linux-kernel - Re: [PATCH 0/5] Fix regression introduced by set_irq

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Message-ID: <20151020140427.GE3953@io.lakedaemon.net>
Date:	Tue, 20 Oct 2015 14:04:27 +0000
From:	Jason Cooper <jason@...edaemon.net>
To:	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Marc Zyngier <marc.zyngier@....com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Tawfik Bayouk <tawfik@...vell.com>,
	Nadav Haklai <nadavh@...vell.com>,
	Lior Amsalem <alior@...vell.com>, Andrew Lunn <andrew@...n.ch>,
	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
	Gregory Clement <gregory.clement@...e-electrons.com>
Subject: Re: [PATCH 0/5] Fix regression introduced by set_irq_flags() removal

Thomas (tglx also),

On Tue, Oct 20, 2015 at 03:23:50PM +0200, Thomas Petazzoni wrote:
> Thomas, Jason, Marc, Rob,
> 
> In commit d17cab4451df ("irqchip: Kill off set_irq_flags usage"), Rob
> Herring modified the irqchip drivers to not use the ARM-specific
> set_irq_flags() and instead rely on various functions provided by the
> core irq subsystem.
> 
> While his commit was supposed to have no functional effect, it in fact
> does have one effect: the IRQ_NOAUTOEN flag used to be *cleared* for
> all interrupts and it is now *set* by default.
> 
> Thanks to this flag being *cleared* by default, the irq-armada-370-xp
> was able to properly re-enable per-CPU interrupts at resume time. Now
> that this flag is *set*, the irqd_irq_disabled() function no longer
> indicates that such per-CPU interrupts are enabled (and in fact a
> CPU-global flag to tell whether a per-CPU is enabled or not is
> silly). Due to this, our local timer per-CPU interrupt is no longer
> re-enabled at resume time on Armada XP, on the boot CPU, which causes
> a hang at resume time.
> 
> This is a regression between 4.2 (where suspend/resume works fine) and
> 4.3-rc (where suspend/resume is broken). Reverting d17cab4451df1 on
> top of 4.3-rc makes the problem go away (of course you also need to
> revert eb811129ed9ea so that set_irq_flags is re-introduced).
> 
> The minimal fix would be to clear the IRQ_NOAUTOEN flag so that we get
> back to the original situation. However, this does not really seem
> like the right fix.
> 
> Instead, this patch series proposes to add an is_enabled_percpu_irq()
> function to the core irq subsystem, which is then used by the
> irq-armada-370-xp to find out if such or such per-CPU interrupt should
> be re-enabled at resume time on the boot CPU.
> 
> The organization of the patch series is as follows:
> 
>  - PATCH 1 introduces the is_enabled_percpu_irq() function.
> 
>  - PATCH 2 does a minor refactoring of armada_xp_mpic_secondary_init()
>    to prepare the following patch.
> 
>  - PATCH 3 changes the irq-armada-370-xp driver to use the
>    is_enabled_percpu_irq() to re-enable the per-CPU interrupts on the
>    boot CPU at resume time, and also modifies the secondary CPU
>    notifier to re-enable per-CPU interrupts if needed.
> 
>  - PATCH 4 and 5 are further cleanups/improvements to the
>    irq-armada-370-xp, which are not needed to fix the problem.
> 
> Since this is fixing a regression introduced between 4.2 and 4.3-rc,
> it would be great if patches 1 to 3 could be merged in 4.3. The last
> two patches are only cosmetic, so merging them for 4.4 is of course
> the way to go.
> 
> Thanks,
> 
> Thomas
> 
> Thomas Petazzoni (5):
>   kernel: irq: implement is_enabled_percpu_irq()
>   irqchip: armada-370-xp: prepare additions to
>     armada_xp_mpic_secondary_init()
>   irqchip: armada-370-xp: re-enable per-CPU interrupts at resume time
>   irqchip: armada-370-xp: re-order register definitions
>   irqchip: armada-370-xp: document the overall driver logic
> 
>  drivers/irqchip/irq-armada-370-xp.c | 151 +++++++++++++++++++++++++++++++-----
>  include/linux/interrupt.h           |   1 +
>  kernel/irq/chip.c                   |   5 ++
>  kernel/irq/internals.h              |   1 +
>  kernel/irq/manage.c                 |  19 +++++
>  5 files changed, 158 insertions(+), 19 deletions(-)

Whole series,

Reviewed by: Jason Cooper <jason@...edaemon.net>


Thomas (tglx), if you're happy with the core changes, let me know and
I'll cue the series up.

We know it's a bit late in the -rc cycle, but the alternative (reverting
Rob's patch) would likely be more destabilizing at this point.

thx,

Jason.
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