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

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Date:   Mon, 10 Jul 2017 21:38:56 +0200
From:   Pavel Machek <pavel@....cz>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Sebastian Reichel <sebastian.reichel@...labora.co.uk>,
        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>
Subject: Re: [GIT pull] irq updates for 4.13

Hi!

> > 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?
> 
> 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?

If I understood it correctly, you wanted to test this:

And yes, this is enough to fix boot on N900 for me.

Thanks,
								Pavel

commit 285358d48dec82f13fa76724bff434897883d188
Author: Pavel <pavel@....cz>
Date:   Mon Jul 10 21:35:25 2017 +0200

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 5624b2d..528bfc3 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1168,14 +1168,6 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 		new->flags &= ~IRQF_ONESHOT;
 
 	mutex_lock(&desc->request_mutex);
-	if (!desc->action) {
-		ret = irq_request_resources(desc);
-		if (ret) {
-			pr_err("Failed to request resources for %s (irq %d) on irqchip %s\n",
-			       new->name, irq, desc->irq_data.chip->name);
-			goto out_mutex;
-		}
-	}
 
 	chip_bus_lock(desc);
 
@@ -1279,6 +1271,13 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 	}
 
 	if (!shared) {
+		ret = irq_request_resources(desc);
+		if (ret) {
+			pr_err("Failed to request resources for %s (irq %d) on irqchip %s\n",
+			       new->name, irq, desc->irq_data.chip->name);
+			goto out_unlock;
+		}
+
 		init_waitqueue_head(&desc->wait_for_threads);
 
 		/* Setup the type (level, edge polarity) if configured: */
@@ -1387,10 +1386,6 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 
 	chip_bus_sync_unlock(desc);
 
-	if (!desc->action)
-		irq_release_resources(desc);
-
-out_mutex:
 	mutex_unlock(&desc->request_mutex);
 
 out_thread:


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

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