dsa: Make use of the list of tag drivers

Implement the _get and _put functions to make use of the list of tag
drivers. Also, trigger the loading of the module, based on the alias
information. The _get function takes a reference on the tag driver, so
it cannot be unloaded, and the _put function releases the reference.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>

v2:
Make tag_driver_register void

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 34 insertions, 5 deletions

diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 54e89c97ce11..67d21647c500 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -125,20 +125,49 @@ const char *dsa_tag_protocol_to_str(const struct dsa_device_ops *ops)
 
 const struct dsa_device_ops *dsa_tag_driver_get(int tag_protocol)
 {
+        struct dsa_tag_driver *dsa_tag_driver;
         const struct dsa_device_ops *ops;
+        char module_name[128];
+        bool found = false;
 
-        if (tag_protocol >= DSA_TAG_LAST)
-                return ERR_PTR(-EINVAL);
-        ops = dsa_device_ops[tag_protocol];
+        snprintf(module_name, 127, "%s%d", DSA_TAG_DRIVER_ALIAS,
+                 tag_protocol);
 
-        if (!ops)
-                return ERR_PTR(-ENOPROTOOPT);
+        request_module(module_name);
+
+        mutex_lock(&dsa_tag_drivers_lock);
+        list_for_each_entry(dsa_tag_driver, &dsa_tag_drivers_list, list) {
+                ops = dsa_tag_driver->ops;
+                if (ops->proto == tag_protocol) {
+                        found = true;
+                        break;
+                }
+        }
+
+        if (found) {
+                if (!try_module_get(dsa_tag_driver->owner))
+                        ops = ERR_PTR(-ENOPROTOOPT);
+        } else {
+                ops = ERR_PTR(-ENOPROTOOPT);
+        }
+
+        mutex_unlock(&dsa_tag_drivers_lock);
 
         return ops;
 }
 
 void dsa_tag_driver_put(const struct dsa_device_ops *ops)
 {
+        struct dsa_tag_driver *dsa_tag_driver;
+
+        mutex_lock(&dsa_tag_drivers_lock);
+        list_for_each_entry(dsa_tag_driver, &dsa_tag_drivers_list, list) {
+                if (dsa_tag_driver->ops == ops) {
+                        module_put(dsa_tag_driver->owner);
+                        break;
+                }
+        }
+        mutex_unlock(&dsa_tag_drivers_lock);
 }
 
 static int dev_is_class(struct device *dev, void *class)