linux-kernel - Re: [patch 062/104] ACPI: EC: count interrupts only if called from interrupt handler.

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Message-ID: <20081205130649.GB1750@ucw.cz>
Date:	Fri, 5 Dec 2008 14:06:49 +0100
From:	Pavel Machek <pavel@...e.cz>
To:	Greg KH <gregkh@...e.de>
Cc:	linux-kernel@...r.kernel.org, stable@...nel.org,
	Justin Forbes <jmforbes@...uxtx.org>,
	Zwane Mwaikambo <zwane@....linux.org.uk>,
	Theodore Ts'o <tytso@....edu>,
	Randy Dunlap <rdunlap@...otime.net>,
	Dave Jones <davej@...hat.com>,
	Chuck Wolber <chuckw@...ntumlinux.com>,
	Chris Wedgwood <reviews@...cw.f00f.org>,
	Michael Krufky <mkrufky@...uxtv.org>,
	Chuck Ebbert <cebbert@...hat.com>,
	Domenico Andreoli <cavokz@...il.com>, Willy Tarreau <w@....eu>,
	Rodrigo Rubira Branco <rbranco@...checkpoint.com>,
	Jake Edge <jake@....net>, Eugene Teo <eteo@...hat.com>,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk,
	Alexey Starikovskiy <astarikovskiy@...e.de>,
	Len Brown <len.brown@...el.com>,
	Alan Jenkins <alan-jenkins@...fmail.co.uk>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [patch 062/104] ACPI: EC: count interrupts only if called from
	interrupt handler.

On Wed 2008-12-03 11:53:00, Greg KH wrote:
> 2.6.27-stable review patch.  If anyone has any objections, please let us know.
> 
> ------------------
> From: Alexey Starikovskiy <astarikovskiy@...e.de>
> 
> commit 7b4d469228a92a00e412675817cedd60133de38a upstream.
> 
> fix 2.6.28 EC interrupt storm regression
> 

That changelog is pretty useless :-(.

> @@ -219,7 +219,8 @@ static void gpe_transaction(struct acpi_
>  	goto unlock;
>  err:
>  	/* false interrupt, state didn't change */
> -	++ec->curr->irq_count;
> +	if (in_interrupt())
> +		++ec->curr->irq_count;
>  unlock:
>  	spin_unlock_irqrestore(&ec->curr_lock, flags);
>  }

Is preempt_count() reliable with !config_preempt, too?

Using in_interrupt here is quite ugly... definitely worth a comment
and perhaps gpe_transaction should get explicit 'am I in interrupt'
parameter.

At least RT kernels plan on moving interrupt handlers to threads...

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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