pwm: Unexport children before chip removal

commit 0733424c upstream.

Exported pwm channels aren't removed before the pwmchip and are
leaked. This results in invalid sysfs files. This fix removes
all exported pwm channels before chip removal.
Signed-off-by: David Hsu <davidhsu@google.com>
Fixes: 76abbdde ("pwm: Add sysfs interface")
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/pwm/core.c

@@ -293,6 +293,8 @@ int pwmchip_remove(struct pwm_chip *chip)
 	unsigned int i;
 	int ret = 0;
 
+	pwmchip_sysfs_unexport_children(chip);
+
 	mutex_lock(&pwm_lock);
 
 	for (i = 0; i < chip->npwm; i++) {

drivers/pwm/sysfs.c

@@ -340,6 +340,24 @@ void pwmchip_sysfs_unexport(struct pwm_chip *chip)
 	}
 }
 
+void pwmchip_sysfs_unexport_children(struct pwm_chip *chip)
+{
+	struct device *parent;
+	unsigned int i;
+
+	parent = class_find_device(&pwm_class, NULL, chip,
+				   pwmchip_sysfs_match);
+	if (!parent)
+		return;
+
+	for (i = 0; i < chip->npwm; i++) {
+		struct pwm_device *pwm = &chip->pwms[i];
+
+		if (test_bit(PWMF_EXPORTED, &pwm->flags))
+			pwm_unexport_child(parent, pwm);
+	}
+}
+
 static int __init pwm_sysfs_init(void)
 {
 	return class_register(&pwm_class);

include/linux/pwm.h

@@ -299,6 +299,7 @@ static inline void pwm_add_table(struct pwm_lookup *table, size_t num)
 #ifdef CONFIG_PWM_SYSFS
 void pwmchip_sysfs_export(struct pwm_chip *chip);
 void pwmchip_sysfs_unexport(struct pwm_chip *chip);
+void pwmchip_sysfs_unexport_children(struct pwm_chip *chip);
 #else
 static inline void pwmchip_sysfs_export(struct pwm_chip *chip)
 {
@@ -307,6 +308,10 @@ static inline void pwmchip_sysfs_export(struct pwm_chip *chip)
 static inline void pwmchip_sysfs_unexport(struct pwm_chip *chip)
 {
 }
+
+static inline void pwmchip_sysfs_unexport_children(struct pwm_chip *chip)
+{
+}
 #endif /* CONFIG_PWM_SYSFS */
 
 #endif /* __LINUX_PWM_H */