From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Srivatsa S. Bhat" Subject: Re: [PATCH 2/6] irq_work: Implement remote queueing Date: Wed, 25 Jun 2014 22:27:24 +0530 Message-ID: <53AAFF74.8090308@linux.vnet.ibm.com> References: <53A9E0A5.5040402@wwwdotorg.org> <20140625051234.GD6758@twins.programming.kicks-ass.net> <20140625051721.GG3588@twins.programming.kicks-ass.net> <53AA6E11.1000404@linux.vnet.ibm.com> <20140625093657.GN19860@laptop.programming.kicks-ass.net> <20140625093944.GV16155@laptop.programming.kicks-ass.net> <53AA9B68.4050104@linux.vnet.ibm.com> <53AA9C43.3020903@linux.vnet.ibm.com> <20140625101915.GO19860@laptop.programming.kicks-ass.net> <53AAF779.8060006@wwwdotorg.org> <20140625163820.GC3935@laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from e23smtp01.au.ibm.com ([202.81.31.143]:51627 "EHLO e23smtp01.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757815AbaFYQ7J (ORCPT ); Wed, 25 Jun 2014 12:59:09 -0400 Received: from /spool/local by e23smtp01.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 26 Jun 2014 02:59:07 +1000 In-Reply-To: <20140625163820.GC3935@laptop> Sender: linux-next-owner@vger.kernel.org List-ID: To: Peter Zijlstra , Stephen Warren Cc: Frederic Weisbecker , LKML , Andrew Morton , Eric Dumazet , Ingo Molnar , Kevin Hilman , "Paul E. McKenney" , Thomas Gleixner , Viresh Kumar , "linux-next@vger.kernel.org" On 06/25/2014 10:08 PM, Peter Zijlstra wrote: > On Wed, Jun 25, 2014 at 10:23:21AM -0600, Stephen Warren wrote: >> On 06/25/2014 04:19 AM, Peter Zijlstra wrote: >>> On Wed, Jun 25, 2014 at 03:24:11PM +0530, Srivatsa S. Bhat wrote: >>>> Wait, that was a stupid idea. hotplug_cfd() already invokes irq_work_run >>>> indirectly via flush_smp_call_function_queue(). So irq_work_cpu_notify() >>>> doesn't need to invoke it again, AFAIU. So perhaps we can get rid of >>>> irq_work_cpu_notify() altogether? >>> >>> Just so... >>> >>> getting up at 6am and sitting in an airport terminal doesn't seem to >>> agree with me; any more silly fail here? >>> >>> --- >>> Subject: irq_work: Remove BUG_ON in irq_work_run() >>> From: Peter Zijlstra >>> Date: Wed Jun 25 07:13:07 CEST 2014 >>> >>> Because of a collision with 8d056c48e486 ("CPU hotplug, smp: flush any >>> pending IPI callbacks before CPU offline"), which ends up calling >>> hotplug_cfd()->flush_smp_call_function_queue()->irq_work_run(), which >>> is not from IRQ context. >>> >>> And since that already calls irq_work_run() from the hotplug path, >>> remove our entire hotplug handling. >> >> Tested-by: Stephen Warren >> >> [with the s/static// already mentioned in this thread, obviously:-)] > > Right; I pushed out a fixed version right before loosing my tubes at the > airport :-) > > https://git.kernel.org/cgit/linux/kernel/git/peterz/queue.git/commit/?h=timers/nohz&id=921d8b81281ecdca686369f52165d04fa3505bd7 > This version looks good. Reviewed-by: Srivatsa S. Bhat Regards, Srivatsa S. Bhat > I've not gotten wu build bot spam on it so it must be good ;-) > > In any case, I'll add your tested-by and update later this evening. >