From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755384AbaJXTxd (ORCPT ); Fri, 24 Oct 2014 15:53:33 -0400 Received: from mail-la0-f51.google.com ([209.85.215.51]:42277 "EHLO mail-la0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752160AbaJXTxc (ORCPT ); Fri, 24 Oct 2014 15:53:32 -0400 Date: Fri, 24 Oct 2014 21:50:29 +0200 From: Johan Hovold To: Felipe Balbi Cc: Johan Hovold , Russell King , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ARM: remove redundant irq disable at halt and restart Message-ID: <20141024195029.GE19377@localhost> References: <1414177592-14547-1-git-send-email-johan@kernel.org> <20141024191627.GA11455@saruman> <20141024192111.GC11455@saruman> <20141024192845.GC19377@localhost> <20141024194250.GF11455@saruman> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141024194250.GF11455@saruman> User-Agent: Mutt/1.5.22 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 24, 2014 at 02:42:50PM -0500, Felipe Balbi wrote: > On Fri, Oct 24, 2014 at 09:28:45PM +0200, Johan Hovold wrote: > > On Fri, Oct 24, 2014 at 02:21:11PM -0500, Felipe Balbi wrote: > > > On Fri, Oct 24, 2014 at 02:16:27PM -0500, Felipe Balbi wrote: > > > > On Fri, Oct 24, 2014 at 09:06:32PM +0200, Johan Hovold wrote: > > > > > Remove redundant local_irq_disable() at machine halt and restart. > > > > > > > > > > Since commit 44424c34049f ("ARM: 7803/1: Fix deadlock scenario with > > > > > smp_send_stop()") interrupts are disabled before stopping secondary > > > > > CPUs. > > > > > > > > Assuming this is correct, you should have: > > > > > > > > Fixes: 44424c3 (ARM: 7803/1: Fix deadlock scenario with smp_send_stop()) > > > > Cc: # v3.12+ > > > > It's not a bug. Just a redundant disabling of already disabled > > interrupts, something which could possibly lead someone to believe that > > interrupts could be re-enabled by the power-off handler. I meant re-enabled by arm_pm_restart(). > I didn't dig any of this out but I'll assume you did :-) So I withdraw > my comment ;-) > > > > > > diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c > > > > > index a35f6ebbd2c2..5663ab57cf07 100644 > > > > > --- a/arch/arm/kernel/process.c > > > > > +++ b/arch/arm/kernel/process.c > > > > > @@ -195,7 +195,6 @@ void machine_halt(void) > > > > > local_irq_disable(); > > > > > smp_send_stop(); > > > > > > > > > > - local_irq_disable(); > > > > > while (1); > > > > > } > > > > > > > > > > @@ -237,7 +236,6 @@ void machine_restart(char *cmd) > > > > > > > > > > /* Whoops - the platform was unable to reboot. Tell the user! */ > > > > > printk("Reboot failed -- System halted\n"); > > > > > - local_irq_disable(); > > > > > > > > ... but wouldn't this reintroduce the the buck which that commit fixed ? > > > > > > s/buck/bug :-) my fingers have a mind of their own, aparently. > > > > :) > > > > No, the interrupts would still be disabled. > > alright... so far I couldn't find where IRQs are disable before > machine_power_off() is called. Starting a do_poweroff(), couldn't find > it... Oh well, I'll keep digging. It's done a few lines above in the same function. ;) void machine_restart(char *cmd) { local_irq_disable(); ^^^ smp_send_stop(); arm_pm_restart(reboot_mode, cmd); /* Give a grace period for failure to restart of 1s */ mdelay(1000); /* Whoops - the platform was unable to reboot. Tell the user! */ printk("Reboot failed -- System halted\n"); local_irq_disable(); while (1); } [ and similarly in machine_power_off(). ] Johan