Date: Mon, 30 Jun 2008 10:37:27 -0400 (EDT)
From: Alan Stern <stern@rowland.harvard.edu>
To: David Brownell <david-b@pacbell.net>
cc: Stefan Becker <Stefan.Becker@nokia.com>, <linux-kernel@vger.kernel.org>,
       <linux-usb@vger.kernel.org>,
       ext Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: PATCH: 2.6.26-rc8: Fix IRQF_DISABLED for shared interrupts
In-Reply-To: <200806300415.15796.david-b@pacbell.net>
Message-ID: <Pine.LNX.4.44L0.0806301035510.2708-100000@iolanthe.rowland.org>
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On Mon, 30 Jun 2008, David Brownell wrote:

> On Monday 30 June 2008, Stefan Becker wrote:
> > It seems IRQF_SHARED | IRQF_DISABLED has already been discussed several 
> > times on LKML:
> 
> Given that, I'm surprised that nobody has added a warning that
> prints when those two flags are both passed to request_irq().
> 
> The problems have been around for a long time, "tested" and known
> to be broken.  They'll never go away without nag messages nudging
> developers to fix the problems.
> 
> 
> > Alan: should I try to implement his choice (f) insteadn, i.e. drop 
> > IRQF_DISABLED from USB HCD interrupts and disable interrupts in 
> > usb_hcd_irq() instead?
> 
> That's the best solution for USB, given that IRQF_DISABLED isn't
> going to do what it claims to do.

I agree.  Note that IRQF_DISABLED is used in hcd_pci.c as well as in
quite a few files in drivers/usb/host.

Alan Stern

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