Re: [PATCH 2/2] pinctrl: intel: Prevent force threading of the interrupt handler

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Thu, Jun 16, 2016 at 10:25 AM, Mika Westerberg
<mika.westerberg@xxxxxxxxxxxxxxx> wrote:

> The pinctrl-intel needs to use request_irq() instead of chained interrupt
> handling because it shares the interrupt with multiple GPIO host
> controllers found on Intel CPUs. In -rt all such interrupts are forced to
> run in thread context which triggers following warning:
>
>  WARNING: CPU: 0 PID: 530 at kernel/irq/handle.c:151 handle_irq_event_percpu+0x23d/0x240
>  irq 348 handler irq_default_primary_handler+0x0/0x10 enabled interrupts
>  Modules linked in:
>  CPU: 0 PID: 530 Comm: irq/14-INT3452: Not tainted 4.6.2-rt5 #1060
>   0000000000000000 ffff88007a257c98 ffffffff812d8494 ffff88007a257ce8
>   0000000000000000 ffff88007a257cd8 ffffffff8105e554 000000977a257d90
>   ffff88007a37a380 000000000000015c 0000000000000002 0000000000000000
>  Call Trace:
>   [<ffffffff812d8494>] dump_stack+0x4f/0x6b
>   [<ffffffff8105e554>] __warn+0xe4/0x100
>   [<ffffffff8105e5bf>] warn_slowpath_fmt+0x4f/0x60
>   [<ffffffff810b18f0>] ? __synchronize_hardirq+0x60/0x60
>   [<ffffffff810b17fd>] handle_irq_event_percpu+0x23d/0x240
>   [<ffffffff810b1862>] handle_irq_event+0x62/0x90
>   [<ffffffff810b4e1f>] handle_edge_irq+0x8f/0x190
>   [<ffffffff810b0d82>] generic_handle_irq+0x22/0x30
>   [<ffffffff81307abc>] intel_gpio_irq+0xdc/0x150
>   [<ffffffff810b2293>] irq_forced_thread_fn+0x23/0x70
>   [<ffffffff810b250b>] irq_thread+0x13b/0x1d0
>   [<ffffffff8167b844>] ? __schedule+0x2e4/0x5a0
>   [<ffffffff810b2270>] ? irq_finalize_oneshot.part.37+0xd0/0xd0
>   [<ffffffff810b25a0>] ? irq_thread+0x1d0/0x1d0
>   [<ffffffff810b23d0>] ? wake_threads_waitq+0x30/0x30
>   [<ffffffff8107e624>] kthread+0xd4/0xf0
>   [<ffffffff8167ec27>] ? _raw_spin_unlock_irq+0x17/0x40
>   [<ffffffff8167f592>] ret_from_fork+0x22/0x40
>   [<ffffffff8107e550>] ? kthread_worker_fn+0x190/0x190
>
> The handle_irq_event_* functions (and I suppose generic_handle_irq()) is
> expected to be called with interrupts disabled and they rightfully complain
> here because we run in thread context with interrupts enabled.
>
> Fix this by adding IRQF_NO_THREAD flag when the master interrupt is
> requested. This prevents forced threading of the interrupt used by the GPIO
> host controllers.
>
> Reported-by: Kim Tatt Chuah <kim.tatt.chuah@xxxxxxxxx>
> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>

Patch applied.

Yours,
Linus Walleij
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