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Date:   Wed, 20 Apr 2022 12:37:28 +0300
From:   Serge Semin <fancer.lancer@gmail.com>
To:     Schspa Shi <schspa@gmail.com>
Cc:     Serge Semin <Sergey.Semin@baikalelectronics.ru>, brgl@bgdev.pl,
        andy.shevchenko@gmail.com, linus.walleij@linaro.org,
        f.fainelli@gmail.com, hoan@os.amperecomputing.com,
        linux-arm-kernel@lists.infradead.org, linux-gpio@vger.kernel.org,
        linux-kernel@vger.kernel.org, opendmb@gmail.com
Subject: Re: [PATCH v3] gpio: use raw spinlock for gpio chip shadowed data
Message-ID: <20220420093728.yzsiozkwdjn3jbbc@mobilestation>
References: <CAMRc=Meo4TbdxQzynb7paDgC7J19Tc6hhKU7du4mZvgP0mynTQ@mail.gmail.com>
 <20220419012810.88417-1-schspa@gmail.com>
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On Tue, Apr 19, 2022 at 09:28:10AM +0800, Schspa Shi 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] -----------------------------
> [   15.090392][    T1] swapper/0/1 is trying to lock:
> [   15.090402][    T1] 70ff00018507c188 (&gc->bgpio_lock){....}-{3:3}, at: _raw_spin_lock_irqsave+0x1c/0x28
> [   15.090470][    T1] other info that might help us debug this:
> [   15.090477][    T1] context-{5:5}
> [   15.090485][    T1] 3 locks held by swapper/0/1:
> [   15.090497][    T1]  #0: c2ff0001816de1a0 (&dev->mutex){....}-{4:4}, at: __device_driver_lock+0x98/0x104
> [   15.090553][    T1]  #1: ffff90001485b4b8 (irq_domain_mutex){+.+.}-{4:4}, at: irq_domain_associate+0xbc/0x6d4
> [   15.090606][    T1]  #2: 4bff000185d7a8e0 (lock_class){....}-{2:2}, at: _raw_spin_lock_irqsave+0x1c/0x28
> [   15.090654][    T1] stack backtrace:
> [   15.090661][    T1] CPU: 4 PID: 1 Comm: swapper/0 Not tainted 5.10.59-rt52-00983-g186a6841c682-dirty #3
> [   15.090682][    T1] Hardware name: Horizon Robotics Journey 5 DVB (DT)
> [   15.090692][    T1] Call trace:
> ......
> [   15.090811][    T1]  _raw_spin_lock_irqsave+0x1c/0x28
> [   15.090828][    T1]  dwapb_irq_ack+0xb4/0x300
> [   15.090846][    T1]  __irq_do_set_handler+0x494/0xb2c
> [   15.090864][    T1]  __irq_set_handler+0x74/0x114
> [   15.090881][    T1]  irq_set_chip_and_handler_name+0x44/0x58
> [   15.090900][    T1]  gpiochip_irq_map+0x210/0x644
> 
> Signed-off-by: Schspa Shi <schspa@gmail.com>
> 
> ---
> 
> Changelog:
> v1 -> v2:
>         - Reduce the useless stacktrace.
>         - Split to series of patches
> v2 -> v3:
>         - Restore to a single patch as Andy and Bartosz's suggest
>         - add cutter ‘--- ‘ line for Change log
> ---
>  drivers/gpio/gpio-amdpt.c                 | 10 +++----
>  drivers/gpio/gpio-brcmstb.c               | 12 ++++----
>  drivers/gpio/gpio-cadence.c               | 12 ++++----

>  drivers/gpio/gpio-dwapb.c                 | 36 +++++++++++------------

for the dwapb-gpio.c driver:
Acked-by: Serge Semin <fancer.lancer@gmail.com>

-Sergey

>  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 +-
>  16 files changed, 108 insertions(+), 108 deletions(-)
> 

[...]

> diff --git a/drivers/gpio/gpio-dwapb.c b/drivers/gpio/gpio-dwapb.c
> index b0f3aca61974..7130195da48d 100644
> --- a/drivers/gpio/gpio-dwapb.c
> +++ b/drivers/gpio/gpio-dwapb.c
> @@ -243,9 +243,9 @@ static void dwapb_irq_ack(struct irq_data *d)
>  	u32 val = BIT(irqd_to_hwirq(d));
>  	unsigned long flags;
>  
> -	spin_lock_irqsave(&gc->bgpio_lock, flags);
> +	raw_spin_lock_irqsave(&gc->bgpio_lock, flags);
>  	dwapb_write(gpio, GPIO_PORTA_EOI, val);
> -	spin_unlock_irqrestore(&gc->bgpio_lock, flags);
> +	raw_spin_unlock_irqrestore(&gc->bgpio_lock, flags);
>  }
>  
>  static void dwapb_irq_mask(struct irq_data *d)
> @@ -255,10 +255,10 @@ static void dwapb_irq_mask(struct irq_data *d)
>  	unsigned long flags;
>  	u32 val;
>  
> -	spin_lock_irqsave(&gc->bgpio_lock, flags);
> +	raw_spin_lock_irqsave(&gc->bgpio_lock, flags);
>  	val = dwapb_read(gpio, GPIO_INTMASK) | BIT(irqd_to_hwirq(d));
>  	dwapb_write(gpio, GPIO_INTMASK, val);
> -	spin_unlock_irqrestore(&gc->bgpio_lock, flags);
> +	raw_spin_unlock_irqrestore(&gc->bgpio_lock, flags);
>  }
>  
>  static void dwapb_irq_unmask(struct irq_data *d)
> @@ -268,10 +268,10 @@ static void dwapb_irq_unmask(struct irq_data *d)
>  	unsigned long flags;
>  	u32 val;
>  
> -	spin_lock_irqsave(&gc->bgpio_lock, flags);
> +	raw_spin_lock_irqsave(&gc->bgpio_lock, flags);
>  	val = dwapb_read(gpio, GPIO_INTMASK) & ~BIT(irqd_to_hwirq(d));
>  	dwapb_write(gpio, GPIO_INTMASK, val);
> -	spin_unlock_irqrestore(&gc->bgpio_lock, flags);
> +	raw_spin_unlock_irqrestore(&gc->bgpio_lock, flags);
>  }
>  
>  static void dwapb_irq_enable(struct irq_data *d)
> @@ -281,11 +281,11 @@ static void dwapb_irq_enable(struct irq_data *d)
>  	unsigned long flags;
>  	u32 val;
>  
> -	spin_lock_irqsave(&gc->bgpio_lock, flags);
> +	raw_spin_lock_irqsave(&gc->bgpio_lock, flags);
>  	val = dwapb_read(gpio, GPIO_INTEN);
>  	val |= BIT(irqd_to_hwirq(d));
>  	dwapb_write(gpio, GPIO_INTEN, val);
> -	spin_unlock_irqrestore(&gc->bgpio_lock, flags);
> +	raw_spin_unlock_irqrestore(&gc->bgpio_lock, flags);
>  }
>  
>  static void dwapb_irq_disable(struct irq_data *d)
> @@ -295,11 +295,11 @@ static void dwapb_irq_disable(struct irq_data *d)
>  	unsigned long flags;
>  	u32 val;
>  
> -	spin_lock_irqsave(&gc->bgpio_lock, flags);
> +	raw_spin_lock_irqsave(&gc->bgpio_lock, flags);
>  	val = dwapb_read(gpio, GPIO_INTEN);
>  	val &= ~BIT(irqd_to_hwirq(d));
>  	dwapb_write(gpio, GPIO_INTEN, val);
> -	spin_unlock_irqrestore(&gc->bgpio_lock, flags);
> +	raw_spin_unlock_irqrestore(&gc->bgpio_lock, flags);
>  }
>  
>  static int dwapb_irq_set_type(struct irq_data *d, u32 type)
> @@ -309,7 +309,7 @@ static int dwapb_irq_set_type(struct irq_data *d, u32 type)
>  	irq_hw_number_t bit = irqd_to_hwirq(d);
>  	unsigned long level, polarity, flags;
>  
> -	spin_lock_irqsave(&gc->bgpio_lock, flags);
> +	raw_spin_lock_irqsave(&gc->bgpio_lock, flags);
>  	level = dwapb_read(gpio, GPIO_INTTYPE_LEVEL);
>  	polarity = dwapb_read(gpio, GPIO_INT_POLARITY);
>  
> @@ -344,7 +344,7 @@ static int dwapb_irq_set_type(struct irq_data *d, u32 type)
>  	dwapb_write(gpio, GPIO_INTTYPE_LEVEL, level);
>  	if (type != IRQ_TYPE_EDGE_BOTH)
>  		dwapb_write(gpio, GPIO_INT_POLARITY, polarity);
> -	spin_unlock_irqrestore(&gc->bgpio_lock, flags);
> +	raw_spin_unlock_irqrestore(&gc->bgpio_lock, flags);
>  
>  	return 0;
>  }
> @@ -374,7 +374,7 @@ static int dwapb_gpio_set_debounce(struct gpio_chip *gc,
>  	unsigned long flags, val_deb;
>  	unsigned long mask = BIT(offset);
>  
> -	spin_lock_irqsave(&gc->bgpio_lock, flags);
> +	raw_spin_lock_irqsave(&gc->bgpio_lock, flags);
>  
>  	val_deb = dwapb_read(gpio, GPIO_PORTA_DEBOUNCE);
>  	if (debounce)
> @@ -383,7 +383,7 @@ static int dwapb_gpio_set_debounce(struct gpio_chip *gc,
>  		val_deb &= ~mask;
>  	dwapb_write(gpio, GPIO_PORTA_DEBOUNCE, val_deb);
>  
> -	spin_unlock_irqrestore(&gc->bgpio_lock, flags);
> +	raw_spin_unlock_irqrestore(&gc->bgpio_lock, flags);
>  
>  	return 0;
>  }
> @@ -738,7 +738,7 @@ static int dwapb_gpio_suspend(struct device *dev)
>  	unsigned long flags;
>  	int i;
>  
> -	spin_lock_irqsave(&gc->bgpio_lock, flags);
> +	raw_spin_lock_irqsave(&gc->bgpio_lock, flags);
>  	for (i = 0; i < gpio->nr_ports; i++) {
>  		unsigned int offset;
>  		unsigned int idx = gpio->ports[i].idx;
> @@ -765,7 +765,7 @@ static int dwapb_gpio_suspend(struct device *dev)
>  			dwapb_write(gpio, GPIO_INTMASK, ~ctx->wake_en);
>  		}
>  	}
> -	spin_unlock_irqrestore(&gc->bgpio_lock, flags);
> +	raw_spin_unlock_irqrestore(&gc->bgpio_lock, flags);
>  
>  	clk_bulk_disable_unprepare(DWAPB_NR_CLOCKS, gpio->clks);
>  
> @@ -785,7 +785,7 @@ static int dwapb_gpio_resume(struct device *dev)
>  		return err;
>  	}
>  
> -	spin_lock_irqsave(&gc->bgpio_lock, flags);
> +	raw_spin_lock_irqsave(&gc->bgpio_lock, flags);
>  	for (i = 0; i < gpio->nr_ports; i++) {
>  		unsigned int offset;
>  		unsigned int idx = gpio->ports[i].idx;
> @@ -812,7 +812,7 @@ static int dwapb_gpio_resume(struct device *dev)
>  			dwapb_write(gpio, GPIO_PORTA_EOI, 0xffffffff);
>  		}
>  	}
> -	spin_unlock_irqrestore(&gc->bgpio_lock, flags);
> +	raw_spin_unlock_irqrestore(&gc->bgpio_lock, flags);
>  
>  	return 0;
>  }

[...]