[PATCH net-next 05/10] dpll: convert dpll_lock to rwsem

@@ -19,8 +19,12 @@
 #include "dpll_core.h"
 #include "dpll_netlink.h"
 
-/* Mutex lock to protect DPLL subsystem devices and pins */
-DEFINE_MUTEX(dpll_lock);
+/* Protects the topology and lifetime of DPLL devices and pins. Taken for write
+ * to change them and for read for the whole netlink request, part of a dump or
+ * change notification that uses them. Driver callbacks are serialized by domain
+ * locks, which are only taken under this lock.
+ */
+DECLARE_RWSEM(dpll_lock);
 
 DEFINE_XARRAY_FLAGS(dpll_device_xa, XA_FLAGS_ALLOC);
 DEFINE_XARRAY_FLAGS(dpll_pin_xa, XA_FLAGS_ALLOC);

@@ -459,7 +463,7 @@ dpll_device_get(u64 clock_id, u32 device_idx, struct module *module,
 	struct dpll_device *dpll, *ret = NULL;
 	unsigned long index;
 
-	mutex_lock(&dpll_lock);
+	down_write(&dpll_lock);
 	xa_for_each(&dpll_device_xa, index, dpll) {
 		if (dpll->clock_id == clock_id &&
 		    dpll->device_idx == device_idx &&

@@ -475,7 +479,7 @@ dpll_device_get(u64 clock_id, u32 device_idx, struct module *module,
 			dpll_device_tracker_alloc(ret, tracker);
 	}
 
-	mutex_unlock(&dpll_lock);
+	up_write(&dpll_lock);
 
 	return ret;
 }

@@ -492,9 +496,9 @@ EXPORT_SYMBOL_GPL(dpll_device_get);
  */
 void dpll_device_put(struct dpll_device *dpll, dpll_tracker *tracker)
 {
-	mutex_lock(&dpll_lock);
+	down_write(&dpll_lock);
 	__dpll_device_put(dpll, tracker);
-	mutex_unlock(&dpll_lock);
+	up_write(&dpll_lock);
 }
 EXPORT_SYMBOL_GPL(dpll_device_put);
 

@@ -540,16 +544,16 @@ int dpll_device_register(struct dpll_device *dpll, enum dpll_type type,
 	if (WARN_ON(type < DPLL_TYPE_PPS || type > DPLL_TYPE_MAX))
 		return -EINVAL;
 
-	mutex_lock(&dpll_lock);
+	down_write(&dpll_lock);
 	reg = dpll_device_registration_find(dpll, ops, priv);
 	if (reg) {
-		mutex_unlock(&dpll_lock);
+		up_write(&dpll_lock);
 		return -EEXIST;
 	}
 
 	reg = kzalloc_obj(*reg);
 	if (!reg) {
-		mutex_unlock(&dpll_lock);
+		up_write(&dpll_lock);
 		return -ENOMEM;
 	}
 	reg->ops = ops;

@@ -559,13 +563,13 @@ int dpll_device_register(struct dpll_device *dpll, enum dpll_type type,
 	first_registration = list_empty(&dpll->registration_list);
 	list_add_tail(&reg->list, &dpll->registration_list);
 	if (!first_registration) {
-		mutex_unlock(&dpll_lock);
+		up_write(&dpll_lock);
 		return 0;
 	}
 
 	xa_set_mark(&dpll_device_xa, dpll->id, DPLL_REGISTERED);
 	dpll_device_create_ntf(dpll);
-	mutex_unlock(&dpll_lock);
+	up_write(&dpll_lock);
 
 	return 0;
 }

@@ -586,12 +590,12 @@ void dpll_device_unregister(struct dpll_device *dpll,
 {
 	struct dpll_device_registration *reg;
 
-	mutex_lock(&dpll_lock);
+	down_write(&dpll_lock);
 	ASSERT_DPLL_REGISTERED(dpll);
 	dpll_device_delete_ntf(dpll);
 	reg = dpll_device_registration_find(dpll, ops, priv);
 	if (WARN_ON(!reg)) {
-		mutex_unlock(&dpll_lock);
+		up_write(&dpll_lock);
 		return;
 	}
 	list_del(&reg->list);

@@ -599,11 +603,11 @@ void dpll_device_unregister(struct dpll_device *dpll,
 	kfree(reg);
 
 	if (!list_empty(&dpll->registration_list)) {
-		mutex_unlock(&dpll_lock);
+		up_write(&dpll_lock);
 		return;
 	}
 	xa_clear_mark(&dpll_device_xa, dpll->id, DPLL_REGISTERED);
-	mutex_unlock(&dpll_lock);
+	up_write(&dpll_lock);
 }
 EXPORT_SYMBOL_GPL(dpll_device_unregister);
 

@@ -771,9 +775,9 @@ int register_dpll_notifier(struct notifier_block *nb)
 {
 	int ret;
 
-	mutex_lock(&dpll_lock);
+	down_write(&dpll_lock);
 	ret = raw_notifier_chain_register(&dpll_notifier_chain, nb);
-	mutex_unlock(&dpll_lock);
+	up_write(&dpll_lock);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(register_dpll_notifier);

@@ -782,9 +786,9 @@ int unregister_dpll_notifier(struct notifier_block *nb)
 {
 	int ret;
 
-	mutex_lock(&dpll_lock);
+	down_write(&dpll_lock);
 	ret = raw_notifier_chain_unregister(&dpll_notifier_chain, nb);
-	mutex_unlock(&dpll_lock);
+	up_write(&dpll_lock);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(unregister_dpll_notifier);

@@ -812,7 +816,7 @@ dpll_pin_get(u64 clock_id, u32 pin_idx, struct module *module,
 	struct dpll_pin *pos, *ret = NULL;
 	unsigned long i;
 
-	mutex_lock(&dpll_lock);
+	down_write(&dpll_lock);
 	xa_for_each(&dpll_pin_xa, i, pos) {
 		if (pos->clock_id == clock_id &&
 		    pos->pin_idx == pin_idx &&

@@ -827,7 +831,7 @@ dpll_pin_get(u64 clock_id, u32 pin_idx, struct module *module,
 		if (!IS_ERR(ret))
 			dpll_pin_tracker_alloc(ret, tracker);
 	}
-	mutex_unlock(&dpll_lock);
+	up_write(&dpll_lock);
 
 	return ret;
 }

@@ -844,9 +848,9 @@ EXPORT_SYMBOL_GPL(dpll_pin_get);
  */
 void dpll_pin_put(struct dpll_pin *pin, dpll_tracker *tracker)
 {
-	mutex_lock(&dpll_lock);
+	down_write(&dpll_lock);
 	__dpll_pin_put(pin, tracker);
-	mutex_unlock(&dpll_lock);
+	up_write(&dpll_lock);
 }
 EXPORT_SYMBOL_GPL(dpll_pin_put);
 

@@ -859,10 +863,10 @@ EXPORT_SYMBOL_GPL(dpll_pin_put);
  */
 void dpll_pin_fwnode_set(struct dpll_pin *pin, struct fwnode_handle *fwnode)
 {
-	mutex_lock(&dpll_lock);
+	down_write(&dpll_lock);
 	fwnode_handle_put(pin->fwnode); /* Drop fwnode previously set */
 	pin->fwnode = fwnode_handle_get(fwnode);
-	mutex_unlock(&dpll_lock);
+	up_write(&dpll_lock);
 }
 EXPORT_SYMBOL_GPL(dpll_pin_fwnode_set);
 

@@ -885,7 +889,7 @@ struct dpll_pin *fwnode_dpll_pin_find(struct fwnode_handle *fwnode,
 	struct dpll_pin *pin, *ret = NULL;
 	unsigned long index;
 
-	mutex_lock(&dpll_lock);
+	down_write(&dpll_lock);
 	xa_for_each(&dpll_pin_xa, index, pin) {
 		if (pin->fwnode == fwnode) {
 			__dpll_pin_hold(pin, tracker);

@@ -893,7 +897,7 @@ struct dpll_pin *fwnode_dpll_pin_find(struct fwnode_handle *fwnode,
 			break;
 		}
 	}
-	mutex_unlock(&dpll_lock);
+	up_write(&dpll_lock);
 
 	return ret;
 }

@@ -950,7 +954,7 @@ dpll_pin_register(struct dpll_device *dpll, struct dpll_pin *pin,
 		      DPLL_PIN_CAPABILITIES_STATE_CAN_CHANGE)))
 		return -EINVAL;
 
-	mutex_lock(&dpll_lock);
+	down_write(&dpll_lock);
 
 	dev_ops = dpll_device_ops(dpll);
 	if (WARN_ON(ops->measured_freq_get &&

@@ -974,7 +978,7 @@ dpll_pin_register(struct dpll_device *dpll, struct dpll_pin *pin,
 
 	ret = __dpll_pin_register(dpll, pin, ops, priv, NULL);
 out_unlock:
-	mutex_unlock(&dpll_lock);
+	up_write(&dpll_lock);
 
 	return ret;
 }

@@ -1028,9 +1032,9 @@ void dpll_pin_unregister(struct dpll_device *dpll, struct dpll_pin *pin,
 	if (WARN_ON(!xa_empty(&pin->parent_refs)))
 		return;
 
-	mutex_lock(&dpll_lock);
+	down_write(&dpll_lock);
 	__dpll_pin_unregister(dpll, pin, ops, priv, NULL);
-	mutex_unlock(&dpll_lock);
+	up_write(&dpll_lock);
 }
 EXPORT_SYMBOL_GPL(dpll_pin_unregister);
 

@@ -1064,7 +1068,7 @@ int dpll_pin_on_pin_register(struct dpll_pin *parent, struct dpll_pin *pin,
 	    WARN_ON(!ops->direction_get))
 		return -EINVAL;
 
-	mutex_lock(&dpll_lock);
+	down_write(&dpll_lock);
 	ret = dpll_xa_ref_pin_add(&pin->parent_refs, parent, ops, priv, pin);
 	if (ret)
 		goto unlock;

@@ -1076,7 +1080,7 @@ int dpll_pin_on_pin_register(struct dpll_pin *parent, struct dpll_pin *pin,
 		}
 		dpll_pin_create_ntf(pin, parent->clock_id);
 	}
-	mutex_unlock(&dpll_lock);
+	up_write(&dpll_lock);
 
 	return ret;
 

@@ -1089,7 +1093,7 @@ int dpll_pin_on_pin_register(struct dpll_pin *parent, struct dpll_pin *pin,
 		}
 	dpll_xa_ref_pin_del(&pin->parent_refs, parent, ops, priv, pin);
 unlock:
-	mutex_unlock(&dpll_lock);
+	up_write(&dpll_lock);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(dpll_pin_on_pin_register);

@@ -1111,7 +1115,7 @@ void dpll_pin_on_pin_unregister(struct dpll_pin *parent, struct dpll_pin *pin,
 	struct dpll_pin_ref *ref;
 	unsigned long i;
 
-	mutex_lock(&dpll_lock);
+	down_write(&dpll_lock);
 	xa_for_each(&pin->dpll_refs, i, ref) {
 		reg = dpll_pin_registration_find(ref, ops, priv, parent);
 		if (!reg)

@@ -1120,7 +1124,7 @@ void dpll_pin_on_pin_unregister(struct dpll_pin *parent, struct dpll_pin *pin,
 		__dpll_pin_unregister(ref->dpll, pin, ops, priv, parent);
 	}
 	dpll_xa_ref_pin_del(&pin->parent_refs, parent, ops, priv, pin);
-	mutex_unlock(&dpll_lock);
+	up_write(&dpll_lock);
 }
 EXPORT_SYMBOL_GPL(dpll_pin_on_pin_unregister);
 

@@ -1141,13 +1145,13 @@ int dpll_pin_ref_sync_pair_add(struct dpll_pin *pin,
 {
 	int ret;
 
-	mutex_lock(&dpll_lock);
+	down_write(&dpll_lock);
 	ret = xa_insert(&pin->ref_sync_pins, ref_sync_pin->id,
 			ref_sync_pin, GFP_KERNEL);
 	mutex_lock(&pin->domain->lock);
 	__dpll_pin_change_ntf(pin);
 	mutex_unlock(&pin->domain->lock);
-	mutex_unlock(&dpll_lock);
+	up_write(&dpll_lock);
 
 	return ret;
 }

@@ -1254,23 +1258,12 @@ const struct dpll_pin_ops *dpll_pin_ops(struct dpll_pin_ref *ref)
 
 static int __init dpll_init(void)
 {
-	int ret;
-
-	ret = genl_register_family(&dpll_nl_family);
-	if (ret)
-		goto error;
-
-	return 0;
-
-error:
-	mutex_destroy(&dpll_lock);
-	return ret;
+	return genl_register_family(&dpll_nl_family);
 }
 
 static void __exit dpll_exit(void)
 {
 	genl_unregister_family(&dpll_nl_family);
-	mutex_destroy(&dpll_lock);
 }
 
 subsys_initcall(dpll_init);

@@ -12,6 +12,7 @@
 #include <linux/mutex.h>
 #include <linux/refcount.h>
 #include <linux/ref_tracker.h>
+#include <linux/rwsem.h>
 #include "dpll_nl.h"
 
 #define DPLL_REGISTERED		XA_MARK_1

@@ -129,7 +130,7 @@ const struct dpll_pin_ops *dpll_pin_ops(struct dpll_pin_ref *ref);
 struct dpll_pin_ref *dpll_xa_ref_dpll_first(struct xarray *xa_refs);
 extern struct xarray dpll_device_xa;
 extern struct xarray dpll_pin_xa;
-extern struct mutex dpll_lock;
+extern struct rw_semaphore dpll_lock;
 
 void dpll_device_notify(struct dpll_device *dpll, unsigned long action);
 void dpll_pin_notify(struct dpll_pin *pin, u64 src_clock_id,

@@ -910,11 +910,11 @@ int dpll_device_change_ntf(struct dpll_device *dpll)
 {
 	int ret;
 
-	mutex_lock(&dpll_lock);
+	down_read(&dpll_lock);
 	mutex_lock(&dpll->domain->lock);
 	ret = __dpll_device_change_ntf(dpll);
 	mutex_unlock(&dpll->domain->lock);
-	mutex_unlock(&dpll_lock);
+	up_read(&dpll_lock);
 
 	return ret;
 }

@@ -1004,11 +1004,11 @@ int dpll_pin_change_ntf(struct dpll_pin *pin)
 {
 	int ret;
 
-	mutex_lock(&dpll_lock);
+	down_read(&dpll_lock);
 	mutex_lock(&pin->domain->lock);
 	ret = __dpll_pin_change_ntf(pin);
 	mutex_unlock(&pin->domain->lock);
-	mutex_unlock(&dpll_lock);
+	up_read(&dpll_lock);
 
 	return ret;
 }

@@ -1795,7 +1795,7 @@ int dpll_nl_pin_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 	unsigned long i;
 	int ret = 0;
 
-	mutex_lock(&dpll_lock);
+	down_read(&dpll_lock);
 	xa_for_each_marked_start(&dpll_pin_xa, i, pin, DPLL_REGISTERED,
 				 ctx->idx) {
 		if (!dpll_pin_available(pin))

@@ -1821,7 +1821,7 @@ int dpll_nl_pin_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 		}
 		genlmsg_end(skb, hdr);
 	}
-	mutex_unlock(&dpll_lock);
+	up_read(&dpll_lock);
 
 	if (ret == -EMSGSIZE) {
 		ctx->idx = i;

@@ -2019,7 +2019,7 @@ int dpll_nl_device_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 	unsigned long i;
 	int ret = 0;
 
-	mutex_lock(&dpll_lock);
+	down_read(&dpll_lock);
 	xa_for_each_marked_start(&dpll_device_xa, i, dpll, DPLL_REGISTERED,
 				 ctx->idx) {
 		hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid,

@@ -2038,7 +2038,7 @@ int dpll_nl_device_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 		}
 		genlmsg_end(skb, hdr);
 	}
-	mutex_unlock(&dpll_lock);
+	up_read(&dpll_lock);
 
 	if (ret == -EMSGSIZE) {
 		ctx->idx = i;

@@ -2056,7 +2056,7 @@ int dpll_pre_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
 	if (GENL_REQ_ATTR_CHECK(info, DPLL_A_ID))
 		return -EINVAL;
 
-	mutex_lock(&dpll_lock);
+	down_read(&dpll_lock);
 	id = nla_get_u32(info->attrs[DPLL_A_ID]);
 	dpll = dpll_device_get_by_id(id);
 	if (!dpll) {

@@ -2067,7 +2067,7 @@ int dpll_pre_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
 	mutex_lock(&dpll->domain->lock);
 	return 0;
 unlock:
-	mutex_unlock(&dpll_lock);
+	up_read(&dpll_lock);
 	return -ENODEV;
 }
 

@@ -2077,14 +2077,14 @@ void dpll_post_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
 	struct dpll_device *dpll = info->user_ptr[0];
 
 	mutex_unlock(&dpll->domain->lock);
-	mutex_unlock(&dpll_lock);
+	up_read(&dpll_lock);
 }
 
 int
 dpll_lock_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
 	       struct genl_info *info)
 {
-	mutex_lock(&dpll_lock);
+	down_read(&dpll_lock);
 
 	return 0;
 }

@@ -2093,7 +2093,7 @@ void
 dpll_unlock_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
 		 struct genl_info *info)
 {
-	mutex_unlock(&dpll_lock);
+	up_read(&dpll_lock);
 }
 
 int dpll_pin_pre_doit(const struct genl_split_ops *ops, struct sk_buff *skb,

@@ -2102,7 +2102,7 @@ int dpll_pin_pre_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
 	struct dpll_pin *pin;
 	int ret;
 
-	mutex_lock(&dpll_lock);
+	down_read(&dpll_lock);
 	if (GENL_REQ_ATTR_CHECK(info, DPLL_A_PIN_ID)) {
 		ret = -EINVAL;
 		goto unlock_dev;

@@ -2119,7 +2119,7 @@ int dpll_pin_pre_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
 	return 0;
 
 unlock_dev:
-	mutex_unlock(&dpll_lock);
+	up_read(&dpll_lock);
 	return ret;
 }
 

@@ -2129,5 +2129,5 @@ void dpll_pin_post_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
 	struct dpll_pin *pin = info->user_ptr[0];
 
 	mutex_unlock(&pin->domain->lock);
-	mutex_unlock(&dpll_lock);
+	up_read(&dpll_lock);
 }