linux-kernel - Re: [PATCH] delaying interrupts in mips [ 2.6.32]

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Date:	Mon, 11 Aug 2014 15:35:03 -0700
From:	David Daney <ddaney@...iumnetworks.com>
To:	Sadasivan Shaiju <sshaiju@...sta.com>
CC:	<linux-kernel@...r.kernel.org>, <ralf@...ux-mips.org>,
	<david.daney@...ium.com>, <shaiju_sada@...oo.com>
Subject: Re: [PATCH] delaying interrupts in mips [ 2.6.32]

On 08/11/2014 03:33 PM, Sadasivan Shaiju wrote:
> Hi David,
>
> Sorry  ,  I  didn't  check  that  .  I  am late  in submitting  it .

OK.  Next time try to apply your patch and test it before submitting.

David Daney

>
> Regards,
> Shaiju.
>
> -----Original Message-----
> From: David Daney [mailto:ddaney@...iumnetworks.com]
> Sent: Monday, August 11, 2014 3:28 PM
> To: Sadasivan Shaiju
> Cc: linux-kernel@...r.kernel.org; ralf@...ux-mips.org;
> david.daney@...ium.com; shaiju_sada@...oo.com
> Subject: Re: [PATCH] delaying interrupts in mips [ 2.6.32]
>
> On 08/11/2014 03:13 PM, Sadasivan Shaiju wrote:
>> Hi ,
>>
>> I  work for Montavista (Cavium Inc) as  a  Technical  Lead .  I want
>> to push some  of the kernel  patches to  rt community (2.6.32 kernel
>> 2.6.33 rt patch)  , so  that  It  will  go  to  the  main line These
>> patches  are reviewed  and approved  by  our system Architect.  I
>> request  you to include  in the main line .
>
> It is already in the "main line":
>
> commit 1bcfecc028686ea32e49b0f4f6e8a665917cb49a
> Author: Yong Zhang <yong.zhang@...driver.com>
> Date:   Thu Jul 19 09:13:53 2012 +0200
>
>       MIPS: Octeon: delay enable irq to ->smp_finish()
>
>       To prepare for smoothing set_cpu_[active|online]() mess up
>
>       Signed-off-by: Yong Zhang <yong.zhang0@...il.com>
>       Cc: Sergei Shtylyov <sshtylyov@...sta.com>
>       Cc: David Daney <david.daney@...ium.com>
>       Acked-by: David Daney <david.daney@...ium.com>
>       Patchwork: https://patchwork.linux-mips.org/patch/3845/
>       Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
>
> Why are you sending it again?
>
> David Daney
>
>
>
>     These  issues  were  reported  by our
>> customer CISCO .
>>
>> Problem Description:
>> When CONFIG_DEBUG_PREEMPT is enabled the following stack trace occurs.
>>
>> [ 170.814470] BUG: using smp_processor_id() in preemptible [00000000]
>> code: sirq-timer/4/62
>> [ 170.814482] caller is hrtimer_run_pending+0x10/0x20 [ 170.814488]
>> Call Trace:
>> [ 170.814496] [<ffffffff8010d844>] dump_stack+0x8/0x34 [ 170.814507]
>> [<ffffffff803c2598>] debug_smp_processor_id+0xe0/0xf0 [ 170.814517]
>> [<ffffffff80254158>] hrtimer_run_pending+0x10/0x20 [ 170.814528]
>> [<ffffffff80242400>] run_timer_softirq+0x60/0x348 [ 170.814539]
>> [<ffffffff8023ae80>] run_ksoftirqd+0x1c8/0x348 [ 170.814550]
>> [<ffffffff802503f8>] kthread+0x88/0x90 [ 170.814561]
>> [<ffffffff80206c80>] kernel_thread_helper+0x10/0x18
>>
>> Root Cause:
>> Interrupt was occurring before the processor was completely up, and
>> the softirq threads were unable to schedule on the processor and then
>> ran on the wrong CPU.
>>
>> How Solved:
>> Enabling of interrupt has been delayed till smp_finish so that
>> kthread_bind can safely bind threads to any possible CPU.
>>
>> I request you  to merge  the above patch  to the  main line .  If  any
>> questions please contact me atsshaiju@...sta.com
>> (shaiju_sada@...oo.com)
>>
>> Regards,
>> Shaiju.
>>
>>
>> 0001-Interrupt-delaying-enabling-of-interrupt.patch
>>
>>
>>   From 58512475cba93003c23f2b380b573e64eebcabd5 Mon Sep 17 00:00:00
>> 2001
>> From: Sadasivan Shaiju<sshaiju@...sta.com>
>> Date: Mon, 20 Feb 2012 13:25:50 -0800
>> Subject: [PATCH] Interrupt : delaying enabling of interrupt
>>
>> Source: MontaVista Software, LLC
>> MR: 47157
>> Type: Defect Fix
>> Disposition: Local
>> ChangeID: 48c837329556b161f3111e6fded1c9857fa3a149
>> Description:
>>
>> This patch is to delay the enabling of interrupt till smp_finish . So
>> that kthread_bind can safely bind threads to any possible cpu. Without
>> this change interrupt should occur beofre  the  processor was
>> completely up, and  the softirq threads were unable to schedule on the
>> processor and  then  ran on the wrong CPU.
>>
>> Signed-off-by: Sadasivan Shaiju<sshaiju@...sta.com>
>> ---
>>    arch/mips/cavium-octeon/smp.c |    3 ++-
>>    1 files changed, 2 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/mips/cavium-octeon/smp.c
>> b/arch/mips/cavium-octeon/smp.c index ff21542..c7de7ac 100644
>> --- a/arch/mips/cavium-octeon/smp.c
>> +++ b/arch/mips/cavium-octeon/smp.c
>> @@ -308,7 +308,6 @@ static void octeon_init_secondary(void)
>>    	octeon_init_cvmcount();
>>
>>    	octeon_irq_setup_secondary();
>> -	raw_local_irq_enable();
>>    }
>>
>>    /**
>> @@ -365,6 +364,8 @@ static void octeon_smp_finish(void)
>>
>>    	/* to generate the first CPU timer interrupt */
>>    	write_c0_compare(read_c0_count() + mips_hpt_frequency / HZ);
>> +	/* enable local interrupts */
>> +	raw_local_irq_enable();
>>    }
>>
>>    /**
>> -- 1.7.0.1

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