linux-kernel - Re: [PATCH v2] Do not mark ACPI devices as irq safe

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Message-ID: <CAHp75VcLR5ehrCyVsY0TKWSogRt-_ETqkZ1VE=ATVqRc8Y_9vg@mail.gmail.com>
Date: Tue, 13 Aug 2024 22:45:07 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Breno Leitao <leitao@...ian.org>
Cc: Laxman Dewangan <ldewangan@...dia.com>, Dmitry Osipenko <digetx@...il.com>, 
	Andi Shyti <andi.shyti@...nel.org>, Thierry Reding <thierry.reding@...il.com>, 
	Jonathan Hunter <jonathanh@...dia.com>, leit@...a.com, 
	Michael van der Westhuizen <rmikey@...a.com>, Andy Shevchenko <andy@...nel.org>, 
	"open list:I2C SUBSYSTEM HOST DRIVERS" <linux-i2c@...r.kernel.org>, 
	"open list:TEGRA ARCHITECTURE SUPPORT" <linux-tegra@...r.kernel.org>, open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] Do not mark ACPI devices as irq safe

On Tue, Aug 13, 2024 at 7:13 PM Breno Leitao <leitao@...ian.org> wrote:
>
> On ACPI machines, the tegra i2c module encounters an issue due to a
> mutex being called inside a spinlock. This leads to the following bug:
>
>         BUG: sleeping function called from invalid context at kernel/locking/mutex.c:585
>         in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 1282, name: kssif0010
>         preempt_count: 0, expected: 0
>         RCU nest depth: 0, expected: 0
>         irq event stamp: 0
>
>         Call trace:
>         __might_sleep
>         __mutex_lock_common
>         mutex_lock_nested
>         acpi_subsys_runtime_resume
>         rpm_resume
>         tegra_i2c_xfer

The above stacktrace is still too verbose. Submitting Patches
documentation is clear about this. Please, remove unrelated,
insignificant lines, like
"irq event stamp: 0" which gives no valuable information. So, at the
end it will be ~5-6 lines only. Other than that, LGTM.

> The problem arises because during __pm_runtime_resume(), the spinlock
> &dev->power.lock is acquired before rpm_resume() is called. Later,
> rpm_resume() invokes acpi_subsys_runtime_resume(), which relies on
> mutexes, triggering the error.
>
> To address this issue, devices on ACPI are now marked as not IRQ-safe,
> considering the dependency of acpi_subsys_runtime_resume() on mutexes.

-- 
With Best Regards,
Andy Shevchenko