linux-kernel - Re: [GIT pull] irq updates for 4.13

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Date:   Mon, 10 Jul 2017 22:15:03 +0200
From:   Sebastian Reichel <sebastian.reichel@...labora.co.uk>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ingo Molnar <mingo@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>, Tony Lindgren <tony@...mide.com>,
        Pavel Machek <pavel@....cz>
Subject: Re: [GIT pull] irq updates for 4.13

Hi Linus,

On Mon, Jul 10, 2017 at 10:01:22AM -0700, Linus Torvalds wrote:
> On Mon, Jul 10, 2017 at 6:35 AM, Sebastian Reichel
> <sebastian.reichel@...labora.co.uk> wrote:
> >
> > This patch apparently breaks OMAP platform:
> >
> > 46e48e257360f0845fe17089713cbad4db611e70 is the first bad commit
> > commit 46e48e257360f0845fe17089713cbad4db611e70
> > Author: Thomas Gleixner <tglx@...utronix.de>
> > Date:   Thu Jun 29 23:33:38 2017 +0200
> >
> >     genirq: Move irq resource handling out of spinlocked region
> >
> > Boot failure log from Droid 4:
> > [ ... snip snip ..]
> >
> > Droid 4 boots current master again after applying the patch below
> > (which is git revet of above patch, but I provide the patch, since
> > it did not revet cleanly).
> 
> Hmm. Do you actually need the full revert?

It's technically not a full revert - I actually did not revert the
__free_irq changes.

> I think it's only the __setup_irq() part that looks like it may be garbage.
> 
> For example, I think it releases the resources twice if the
> __irq_set_trigger() call fails.
> 
> But it looks questionably in other ways too - notably, the change to
> make the request call be in the same context as the freeing is done is
> apparently done entirely for symmetry reasons, not for any actual
> *reason* reasons.
> 
> So I suspect just the __setup_irq() parts should be reverted, because
> they look both buggy and pointless. But the actual *real* part of the
> patch was the two-liner __free_irq() part, and that looks sane to me.
> 
> So Sebastian, can you test if it's ok to revert just the __setup_irq()
> part, but leave the smaller part in __free_irq() that just moves the
> irq_release_resources() around at freeing time?

Looking at my patch it implements what you describe (by coincidence,
since git revert could not do a clean revert) as far as I can see.
It seems Pavel also understood it this way, since his patch is identical 
to the one I provided.

-- Sebastian

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