Messages in this thread | | | Date | Fri, 2 Dec 2016 11:00:48 -0600 (CST) | From | Aaron Sierra <> | Subject | Re: [PATCH] acpi/rt: convert acpi_gbl_gpe_lock to raw spinlock |
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----- Original Message ----- > From: "Thomas Gleixner" <tglx@linutronix.de> > Sent: Thursday, December 1, 2016 5:21:20 PM
> On Thu, 1 Dec 2016, Aaron Sierra wrote: >> ----- Original Message ----- >> > From: "Thomas Gleixner" <tglx@linutronix.de> >> > Sent: Thursday, December 1, 2016 8:52:48 AM >> >> > On Wed, 30 Nov 2016, Aaron Sierra wrote: >> >> When testing GPE interrupts with CONFIG_PREEMPT_RT_FULL enabled, a >> >> verbose WARN_ONCE message would print to the kernel log. It turned out >> >> that the GPE interrupt handler was being called with local interrupts >> >> enabled because acpi_gbl_gpe_lock was implemented as a spinlock_t. Full >> >> preemption strips local interrupt disabling from spinlock_t operations, >> >> but not for raw_spinlock_t operations. >> >> >> >> This is the warning that was triggered: >> >> >> >> ------------[ cut here ]------------ >> >> WARNING: CPU: 8 PID: 483 at kernel/irq/handle.c:149 >> >> __handle_irq_event_percpu+0x6f/0xcf >> >> irq 33 handler irq_default_primary_handler+0x0/0xb enabled interrupts >> >> Modules linked in: gpio_irq_demo(O) >> >> CPU: 8 PID: 483 Comm: irq/9-acpi Tainted: G O >> >> 4.8.6-rt5-00012-geaa3b7c #6 >> >> Hardware name: Extreme Engineering Solutions, Inc. XCalibur4643/XCalibur4643, >> >> BIOS 1-1.1.12.3_Alpha 04/29/2016 >> >> 0000000000000000 ffff880858f3bc10 ffffffff81219a93 ffff880858f3bc60 >> >> 0000000000000000 ffff880858f3bc50 ffffffff8104b84a 0000009500000000 >> >> ffff880855b76880 0000000000000021 0000000000000002 ffff880856356800 >> >> Call Trace: >> >> [<ffffffff81219a93>] dump_stack+0x4d/0x63 >> >> [<ffffffff8104b84a>] __warn+0xc0/0xdb >> >> [<ffffffff8104b8af>] warn_slowpath_fmt+0x4a/0x4c >> >> [<ffffffff810f7192>] ? path_openat+0xbf8/0xc62 >> >> [<ffffffff8107d7c3>] ? handle_irq_event+0x75/0x75 >> >> [<ffffffff8107d68d>] __handle_irq_event_percpu+0x6f/0xcf >> >> [<ffffffff8107d727>] handle_irq_event_percpu+0x3a/0x61 >> >> [<ffffffff8107d7a3>] handle_irq_event+0x55/0x75 >> >> [<ffffffff8107ff76>] handle_simple_irq+0x5c/0x92 >> >> [<ffffffff81243a53>] gpe_irq_handler+0x2a/0x31 >> > >> > gpe_irq_handler is not in tree, so I really cannot tell what this is >> > about. It looks like it does interrupt demultiplexing, which triggers the >> > warning. >> >> Thomas, >> Your guess is correct, this involves a currently out-of-tree extension to >> the gpio-ich driver which allows GPIO pins to be mapped to IRQs by demuxing >> their corresponding GPE events. >> The gpio_irq_demo module requests a GPIO pin, converts it to an IRQ using >> gpio_to_irq() and registers a trivial handler against the IRQ. > > So the simple solution is in the demux handler: > > gpe_irq_handler() > { > + local_irq_save(flags); > > for_each_pending_gpio_irq(irq) > generic_handle_irq(irq); > > + local_irq_restore(flags); > }
Thomas, Yes, of course. That's how I initially worked around my problem before digging into the ACPI subsystem. I just didn't believe that was anything more than a workaround, so I went looking for a more "correct" solution. I don't have a problem maintaining this for myself if it isn't generally useful.
-Aaron S.
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