Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752063AbbG2NRi (ORCPT ); Wed, 29 Jul 2015 09:17:38 -0400 Received: from mail-qk0-f179.google.com ([209.85.220.179]:36576 "EHLO mail-qk0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750898AbbG2NRe (ORCPT ); Wed, 29 Jul 2015 09:17:34 -0400 Message-ID: <55B8D26A.7000402@hurleysoftware.com> Date: Wed, 29 Jul 2015 09:17:30 -0400 From: Peter Hurley User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.8.0 MIME-Version: 1.0 To: Thomas Gleixner CC: Taichi Kageyama , "gregkh@linuxfoundation.org" , "jiang.liu@linux.intel.com" , "linux-serial@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "jslaby@suse.cz" , "prarit@redhat.com" , Naoya Horiguchi Subject: Re: [RFC PATCH v2 0/3] genirq, serial: 8250: Workaround to avoid irq=0 for console References: <1438157443-19447-1-git-send-email-t-kageyama@cp.jp.nec.com> <55B8BE39.6080500@hurleysoftware.com> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2515 Lines: 80 On 07/29/2015 07:53 AM, Thomas Gleixner wrote: > On Wed, 29 Jul 2015, Peter Hurley wrote: >> On 07/29/2015 06:32 AM, Thomas Gleixner wrote: >>> On Wed, 29 Jul 2015, Taichi Kageyama wrote: >>>> - Keep interrupt disabled on the CPU which is used to detect >>>> an interrupt during the timeout of autoconfig_irq(). >>>> + Kick printk() on the CPU which detects interrupt >>>> from a console serial port. >>> >>> This is wrong to begin with. How is that supposed to work on an UP >>> machine? Not at all. >>> >>> So no, fix the code which has interrupts disabled accross autoprobing >>> and do not try to apply bandaids somewhere else. >> >> Like printk() from some unrelated driver? > > If that's the cause for the wreckage then yes, we need a way to tell > the printk code not to call into the driver until that initialization > step is done. It's that simple. Like this? --- >% -- Subject: [PATCH] genirq: Disable printk() during irq probe printk() disables interrupts for extended periods of time while outputting to console drivers. This breaks irq probing since the triggered irq may not be serviced (in time) if scheduled on the printk() cpu. Claim the console_lock() which effectively disables console output. Signed-off-by: Peter Hurley --- kernel/irq/autoprobe.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/kernel/irq/autoprobe.c b/kernel/irq/autoprobe.c index 0119b9d..47535d2 100644 --- a/kernel/irq/autoprobe.c +++ b/kernel/irq/autoprobe.c @@ -39,6 +39,13 @@ unsigned long probe_irq_on(void) */ async_synchronize_full(); mutex_lock(&probing_active); + + /* + * printk() breaks irq probing - disable printk output until probe + * completes + */ + console_lock(); + /* * something may have generated an irq long ago and we want to * flush such a longstanding irq before considering it as spurious. @@ -132,6 +139,7 @@ unsigned int probe_irq_mask(unsigned long val) } raw_spin_unlock_irq(&desc->lock); } + console_unlock(); mutex_unlock(&probing_active); return mask & val; @@ -174,6 +182,7 @@ int probe_irq_off(unsigned long val) } raw_spin_unlock_irq(&desc->lock); } + console_unlock(); mutex_unlock(&probing_active); if (nr_of_irqs > 1) -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/