For some reason gpiochip_export() would invalidate all the descriptors
of a chip if exporting it to sysfs failed. This does not appear as
necessary. Remove that part of the code.
While we are at it, add a note about the non-safety of temporarily
releasing a spinlock in the middle of the loop that protects its
iterator, and explain why this is done.
Signed-off-by: Alexandre Courbot <acour...@nvidia.com>
---
drivers/gpio/gpiolib-sysfs.c | 20 +++++++++-----------
1 file changed, 9 insertions(+), 11 deletions(-)
diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 3516502059f2..f150aa288fa1 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -760,18 +760,8 @@ int gpiochip_export(struct gpio_chip *chip)
chip->exported = (status == 0);
mutex_unlock(&sysfs_lock);
- if (status) {
- unsigned long flags;
- unsigned gpio;
-
- spin_lock_irqsave(&gpio_lock, flags);
- gpio = 0;
- while (gpio < chip->ngpio)
- chip->desc[gpio++].chip = NULL;
- spin_unlock_irqrestore(&gpio_lock, flags);
-
+ if (status)
chip_dbg(chip, "%s: status %d\n", __func__, status);
- }
return status;
}
@@ -817,6 +807,14 @@ static int __init gpiolib_sysfs_init(void)
if (!chip || chip->exported)
continue;
+ /*
+ * TODO we yield gpio_lock here because gpiochip_export()
+ * acquires a mutex. This is unsafe and needs to be fixed.
+ *
+ * Also it would be nice to use gpiochip_find() here so we
+ * can keep gpio_chips local to gpiolib.c, but the yield of
+ * gpio_lock prevents us from doing this.
+ */
spin_unlock_irqrestore(&gpio_lock, flags);
status = gpiochip_export(chip);
spin_lock_irqsave(&gpio_lock, flags);
--
2.0.1
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