From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH 1/11] Add generic helpers for arch IPI function calls Date: Tue, 22 Apr 2008 16:43:57 +0200 Message-ID: <1208875437.7115.271.camel@twins> References: <1208851058-8500-1-git-send-email-jens.axboe@oracle.com> <1208851058-8500-2-git-send-email-jens.axboe@oracle.com> <480DACDD.7040108@qumranet.com> <20080422092230.GW12774@kernel.dk> <20080422111403.GX12774@kernel.dk> <1208869254.7115.258.camel@twins> <20080422142543.GG12774@kernel.dk> <480DF861.6000705@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <480DF861.6000705-atKUWr5tajBWk0Htik3J/w@public.gmane.org> Sender: linux-arch-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: To: Avi Kivity Cc: Jens Axboe , linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, npiggin-l3A5Bk7waGM@public.gmane.org, torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org On Tue, 2008-04-22 at 17:38 +0300, Avi Kivity wrote: > Jens Axboe wrote: > >> Introducing this fallback will make any usage from irq disabled context > >> deadlock prone. > >> > >> I rather like the current interface. > >> > > > > Hmm good point, I'll back that bit out again. > > > > But then you need to fix all callers to handle errors. Sure. > Perhaps we need a new flag for failable async IPIs (or better, API). > I'm pretty sure no one uses s_c_f_s() from irq disabled context on x86, > since it will WARN_ON(irqs_disabled()). Yeah, no current users, but that doesn't say I don't want to add new ones ;-) From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from pentafluge.infradead.org ([213.146.154.40]:34248 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1764130AbYDVOo1 (ORCPT ); Tue, 22 Apr 2008 10:44:27 -0400 Subject: Re: [PATCH 1/11] Add generic helpers for arch IPI function calls From: Peter Zijlstra In-Reply-To: <480DF861.6000705@qumranet.com> References: <1208851058-8500-1-git-send-email-jens.axboe@oracle.com> <1208851058-8500-2-git-send-email-jens.axboe@oracle.com> <480DACDD.7040108@qumranet.com> <20080422092230.GW12774@kernel.dk> <20080422111403.GX12774@kernel.dk> <1208869254.7115.258.camel@twins> <20080422142543.GG12774@kernel.dk> <480DF861.6000705@qumranet.com> Content-Type: text/plain Date: Tue, 22 Apr 2008 16:43:57 +0200 Message-ID: <1208875437.7115.271.camel@twins> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Avi Kivity Cc: Jens Axboe , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, npiggin@suse.de, torvalds@linux-foundation.org Message-ID: <20080422144357.NE27ZDOpTB316mDa854Als6fwLHQYC9gBOiu0XN5r2E@z> On Tue, 2008-04-22 at 17:38 +0300, Avi Kivity wrote: > Jens Axboe wrote: > >> Introducing this fallback will make any usage from irq disabled context > >> deadlock prone. > >> > >> I rather like the current interface. > >> > > > > Hmm good point, I'll back that bit out again. > > > > But then you need to fix all callers to handle errors. Sure. > Perhaps we need a new flag for failable async IPIs (or better, API). > I'm pretty sure no one uses s_c_f_s() from irq disabled context on x86, > since it will WARN_ON(irqs_disabled()). Yeah, no current users, but that doesn't say I don't want to add new ones ;-)