979 "EHLO mail-bw0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753480AbZDKTcb (ORCPT ); Sat, 11 Apr 2009 15:32:31 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:mail-followup-to:references :mime-version:content-type:content-disposition:in-reply-to :user-agent; b=A7KrkEPxnvTQRbODcFA+ih7LMH6ppi4gQ9psP9rgdU7RPJqtML/iJO/I1UIVPArz0t pR8EWKefxdmWKSmIM81Vmc0J6r7p91NqxdLwEtu9wDzvxTMgpjL7ZHN/8iuufl7aOm1E L77hUBCu6ItQosEdVZ1vQTLMJcT2bpi0gr2PM= Date: Sat, 11 Apr 2009 21:32:26 +0200 From: Andrea Righi To: Andrew Morton Cc: Stefan Richter , Krzysztof Helt , Eric Miao , LKML , Geert Uytterhoeven , "Rafael J. Wysocki" , Andrey Borzenkov , "Antonino A. Daplas" , linux-fbdev-devel@lists.sourceforge.net, linux-pm@lists.linux-foundation.org, Dave Jones , Harvey Harrison , Johannes Weiner , Pavel Roskin Subject: Re: [REGRESSION] commit 66c1ca0: {fbmem: fix fb_info->lock and mm->mmap_sem ...} causes Xfbdev not working Message-ID: <20090411193226.GA5440@linux> Mail-Followup-To: Andrew Morton , Stefan Richter , Krzysztof Helt , Eric Miao , LKML , Geert Uytterhoeven , "Rafael J. Wysocki" , Andrey Borzenkov , "Antonino A. Daplas" , linux-fbdev-devel@lists.sourceforge.net, linux-pm@lists.linux-foundation.org, Dave Jones , Harvey Harrison , Johannes Weiner , Pavel Roskin References: <20090409125850.GA2727@linux> <20090410222122.87be60f6.krzysztof.h1@poczta.fm> <20090410220521.GB21294@linux> <20090411080415.7fe924a2.krzysztof.h1@poczta.fm> <49E05C36.9040204@s5r6.in-berlin.de> <20090411110840.GA7108@linux> <20090411150359.GA8265@linux> <20090411112131.cc38dcf0.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090411112131.cc38dcf0.akpm@linux-foundation.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1352 Lines: 32 On Sat, Apr 11, 2009 at 11:21:31AM -0700, Andrew Morton wrote: > On Sat, 11 Apr 2009 17:04:00 +0200 Andrea Righi wrote: > > > fbdev: fix info->lock deadlock in fbcon_event_notify() > > > > fb_notifier_call_chain() is called with info->lock held, i.e. in > > do_fb_ioctl() => FBIOPUT_VSCREENINFO => fb_set_var() and the some > > notifier callbacks, like fbcon_event_notify(), try to re-acquire > > info->lock again. > > > > Remove the lock/unlock_fb_info() in all the framebuffer notifier > > callbacks' and be sure to always call fb_notifier_call_chain() with > > info->lock held. > > Thanks. So do you think we should proceed with this patch instead of > reverting 66c1ca0? Yes, there's no need to revert 66c1ca0 now, otherwise we'll simply reintroduce the info->lock / mm->mmap_sem circular locking dependency. I'd like to test the fbdev mode switching, but it seems intelfb doesn't support it with LVDS ports (and at the moment I've not a CRT here...). Anyway, if someone will have troubles with mode switching I'm quite sure we can fix it on top of this patch. -Andrea -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/