Subject: Re: [RFC patch 2/5] genirq: add a quick check handler
From: Jon Masters <jonathan@jonmasters.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>, Linus Torvalds <torvalds@osdl.org>,
       Andrew Morton <akpm@linux-foundation.org>, Ingo Molnar <mingo@elte.hu>,
       Arjan van de Veen <arjan@infradead.org>,
       Benjamin Herrenschmidt <benh@kernel.crashing.org>,
       Steven Rostedt <rostedt@goodmis.org>, Sven Dietrich <sdietrich@suse.de>
In-Reply-To: <20081001223301.900862899@linutronix.de>
References: <20081001223213.078984344@linutronix.de>
	 <20081001223301.900862899@linutronix.de>
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Organization: World Organi[sz]ation of Broken Dreams
Date: Wed, 01 Oct 2008 20:47:39 -0400
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On Wed, 2008-10-01 at 23:02 +0000, Thomas Gleixner wrote:

>  struct irqaction {
> +	irq_handler_t quick_check_handler;
>  	irq_handler_t handler;

When we originally discussed this, there was an idea to modify the
request_irq API to take this handler and an IRQF_THREADED type to mark
the interrupt accordingly. I understand why it's a separate function in
this implementation for ease of migration, but what do you think should
happen in the end? Also, I suggest calling this something like
"quiesce_device" because the quickcheck also needs to do that.

We probably need some documentation eventually so people realize what
this "quickcheck" handler is for and what it's not for - under no
circumstances should anything more than the bare minimum be done.
Otherwise it breaks the benefit of deferred threaded handling. It's hard
to enforce that - but this is *not* a return of top/bottom half handling
where you can do whatever crap you like in the quickcheck bit.

Jon.


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