[PATCH] hwmon: (pmbus_core) Fix Deadlock in pmbus_regulator_get_status

[Guenter Roeck <linux@roeck-us.net>]

pmbus_regulator_get_status() acquires update_lock.
pmbus_regulator_get_error_flags() acquires it again, resulting in an
immediate deadlock.

Call _pmbus_get_flags() from pmbus_regulator_get_status() directly
to avoid the problem.

Reported-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Closes: https://lore.kernel.org/linux-hwmon/b7a3ad85-aab4-4718-a001-1d8b1c0eef36@roeck-us.net/T/#u
Cc: Naresh Solanki <Naresh.Solanki@9elements.com>
Fixes: c05f477c4ba3 ("hwmon: (pmbus/core) Implement regulator get_status")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
I want to send this in a pull request this week, and I have not heard back
from the reporters. Patrick, Naresh, please feel free to submit a similar
patch by Thursday EOB this week. Otherwise I'll send this one upstream. 

 drivers/hwmon/pmbus/pmbus_core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index 30aeb59062a5..69a4e62b6c8d 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -2946,6 +2946,7 @@ static int pmbus_regulator_get_status(struct regulator_dev *rdev)
 	struct pmbus_data *data = i2c_get_clientdata(client);
 	u8 page = rdev_get_id(rdev);
 	int status, ret;
+	int event;
 
 	mutex_lock(&data->update_lock);
 	status = pmbus_get_status(client, page, PMBUS_STATUS_WORD);
@@ -2965,7 +2966,7 @@ static int pmbus_regulator_get_status(struct regulator_dev *rdev)
 		goto unlock;
 	}
 
-	ret = pmbus_regulator_get_error_flags(rdev, &status);
+	ret = _pmbus_get_flags(data, rdev_get_id(rdev), &status, &event, false);
 	if (ret)
 		goto unlock;
 
-- 
2.39.2