From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751447AbcEIOhK (ORCPT ); Mon, 9 May 2016 10:37:10 -0400 Received: from mx2.suse.de ([195.135.220.15]:43871 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751213AbcEIOhI (ORCPT ); Mon, 9 May 2016 10:37:08 -0400 Subject: Re: [PATCH v4 6/6] hwmon: use smp_call_on_cpu() for dell-smm i8k To: =?UTF-8?Q?Pali_Roh=c3=a1r?= References: <1459833007-11618-1-git-send-email-jgross@suse.com> <1459833007-11618-7-git-send-email-jgross@suse.com> <20160405145414.GB27359@roeck-us.net> <201604052131.52765@pali> <20160421105724.GK29406@pali> <5718D1D4.3040309@suse.com> <20160421132735.GR29406@pali> Cc: Guenter Roeck , linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, boris.ostrovsky@oracle.com, david.vrabel@citrix.com, mingo@redhat.com, peterz@infradead.org, Douglas_Warzecha@dell.com, jdelvare@suse.com, tglx@linutronix.de, hpa@zytor.com, jeremy@goop.org, chrisw@sous-sol.org, akataria@vmware.com, rusty@rustcorp.com.au, virtualization@lists.linux-foundation.org, x86@kernel.org From: Juergen Gross Message-ID: <5730A08D.60100@suse.com> Date: Mon, 9 May 2016 16:37:01 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.0 MIME-Version: 1.0 In-Reply-To: <20160421132735.GR29406@pali> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 21/04/16 15:27, Pali Rohár wrote: > On Thursday 21 April 2016 15:12:52 Juergen Gross wrote: >> On 21/04/16 12:57, Pali Rohár wrote: >>> On Tuesday 05 April 2016 21:31:52 Pali Rohár wrote: >>>> On Tuesday 05 April 2016 16:54:14 Guenter Roeck wrote: >>>>> On Tue, Apr 05, 2016 at 07:10:07AM +0200, Juergen Gross wrote: >>>>>> Use the smp_call_on_cpu() function to call system management >>>>>> mode on cpu 0. >>>>>> Make call secure by adding get_online_cpus() to avoid e.g. suspend >>>>>> resume cycles in between. >>>>>> >>>>>> Signed-off-by: Juergen Gross >>>>>> --- >>>>>> V4: add call to get_online_cpus() >>>>> >>>>> Pali, any chance to test this ? >>>> >>>> I can test it, but just on machine where (probably) smm calls can be >>>> send from any cpu... Need some time for testing and I believe I can do >>>> that at the end of the week. >>> >>> Sorry I had absolutely no more free time last weekend :-( And same >>> prediction is for this weekend and also next one... >> >> Pali, I've got a Dell laptop (Latitude E6440) here. Would this device be >> okay for a test? > > Hi! > > Proper regression test should check if this patch does not break any > function or drivers dependent on dcdbas.ko. And should be done on both > notebook devices: which needs to issue that smm call on cpu 0 and also > on which it is not needed. Hmm, couldn't get one which needs smm to be called on cpu 0. OTOH I've done various tests and added a printk() in raise_smm() and i8k_smm_func() issuing the cpu number it was called on. > Some notebooks which needs smm call to issued from cpu 0 can be found in > git commit messages of i8k, dell-laptop or dcdbas kernel drivers. > >> What would you do for testing? In case you can give me >> some hints how to do a sensible test I'd do it. > > Test e.g. dell-laptop.ko driver. It provides /sys interface for changing > keyboard backlight or changing rfkill switches (bluetooth wifi). Done. > Also test tools from libsmbios (userspace) package. Done. > There must be no difference in output/functionality with or without your > patches. Verified. >> I've verified by adding a printk() to smp_call_on_cpu() that at least >> one of the modified drivers has been used during system boot. > > Also you can patch i8k/dcdbas smm function to print cpu number on which > is code running (to verify that it was really called on cpu 0 as > needed). Done. I tested suspend/resume, too, as adding get_online_cpus() might have changed behavior. Worked like a charm. :-) Juergen