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gpio: mxc: fix wakeup_pads bit operations

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gpio_set_wake_irq() can be called concurrently for different pins on
the same port. The writer-vs-writer race is the concern: two concurrent
gpio_set_wake_irq() calls for different pins on the same port both do
a non-atomic read-modify-write on the same wakeup_pads word. The old
|= and &= compile to separate load/modify/store instructions that can
interleave, losing one CPU's update.

assign_bit() uses an atomic RMW instruction, so concurrent writers to
different bits in the same word are safe.

The reader side (for_each_set_bit in noirq_suspend, wakeup_pads > 0)
runs in noirq context where no concurrent writer can execute, so
reader atomicity is not needed.

wakeup_pads is a u32, while assign_bit() operates on unsigned long
pointers. On 64-bit platforms, this causes an 8-byte read-modify-write
on a 4-byte field, corrupting the adjacent is_pad_wakeup. So change
wakeup_pads to unsigned long and reorder to avoid wasting words.

And fix the enable/disable path unconditionally sets/clears the
wakeup_pads bit even when enable_irq_wake()/disable_irq_wake() fails.
Only update the bit on success.

Fixes: f60c9eac54 ("gpio: mxc: enable pad wakeup on i.MX8x platforms")
Assisted-by: LLM
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Link: https://patch.msgid.link/20261013-gpio-mxc-cleanup-v7-3-c4d769587d3e@nxp.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
This commit is contained in:
Peng Fan 2026-10-13 14:01:11 +08:00 committed by Bartosz Golaszewski
parent b7719c575d
commit 170aeff46f
1 changed files with 6 additions and 4 deletions
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10
drivers/gpio/gpio-mxc.c
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@ -72,8 +72,8 @@ struct mxc_gpio_port {
unsigned long both_edges;
struct mxc_gpio_reg_saved gpio_saved_reg;
bool power_off;
u32 wakeup_pads;
bool is_pad_wakeup;
unsigned long wakeup_pads;
u32 pad_type[32];
const struct mxc_gpio_hwdata *hwdata;
};
@ -331,16 +331,18 @@ static int gpio_set_wake_irq(struct irq_data *d, u32 enable)
ret = enable_irq_wake(port->irq_high);
else
ret = enable_irq_wake(port->irq);
port->wakeup_pads |= BIT(gpio_idx);
} else {
if (port->irq_high && (gpio_idx >= 16))
ret = disable_irq_wake(port->irq_high);
else
ret = disable_irq_wake(port->irq);
port->wakeup_pads &= ~BIT(gpio_idx);
}
if (ret)
return ret;
return ret;
assign_bit(gpio_idx, &port->wakeup_pads, enable);
return 0;
}
static int mxc_gpio_init_gc(struct mxc_gpio_port *port, int irq_base)