From mboxrd@z Thu Jan 1 00:00:00 1970 From: boris.brezillon@free-electrons.com (Boris Brezillon) Date: Thu, 26 Feb 2015 09:06:13 +0100 Subject: [RFC PATCH 1/3] genirq: prevent system wakeup when dealing with IRQF_NO_SUSPEND IRQs In-Reply-To: <1721977.3MjzADDQbj@vostro.rjw.lan> References: <1424771762-16343-1-git-send-email-boris.brezillon@free-electrons.com> <1424771762-16343-2-git-send-email-boris.brezillon@free-electrons.com> <1721977.3MjzADDQbj@vostro.rjw.lan> Message-ID: <20150226090613.465c95a9@bbrezillon> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, 25 Feb 2015 23:01:31 +0100 "Rafael J. Wysocki" wrote: > On Tuesday, February 24, 2015 10:56:00 AM Boris Brezillon wrote: > > Mixing IRQF_NO_SUSPEND and !IRQF_NO_SUSPEND on the same IRQ line is highly > > discouraged, but in some cases (IRQ shared by a timer and other devices) > > you don't have any other choice. > > Since some devices sharing the IRQ line might tag it as a wakeup source, > > you might end up with your handler that requested IRQF_NO_SUSPEND not > > being called in suspended state, or invalid system wakeup (the system is > > woken up without any wakeup source actually requesting it). > > > > To deal with such unlikely situations, you'll have to: > > 1/ prevent any automatic wakeup when at least one of the IRQ users > > registered with IRQF_NO_SUSPEND > > 2/ let IRQ users decide if/when they should wake the system up > > > > This patch is taking care of 1. > > > > Signed-off-by: Boris Brezillon > > --- > > kernel/irq/pm.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/kernel/irq/pm.c b/kernel/irq/pm.c > > index 3ca5325..1743162 100644 > > --- a/kernel/irq/pm.c > > +++ b/kernel/irq/pm.c > > @@ -16,7 +16,8 @@ > > > > bool irq_pm_check_wakeup(struct irq_desc *desc) > > { > > - if (irqd_is_wakeup_armed(&desc->irq_data)) { > > + if (irqd_is_wakeup_armed(&desc->irq_data) && > > + !desc->no_suspend_depth) { > > irqd_clear(&desc->irq_data, IRQD_WAKEUP_ARMED); > > desc->istate |= IRQS_SUSPENDED | IRQS_PENDING; > > desc->depth++; > > > > I'm not sure how this helps, because irqd_is_wakeup_armed() is false for > IRQs having no_suspend_depth different from zero (please see the first > check in suspend_device_irq()). > > Indeed, it seems I overlooked this test in suspend_device_irq, and this makes my irq_is_wakeup_armed test useless. -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com