linux-kernel - Re: Can we conditionally force threading irq with primary and thread handler?

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Message-ID: <alpine.DEB.2.11.1512032324410.4201@nanos>
Date:	Thu, 3 Dec 2015 23:33:14 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Yunhong Jiang <yunhong.jiang@...ux.intel.com>
cc:	okuno.kohji@...panasonic.com, linux-kernel@...r.kernel.org
Subject: Re: Can we conditionally force threading irq with primary and thread
 handler?

Yunhong,

On Thu, 3 Dec 2015, Yunhong Jiang wrote:

> Hi, Thomas
> 	On Commit 2a1d3ab8986d1b2 ("genirq: Handle force threading of irqs 
> with primary and thread handler"), even if the caller of 
> request_threaded_irq() provides a primary handler, that primary handler will 
> be invoked in thread context. This may cause some latency issue for high 
> real time requirement.
> 
> 	I checked the discussion on https://lkml.org/lkml/2015/9/19/372 with 
> Okuno and seems we need this change only if the irq is shared, otherwise, we 
> can still use Okuno's mechanism, am I right? Do you think it's ok to force 
> the primary handler for shared IRQ, otherwise, clear the IRQF_ONESHOT?

If you want to avoid that the primary handler is force threaded, then
you can indicate that with IRQF_NO_THREAD.

Thanks,

	tglx

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