linux-kernel - How to chip->startup() with IRQs disabled

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Message-ID: <74B0AE1BA53C37449DE49BB274F9A2DBC4D07C@orion8.netlogicmicro.com>
Date:	Thu, 8 Sep 2011 16:13:54 -0700
From:	"Om Narasimhan" <onarasimhan@...logicmicro.com>
To:	<linux-kernel@...r.kernel.org>
Subject: How to chip->startup() with IRQs disabled

Hi,
I am working on a MIPS chip with multiple cores. I have defined 
static struct irq_chip new_plat_chip = {
...
	.startup = n_irq_startup,
	.mask = n_irq_shutdown,
...
};

In n_irq_startup(), I have to make sure that all cores have set RVEC bit and corresponding EIMR bit. So, I try using on_each_cpu() (because EIMR can be set only by running code on that particular cpu) to run a function to set EIMR.

n_irq_startup() is called as chip->startup() from __setup_irq() (from request_threaded_irq, in turn from request_irq() ) with a spin lock held (desc->lock, in kernel/irq/manage.c).  This causes a stack dump from on_each_cpu(). Since it is wrong to call on_each_cpu with interrupts disabled, I want to change this piece of code.

I am wondering how other SMP mips system implement this. Any comments or pointers will be helpful.

I am not in the mailing list, please CC me in replies.

I tried sent this to linux-mips, but no replies. So, trying with a larger audience. (http://www.spinics.net/lists/mips/msg41902.html)
Om.
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