net: phy: don't abuse devres in devm_mdiobus_register()

We currently have two managed helpers for mdiobus - devm_mdiobus_alloc()
and devm_mdiobus_register(). The idea behind devres is that the release
callback releases whatever resource the devm function allocates. In the
mdiobus case however there's no devres associated with the device by
devm_mdiobus_register(). Instead the release callback for
devm_mdiobus_alloc(): _devm_mdiobus_free() unregisters the device if
it is marked as managed.

This all seems wrong. The managed structure shouldn't need to know or
care about whether it's managed or not - and this is the case now for
struct mii_bus. The devres wrapper should be opaque to the managed
resource.

This changeset makes devm_mdiobus_alloc() and devm_mdiobus_register()
conform to common devres standards: devm_mdiobus_alloc() allocates a
devres structure and registers a callback that will call mdiobus_free().
__devm_mdiobus_register() allocated another devres and registers a
callback that will unregister the bus.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 77 insertions, 79 deletions

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 134f82d72da8..46b33701ad4b 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -165,79 +165,6 @@ struct mii_bus *mdiobus_alloc_size(size_t size)
 }
 EXPORT_SYMBOL(mdiobus_alloc_size);
 
-static void _devm_mdiobus_free(struct device *dev, void *res)
-{
-	struct mii_bus *bus = *(struct mii_bus **)res;
-
-	if (bus->is_managed_registered && bus->state == MDIOBUS_REGISTERED)
-		mdiobus_unregister(bus);
-
-	mdiobus_free(bus);
-}
-
-static int devm_mdiobus_match(struct device *dev, void *res, void *data)
-{
-	struct mii_bus **r = res;
-
-	if (WARN_ON(!r || !*r))
-		return 0;
-
-	return *r == data;
-}
-
-/**
- * devm_mdiobus_alloc_size - Resource-managed mdiobus_alloc_size()
- * @dev:		Device to allocate mii_bus for
- * @sizeof_priv:	Space to allocate for private structure.
- *
- * Managed mdiobus_alloc_size. mii_bus allocated with this function is
- * automatically freed on driver detach.
- *
- * If an mii_bus allocated with this function needs to be freed separately,
- * devm_mdiobus_free() must be used.
- *
- * RETURNS:
- * Pointer to allocated mii_bus on success, NULL on failure.
- */
-struct mii_bus *devm_mdiobus_alloc_size(struct device *dev, int sizeof_priv)
-{
-	struct mii_bus **ptr, *bus;
-
-	ptr = devres_alloc(_devm_mdiobus_free, sizeof(*ptr), GFP_KERNEL);
-	if (!ptr)
-		return NULL;
-
-	/* use raw alloc_dr for kmalloc caller tracing */
-	bus = mdiobus_alloc_size(sizeof_priv);
-	if (bus) {
-		*ptr = bus;
-		devres_add(dev, ptr);
-		bus->is_managed = 1;
-	} else {
-		devres_free(ptr);
-	}
-
-	return bus;
-}
-EXPORT_SYMBOL_GPL(devm_mdiobus_alloc_size);
-
-/**
- * devm_mdiobus_free - Resource-managed mdiobus_free()
- * @dev:		Device this mii_bus belongs to
- * @bus:		the mii_bus associated with the device
- *
- * Free mii_bus allocated with devm_mdiobus_alloc_size().
- */
-void devm_mdiobus_free(struct device *dev, struct mii_bus *bus)
-{
-	int rc;
-
-	rc = devres_release(dev, _devm_mdiobus_free,
-			    devm_mdiobus_match, bus);
-	WARN_ON(rc);
-}
-EXPORT_SYMBOL_GPL(devm_mdiobus_free);
-
 /**
  * mdiobus_release - mii_bus device release callback
  * @d: the target struct device that contains the mii_bus
diff --git a/drivers/net/phy/mdio_devres.c b/drivers/net/phy/mdio_devres.c
index 3ee887733d4a..0b9bd9a61378 100644
--- a/drivers/net/phy/mdio_devres.c
+++ b/drivers/net/phy/mdio_devres.c
@@ -1,25 +1,96 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#include <linux/device.h>
 #include <linux/phy.h>
+#include <linux/stddef.h>
+
+struct mdiobus_devres {
+	struct mii_bus *mii;
+};
+
+static void devm_mdiobus_free(struct device *dev, void *this)
+{
+	struct mdiobus_devres *dr = this;
+
+	mdiobus_free(dr->mii);
+}
+
+/**
+ * devm_mdiobus_alloc_size - Resource-managed mdiobus_alloc_size()
+ * @dev:		Device to allocate mii_bus for
+ * @sizeof_priv:	Space to allocate for private structure
+ *
+ * Managed mdiobus_alloc_size. mii_bus allocated with this function is
+ * automatically freed on driver detach.
+ *
+ * RETURNS:
+ * Pointer to allocated mii_bus on success, NULL on out-of-memory error.
+ */
+struct mii_bus *devm_mdiobus_alloc_size(struct device *dev, int sizeof_priv)
+{
+	struct mdiobus_devres *dr;
+
+	dr = devres_alloc(devm_mdiobus_free, sizeof(*dr), GFP_KERNEL);
+	if (!dr)
+		return NULL;
+
+	dr->mii = mdiobus_alloc_size(sizeof_priv);
+	if (!dr->mii) {
+		devres_free(dr);
+		return NULL;
+	}
+
+	devres_add(dev, dr);
+	return dr->mii;
+}
+EXPORT_SYMBOL(devm_mdiobus_alloc_size);
+
+static void devm_mdiobus_unregister(struct device *dev, void *this)
+{
+	struct mdiobus_devres *dr = this;
+
+	mdiobus_unregister(dr->mii);
+}
+
+static int mdiobus_devres_match(struct device *dev,
+				void *this, void *match_data)
+{
+	struct mdiobus_devres *res = this;
+	struct mii_bus *mii = match_data;
+
+	return mii == res->mii;
+}
 
 /**
  * __devm_mdiobus_register - Resource-managed variant of mdiobus_register()
+ * @dev:	Device to register mii_bus for
  * @bus:	MII bus structure to register
  * @owner:	Owning module
  *
  * Returns 0 on success, negative error number on failure.
  */
-int __devm_mdiobus_register(struct mii_bus *bus, struct module *owner)
+int __devm_mdiobus_register(struct device *dev, struct mii_bus *bus,
+			    struct module *owner)
 {
+	struct mdiobus_devres *dr;
 	int ret;
 
-	if (!bus->is_managed)
-		return -EPERM;
+	if (WARN_ON(!devres_find(dev, devm_mdiobus_free,
+				 mdiobus_devres_match, bus)))
+		return -EINVAL;
+
+	dr = devres_alloc(devm_mdiobus_unregister, sizeof(*dr), GFP_KERNEL);
+	if (!dr)
+		return -ENOMEM;
 
 	ret = __mdiobus_register(bus, owner);
-	if (!ret)
-		bus->is_managed_registered = 1;
+	if (ret) {
+		devres_free(dr);
+		return ret;
+	}
 
-	return ret;
+	dr->mii = bus;
+	devres_add(dev, dr);
+	return 0;
 }
 EXPORT_SYMBOL(__devm_mdiobus_register);