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Subject[PATCH 01/15 v4] regulator: core: Track dangling GPIO descriptors
Date
If a GPIO descriptor is passed to the regulator_register()
function inside the config->ena_gpiod callers must be
sure that once they call this API the regulator core
owns that descriptor and will make sure to issue
gpiod_put() on it, no matter whether the call is
successful or not.

For device tree regulators, the regulator core will
automatically set up regulator init data from the device
tree when registering a regulator by calling
regulator_of_get_init_data() which in turn calls down to
the regulator driver's .of_parse_cb() callback.
This callback (in drivers such as for max77686) may also
choose to fill in the config->ena_gpiod field with a GPIO
descriptor.

Harden the errorpath of regulator_register() to
properly gpiod_put() any passed in cfg->ena_gpiod
or any gpiod coming from the device tree on any type
of error.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
ChangeLog v3->v4:
- Resending.
ChangeLog v2->v3:
- Resending.
ChangeLog v1->v2:
- New patch, just numbering v2 to keep it in line with
the patch set it came out of.
---
drivers/regulator/core.c | 55 ++++++++++++++++++++++++++++++++--------
1 file changed, 45 insertions(+), 10 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 757619878068..79cb090ff22f 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -4868,21 +4868,33 @@ regulator_register(const struct regulator_desc *regulator_desc,
struct regulator_config *config = NULL;
static atomic_t regulator_no = ATOMIC_INIT(-1);
struct regulator_dev *rdev;
+ bool dangling_cfg_gpiod = false;
+ bool dangling_of_gpiod = false;
struct device *dev;
int ret, i;

- if (regulator_desc == NULL || cfg == NULL)
+ if (cfg == NULL)
return ERR_PTR(-EINVAL);
+ if (cfg->ena_gpiod)
+ dangling_cfg_gpiod = true;
+ if (regulator_desc == NULL) {
+ ret = -EINVAL;
+ goto rinse;
+ }

dev = cfg->dev;
WARN_ON(!dev);

- if (regulator_desc->name == NULL || regulator_desc->ops == NULL)
- return ERR_PTR(-EINVAL);
+ if (regulator_desc->name == NULL || regulator_desc->ops == NULL) {
+ ret = -EINVAL;
+ goto rinse;
+ }

if (regulator_desc->type != REGULATOR_VOLTAGE &&
- regulator_desc->type != REGULATOR_CURRENT)
- return ERR_PTR(-EINVAL);
+ regulator_desc->type != REGULATOR_CURRENT) {
+ ret = -EINVAL;
+ goto rinse;
+ }

/* Only one of each should be implemented */
WARN_ON(regulator_desc->ops->get_voltage &&
@@ -4893,16 +4905,20 @@ regulator_register(const struct regulator_desc *regulator_desc,
/* If we're using selectors we must implement list_voltage. */
if (regulator_desc->ops->get_voltage_sel &&
!regulator_desc->ops->list_voltage) {
- return ERR_PTR(-EINVAL);
+ ret = -EINVAL;
+ goto rinse;
}
if (regulator_desc->ops->set_voltage_sel &&
!regulator_desc->ops->list_voltage) {
- return ERR_PTR(-EINVAL);
+ ret = -EINVAL;
+ goto rinse;
}

rdev = kzalloc(sizeof(struct regulator_dev), GFP_KERNEL);
- if (rdev == NULL)
- return ERR_PTR(-ENOMEM);
+ if (rdev == NULL) {
+ ret = -ENOMEM;
+ goto rinse;
+ }

/*
* Duplicate the config so the driver could override it after
@@ -4911,11 +4927,22 @@ regulator_register(const struct regulator_desc *regulator_desc,
config = kmemdup(cfg, sizeof(*cfg), GFP_KERNEL);
if (config == NULL) {
kfree(rdev);
- return ERR_PTR(-ENOMEM);
+ ret = -ENOMEM;
+ goto rinse;
}

init_data = regulator_of_get_init_data(dev, regulator_desc, config,
&rdev->dev.of_node);
+ /*
+ * We need to keep track of any GPIO descriptor coming from the
+ * device tree until we have handled it over to the core. If the
+ * config that was passed in to this function DOES NOT contain
+ * a descriptor, and the config after this call DOES contain
+ * a descriptor, we definately got one from parsing the device
+ * tree.
+ */
+ if (!cfg->ena_gpiod && config->ena_gpiod)
+ dangling_of_gpiod = true;
if (!init_data) {
init_data = config->init_data;
rdev->dev.of_node = of_node_get(config->of_node);
@@ -4954,6 +4981,9 @@ regulator_register(const struct regulator_desc *regulator_desc,
config->ena_gpio, ret);
goto clean;
}
+ /* The regulator core took over the GPIO descriptor */
+ dangling_cfg_gpiod = false;
+ dangling_of_gpiod = false;
}

/* register with sysfs */
@@ -5039,8 +5069,13 @@ regulator_register(const struct regulator_desc *regulator_desc,
regulator_ena_gpio_free(rdev);
mutex_unlock(&regulator_list_mutex);
clean:
+ if (dangling_of_gpiod)
+ gpiod_put(config->ena_gpiod);
kfree(rdev);
kfree(config);
+rinse:
+ if (dangling_cfg_gpiod)
+ gpiod_put(cfg->ena_gpiod);
return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(regulator_register);
--
2.19.2
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