[PATCH 3/5] gpio: cdev: update flags at once when reconfiguring from user-space

From: Bartosz Golaszewski
Date: Fri Oct 04 2024 - 10:45:11 EST


From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>

Make updating the descriptor flags when reconfiguring from user-space
consistent with the rest of the codebase: read the current state
atomically, update it according to user's instructions and write it back
atomically as well.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
---
drivers/gpio/gpiolib-cdev.c | 70 +++++++++++++++++++++++++--------------------
1 file changed, 39 insertions(+), 31 deletions(-)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 6113a283c34a..b0050250ac3a 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -143,18 +143,22 @@ static int linehandle_validate_flags(u32 flags)

static void linehandle_flags_to_desc_flags(u32 lflags, unsigned long *flagsp)
{
- assign_bit(FLAG_ACTIVE_LOW, flagsp,
+ unsigned long flags = READ_ONCE(*flagsp);
+
+ assign_bit(FLAG_ACTIVE_LOW, &flags,
lflags & GPIOHANDLE_REQUEST_ACTIVE_LOW);
- assign_bit(FLAG_OPEN_DRAIN, flagsp,
+ assign_bit(FLAG_OPEN_DRAIN, &flags,
lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN);
- assign_bit(FLAG_OPEN_SOURCE, flagsp,
+ assign_bit(FLAG_OPEN_SOURCE, &flags,
lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE);
- assign_bit(FLAG_PULL_UP, flagsp,
+ assign_bit(FLAG_PULL_UP, &flags,
lflags & GPIOHANDLE_REQUEST_BIAS_PULL_UP);
- assign_bit(FLAG_PULL_DOWN, flagsp,
+ assign_bit(FLAG_PULL_DOWN, &flags,
lflags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN);
- assign_bit(FLAG_BIAS_DISABLE, flagsp,
+ assign_bit(FLAG_BIAS_DISABLE, &flags,
lflags & GPIOHANDLE_REQUEST_BIAS_DISABLE);
+
+ WRITE_ONCE(*flagsp, flags);
}

static long linehandle_set_config(struct linehandle_state *lh,
@@ -1348,38 +1352,42 @@ static int gpio_v2_line_config_validate(struct gpio_v2_line_config *lc,
return 0;
}

-static void gpio_v2_line_config_flags_to_desc_flags(u64 flags,
+static void gpio_v2_line_config_flags_to_desc_flags(u64 lflags,
unsigned long *flagsp)
{
- assign_bit(FLAG_ACTIVE_LOW, flagsp,
- flags & GPIO_V2_LINE_FLAG_ACTIVE_LOW);
+ unsigned long flags = READ_ONCE(*flagsp);

- if (flags & GPIO_V2_LINE_FLAG_OUTPUT)
- set_bit(FLAG_IS_OUT, flagsp);
- else if (flags & GPIO_V2_LINE_FLAG_INPUT)
- clear_bit(FLAG_IS_OUT, flagsp);
+ assign_bit(FLAG_ACTIVE_LOW, &flags,
+ lflags & GPIO_V2_LINE_FLAG_ACTIVE_LOW);

- assign_bit(FLAG_EDGE_RISING, flagsp,
- flags & GPIO_V2_LINE_FLAG_EDGE_RISING);
- assign_bit(FLAG_EDGE_FALLING, flagsp,
- flags & GPIO_V2_LINE_FLAG_EDGE_FALLING);
+ if (lflags & GPIO_V2_LINE_FLAG_OUTPUT)
+ set_bit(FLAG_IS_OUT, &flags);
+ else if (lflags & GPIO_V2_LINE_FLAG_INPUT)
+ clear_bit(FLAG_IS_OUT, &flags);

- assign_bit(FLAG_OPEN_DRAIN, flagsp,
- flags & GPIO_V2_LINE_FLAG_OPEN_DRAIN);
- assign_bit(FLAG_OPEN_SOURCE, flagsp,
- flags & GPIO_V2_LINE_FLAG_OPEN_SOURCE);
+ assign_bit(FLAG_EDGE_RISING, &flags,
+ lflags & GPIO_V2_LINE_FLAG_EDGE_RISING);
+ assign_bit(FLAG_EDGE_FALLING, &flags,
+ lflags & GPIO_V2_LINE_FLAG_EDGE_FALLING);

- assign_bit(FLAG_PULL_UP, flagsp,
- flags & GPIO_V2_LINE_FLAG_BIAS_PULL_UP);
- assign_bit(FLAG_PULL_DOWN, flagsp,
- flags & GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN);
- assign_bit(FLAG_BIAS_DISABLE, flagsp,
- flags & GPIO_V2_LINE_FLAG_BIAS_DISABLED);
+ assign_bit(FLAG_OPEN_DRAIN, &flags,
+ lflags & GPIO_V2_LINE_FLAG_OPEN_DRAIN);
+ assign_bit(FLAG_OPEN_SOURCE, &flags,
+ lflags & GPIO_V2_LINE_FLAG_OPEN_SOURCE);

- assign_bit(FLAG_EVENT_CLOCK_REALTIME, flagsp,
- flags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME);
- assign_bit(FLAG_EVENT_CLOCK_HTE, flagsp,
- flags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE);
+ assign_bit(FLAG_PULL_UP, &flags,
+ lflags & GPIO_V2_LINE_FLAG_BIAS_PULL_UP);
+ assign_bit(FLAG_PULL_DOWN, &flags,
+ lflags & GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN);
+ assign_bit(FLAG_BIAS_DISABLE, &flags,
+ lflags & GPIO_V2_LINE_FLAG_BIAS_DISABLED);
+
+ assign_bit(FLAG_EVENT_CLOCK_REALTIME, &flags,
+ lflags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME);
+ assign_bit(FLAG_EVENT_CLOCK_HTE, &flags,
+ lflags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE);
+
+ WRITE_ONCE(*flagsp, flags);
}

static long linereq_get_values(struct linereq *lr, void __user *ip)

--
2.43.0