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Message-Id: <20230519050702.3681791-1-chris.packham@alliedtelesis.co.nz>
Date: Fri, 19 May 2023 17:07:02 +1200
From: Chris Packham <chris.packham@...iedtelesis.co.nz>
To: linus.walleij@...aro.org, brgl@...ev.pl, andy.shevchenko@...il.com,
johan@...nel.org, maz@...nel.org, warthog618@...il.com
Cc: linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
Chris Packham <chris.packham@...iedtelesis.co.nz>
Subject: [PATCH v2] gpiolib: Avoid side effects in gpio_is_visible()
On a system with pca9555 GPIOs that have been exported via sysfs the
following warning could be triggered on kexec().
WARNING: CPU: 0 PID: 265 at drivers/gpio/gpiolib.c:3411 gpiochip_disable_irq
Call trace:
gpiochip_disable_irq
machine_crash_shutdown
__crash_kexec
panic
sysrq_reset_seq_param_set
__handle_sysrq
write_sysrq_trigger
The warning is triggered because there is an irq_desc for the GPIO but
it does not have the FLAG_USED_AS_IRQ set. This is because when the GPIO
is exported via gpiod_export(), gpio_is_visible() is used to determine
if the "edge" attribute should be provided but in doing so it ends up
calling gpiochip_to_irq() which creates the irq_desc.
Remove the call to gpiod_to_irq() from gpio_is_visible(). The actual
intended creation of the irq_desc comes via edge_store() when requested
by the user.
Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
---
Notes:
Changes in v2:
- expand commit message to (hopefully) better describe the problem and
solution
- drop the inaccurate fixes tag
drivers/gpio/gpiolib-sysfs.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 530dfd19d7b5..f859dcd1cbf3 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -362,8 +362,6 @@ static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
if (!show_direction)
mode = 0;
} else if (attr == &dev_attr_edge.attr) {
- if (gpiod_to_irq(desc) < 0)
- mode = 0;
if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
mode = 0;
}
--
2.40.1
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