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SubjectRe: [PATCH] gpio: use raw spinlock for gpio chip shadowed data
On Sat, Apr 16, 2022 at 3:45 AM Schspa Shi <schspa@gmail.com> wrote:
>
> In case of PREEMPT_RT, there is a raw_spinlock -> spinlock dependency
> as the lockdep report shows.
>
> __irq_set_handler
> irq_get_desc_buslock
> __irq_get_desc_lock
> raw_spin_lock_irqsave(&desc->lock, *flags); // raw spinlock get here
> __irq_do_set_handler
> mask_ack_irq
> dwapb_irq_ack
> spin_lock_irqsave(&gc->bgpio_lock, flags); // sleep able spinlock
> irq_put_desc_busunlock
>
> Replace with a raw lock to avoid BUGs. This lock is only used to access
> registers, and It's safe to replace with the raw lock without bad
> influence.

> [ 15.090359][ T1] =============================
> [ 15.090365][ T1] [ BUG: Invalid wait context ]
> [ 15.090373][ T1] 5.10.59-rt52-00983-g186a6841c682-dirty #3 Not tainted
> [ 15.090386][ T1] -----------------------------

Please, reduce this very noise traceback to the point, usually it
takes ~3-5 lines only.

...

> drivers/gpio/gpio-amdpt.c | 10 +++----
> drivers/gpio/gpio-brcmstb.c | 12 ++++----
> drivers/gpio/gpio-cadence.c | 12 ++++----
> drivers/gpio/gpio-dwapb.c | 36 +++++++++++------------
> drivers/gpio/gpio-grgpio.c | 30 +++++++++----------
> drivers/gpio/gpio-hlwd.c | 18 ++++++------
> drivers/gpio/gpio-idt3243x.c | 12 ++++----
> drivers/gpio/gpio-ixp4xx.c | 4 +--
> drivers/gpio/gpio-loongson1.c | 8 ++---
> drivers/gpio/gpio-menz127.c | 8 ++---
> drivers/gpio/gpio-mlxbf2.c | 18 ++++++------
> drivers/gpio/gpio-mmio.c | 22 +++++++-------
> drivers/gpio/gpio-sifive.c | 12 ++++----
> drivers/gpio/gpio-tb10x.c | 4 +--
> drivers/pinctrl/nuvoton/pinctrl-npcm7xx.c | 8 ++---
> include/linux/gpio/driver.h | 2 +-

Looking into the code I think we can't easily (without too much
additional churn) to split this to the series of patches. But I leave
this up to the maintainers to decide.

--
With Best Regards,
Andy Shevchenko

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