diff options
| author | Alexandre Courbot <acourbot@nvidia.com> | 2014-07-22 16:17:40 +0900 |
|---|---|---|
| committer | Linus Walleij <linus.walleij@linaro.org> | 2014-07-23 17:37:51 +0200 |
| commit | 14141a9352d007434ff61df1e16a2bcaf3119307 (patch) | |
| tree | f54c02c3344952004a08f1ea3f1913467c5fa357 /drivers/gpio | |
| parent | f63ad7ed71e525b74fe486d25cdc788d6531f4a9 (diff) | |
| download | linux-14141a9352d007434ff61df1e16a2bcaf3119307.tar.bz2 | |
gpio: simplify gpiochip_export()
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 <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'drivers/gpio')
| -rw-r--r-- | drivers/gpio/gpiolib-sysfs.c | 20 |
1 files 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); |