linux-kernel - Re: [patch 03/26] powerpc: eeh: Kill another abuse of irq

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Message-ID: <alpine.DEB.2.02.1402241232030.21251@ionos.tec.linutronix.de>
Date:	Mon, 24 Feb 2014 12:32:46 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Gavin Shan <shangw@...ux.vnet.ibm.com>
cc:	LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	ppc <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [patch 03/26] powerpc: eeh: Kill another abuse of irq_desc

On Mon, 24 Feb 2014, Gavin Shan wrote:
> On Sun, Feb 23, 2014 at 09:40:09PM -0000, Thomas Gleixner wrote:
> >commit 91150af3a (powerpc/eeh: Fix unbalanced enable for IRQ) is
> >another brilliant example of trainwreck engineering.
> >
> >The patch "fixes" the issue of an unbalanced call to irq_enable()
> >which causes a prominent warning by checking the disabled state of the
> >interrupt line and call conditionally into the core code.
> >
> >This is wrong in two aspects:
> >
> >1) The warning is there to tell users, that they need to fix their
> >   asymetric enable/disable patterns by finding the root cause and
> >   solving it there.
> >
> >   It's definitely not meant to work around it by conditionally
> >   calling into the core code depending on the random state of the irq
> >   line.
> >
> >   Asymetric irq_disable/enable calls are a clear sign of wrong usage
> >   of the interfaces which have to be cured at the root and not by
> >   somehow hacking around it.
> >
> >2) The abuse of core internal data structure instead of using the
> >   proper interfaces for retrieving the information for the 'hack
> >   around'
> >
> >   irq_desc is core internal and it's clear enough stated.
> >
> >Replace at least the irq_desc abuse with the proper functions and add
> >a big fat comment why this is absurd and completely wrong.
> >
> 
> Thanks for pointing it out. I think we might have this patch for now
> and I'll look into individual drivers to fix the unbalanced function
> calls later one by one.

Fine with me. You wont escape my scan scripts :)

Thanks,

	tglx
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