[PATCH v3 net-next 11/14] dsa: Make use of the list of tag drivers

[Andrew Lunn]

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 <and...@lunn.ch>
Reviewed-by: Florian Fainelli <f.faine...@gmail.com>

v2:
Make tag_driver_register void
---
 net/dsa/dsa.c | 39 ++++++++++++++++++++++++++++++++++-----
 1 file 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)
-- 
2.20.1