linux-kernel - Re: [RFC][PATCH] irq: remove IRQF

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Message-Id: <1236009588.5330.729.camel@laptop>
Date:	Mon, 02 Mar 2009 16:59:48 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Matthew Wilcox <matthew@....cx>
Cc:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	lkml <linux-kernel@...r.kernel.org>,
	linux-arch <linux-arch@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [RFC][PATCH] irq: remove IRQF_DISABLED

On Mon, 2009-03-02 at 08:47 -0700, Matthew Wilcox wrote:
> On Mon, Mar 02, 2009 at 03:43:03PM +0100, Ingo Molnar wrote:
> > * Peter Zijlstra <peterz@...radead.org> wrote:
> > > Hi Linus,
> > > 
> > > Would you be willing to take such a patch?
> > > 
> > > Its a rather big one, but if you think its a good idea, I can 
> > > generate one against whatever tree is needed.
> > > 
> > > Provided I didn't break any !genirq stuff.. then again, that 
> > > might be a nice incentive to fix up those last few archs.
> > 
> > look good IMO. If there are no objections, and given that it 
> 
> Perhaps someone could explain why we want to remove it?  I just added
> it to AHCI for good reason, so I'd like to know why we think it should
> be taken away.
> 
> I added it because I was adding support for per-port interrupts.
> In the interrupt handler, we take the *host* lock (not the port lock).
> With multiple interrupt handlers per host, we would have to disable
> interrupts in the interrupt handler before taking the lock.  Which is
> foolish because we've just re-enabled interrupts in the genirq code.
> Specifying IRQF_DISABLED means we just run with interrupts disabled.
> 
> You can argue that libata/ahci should be using a per-port lock, and
> I wouldn't disagree.  But I'd still like to know why IRQF_DISABLED is
> being removed.

The idea is to mandate IRQF_DISABLED for everybody, and since it doesn't
do any good to have it a flag if you have it always enabled, remove
it ;-)



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