From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756742Ab0JDSTn (ORCPT ); Mon, 4 Oct 2010 14:19:43 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:53924 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755022Ab0JDSTm (ORCPT ); Mon, 4 Oct 2010 14:19:42 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: "Hans J. Koch" Cc: Greg KH , Greg KH , linux-kernel@vger.kernel.org, Thomas Gleixner References: <20100917205946.GF2522@local> <20100924104555.GC1819@silverbox.local> <20100924173106.GA4966@silverbox.local> <20100925003308.GA29910@suse.de> <20100926192142.GA7252@kroah.com> <20101004123447.GB9961@silverbox.local> Date: Mon, 04 Oct 2010 11:19:34 -0700 In-Reply-To: <20101004123447.GB9961@silverbox.local> (Hans J. Koch's message of "Mon, 4 Oct 2010 14:34:47 +0200") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-XM-SPF: eid=;;;mid=;;;hst=in01.mta.xmission.com;;;ip=98.207.157.188;;;frm=ebiederm@xmission.com;;;spf=neutral X-SA-Exim-Connect-IP: 98.207.157.188 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 1.5 XMNoVowels Alpha-numberic number with no vowels * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -3.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa03 1397; Body=1 Fuz1=1 Fuz2=1] * 0.5 XM_Body_Dirty_Words Contains a dirty word * 0.0 T_TooManySym_01 4+ unique symbols in subject * 0.4 UNTRUSTED_Relay Comes from a non-trusted relay X-Spam-DCC: XMission; sa03 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;"Hans J. Koch" X-Spam-Relay-Country: Subject: Re: [PATCH 5/5] uio: Implement hotunplug support, using libunload X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Fri, 06 Aug 2010 16:31:04 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org "Hans J. Koch" writes: > On Sun, Sep 26, 2010 at 03:49:03PM -0700, Eric W. Biederman wrote: >> >> With this change it is possible to remove a module that implements >> a uio device, or to remove the underlying hardware device of a uio >> device withot crashing the kernel, or causing user space more problems >> than just an I/O error. > > Well, that I/O error can also be a segfault if userspace accesses > memory previously mmap'ed. So a userspace program needs to properly > handle -EIO from read(), and has to handle SIG_SEGV. It is SIG_BUS (just like truncate), but yes. If userspace doesn't handle there error it can go down. All of which is a better state then the current version where the kernel crash if you hotunplug a uio device. > This should also > be mentioned in Documentation/DocBook/uio-howto.tmpl. > Or do you have a better solution? A better solution for? Eric