Now that we use a klist when looking up regulator devices, we can avoid
locking regulator_list_mutex if we take a reference on the regulator
device, if one is found.
This change would be useful if for example regulator devices could be
registered on demand when a driver requests them. regulator_register()
could end up being called from within _regulator_get while the lock on
regulator_list_mutex is being held, causing a deadlock.
This sequence illustrates the situation described above:
tegra_hdmi_probe
_regulator_get
regulator_dev_lookup
of_device_probe
reg_fixed_voltage_probe
regulator_register
Signed-off-by: Tomeu Vizoso <[email protected]>
---
Changes in v5:
- Use regulator_class' klist of devices instead of regulator_list to
store and lookup regulator devices.
Changes in v4:
- Take a reference to the regulator's device to prevent dangling
pointers
Changes in v3:
- Avoid unlocking the regulator device's mutex if we don't have a device
Changes in v2:
- Acquire regulator device lock before returning from
regulator_dev_lookup()
drivers/regulator/core.c | 49 +++++++++++++++++++++++++++++-------------------
1 file changed, 30 insertions(+), 19 deletions(-)
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index b048af9c1ae4..24245c78b58c 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1328,7 +1328,7 @@ static void regulator_supply_alias(struct device **dev,
const char **supply)
static int of_node_match(struct device *dev, const void *data)
{
- return dev->of_node == data;
+ return dev->of_node == data && get_device(dev);
}
static struct regulator_dev *of_find_regulator_by_node(struct device_node *np)
@@ -1344,7 +1344,7 @@ static int regulator_match(struct device *dev, const void
*data)
{
struct regulator_dev *r = dev_to_rdev(dev);
- return strcmp(rdev_get_name(r), data) == 0;
+ return strcmp(rdev_get_name(r), data) == 0 && get_device(dev);
}
static struct regulator_dev *regulator_lookup_by_name(const char *name)
@@ -1395,16 +1395,20 @@ static struct regulator_dev
*regulator_dev_lookup(struct device *dev,
if (r)
return r;
+ mutex_lock(®ulator_list_mutex);
list_for_each_entry(map, ®ulator_map_list, list) {
/* If the mapping has a device set up it must match */
if (map->dev_name &&
(!devname || strcmp(map->dev_name, devname)))
continue;
- if (strcmp(map->supply, supply) == 0)
+ if (strcmp(map->supply, supply) == 0 &&
+ get_device(&map->regulator->dev)) {
+ mutex_unlock(®ulator_list_mutex);
return map->regulator;
+ }
}
-
+ mutex_unlock(®ulator_list_mutex);
return NULL;
}
@@ -1435,6 +1439,7 @@ static int regulator_resolve_supply(struct regulator_dev
*rdev)
if (!r) {
if (have_full_constraints()) {
r = dummy_regulator_rdev;
+ get_device(&r->dev);
} else {
dev_err(dev, "Failed to resolve %s-supply for %s\n",
rdev->supply_name, rdev->desc->name);
@@ -1444,12 +1449,16 @@ static int regulator_resolve_supply(struct
regulator_dev *rdev)
/* Recursively resolve the supply of the supply */
ret = regulator_resolve_supply(r);
- if (ret < 0)
+ if (ret < 0) {
+ put_device(&r->dev);
return ret;
+ }
ret = set_supply(rdev, r);
- if (ret < 0)
+ if (ret < 0) {
+ put_device(&r->dev);
return ret;
+ }
/* Cascade always-on state to supply */
if (_regulator_is_enabled(rdev) && rdev->supply) {
@@ -1485,8 +1494,6 @@ static struct regulator *_regulator_get(struct device
*dev, const char *id,
else
ret = -EPROBE_DEFER;
- mutex_lock(®ulator_list_mutex);
-
rdev = regulator_dev_lookup(dev, id, &ret);
if (rdev)
goto found;
@@ -1498,7 +1505,7 @@ static struct regulator *_regulator_get(struct device
*dev, const char *id,
* succeed, so, quit with appropriate error value
*/
if (ret && ret != -ENODEV)
- goto out;
+ return regulator;
if (!devname)
devname = "deviceless";
@@ -1512,40 +1519,46 @@ static struct regulator *_regulator_get(struct device
*dev, const char *id,
devname, id);
rdev = dummy_regulator_rdev;
+ get_device(&rdev->dev);
goto found;
/* Don't log an error when called from regulator_get_optional() */
} else if (!have_full_constraints() || exclusive) {
dev_warn(dev, "dummy supplies not allowed\n");
}
- mutex_unlock(®ulator_list_mutex);
return regulator;
found:
if (rdev->exclusive) {
regulator = ERR_PTR(-EPERM);
- goto out;
+ put_device(&rdev->dev);
+ return regulator;
}
if (exclusive && rdev->open_count) {
regulator = ERR_PTR(-EBUSY);
- goto out;
+ put_device(&rdev->dev);
+ return regulator;
}
ret = regulator_resolve_supply(rdev);
if (ret < 0) {
regulator = ERR_PTR(ret);
- goto out;
+ put_device(&rdev->dev);
+ return regulator;
}
- if (!try_module_get(rdev->owner))
- goto out;
+ if (!try_module_get(rdev->owner)) {
+ put_device(&rdev->dev);
+ return regulator;
+ }
regulator = create_regulator(rdev, dev, id);
if (regulator == NULL) {
regulator = ERR_PTR(-ENOMEM);
+ put_device(&rdev->dev);
module_put(rdev->owner);
- goto out;
+ return regulator;
}
rdev->open_count++;
@@ -1559,9 +1572,6 @@ found:
rdev->use_count = 0;
}
-out:
- mutex_unlock(®ulator_list_mutex);
-
return regulator;
}
@@ -1659,6 +1669,7 @@ static void _regulator_put(struct regulator *regulator)
rdev->open_count--;
rdev->exclusive = 0;
+ put_device(&rdev->dev);
mutex_unlock(&rdev->mutex);
kfree(regulator->supply_name);
--
2.4.3
--
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