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

[Andy Shevchenko]

On Tue, Aug 13, 2024 at 7:13 PM Breno Leitao <leitao@xxxxxxxxxx> 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