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

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Message-ID: <5bf77c903d6df6cfe656a3585c314df1@mail.gmail.com>
Date:	Mon, 11 Aug 2014 15:13:19 -0700
From:	Sadasivan Shaiju <sshaiju@...sta.com>
To:	linux-kernel@...r.kernel.org, ralf@...ux-mips.org,
	david.daney@...ium.com
Cc:	shaiju_sada@...oo.com
Subject: [PATCH] delaying interrupts in mips [ 2.6.32]

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 .  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 at sshaiju@...sta.com (shaiju_sada@...oo.com)

Regards,
Shaiju.

Download attachment "0001-Interrupt-delaying-enabling-of-interrupt.patch" of type "application/octet-stream" (1411 bytes)