ieee802154/nl-mac.c: make some MLME operations optional

Check for NULL before calling the following operations from "struct
ieee802154_mlme_ops": assoc_req, assoc_resp, disassoc_req, start_req,
and scan_req.

This fixes a current oops where those functions are called but not
implemented. It also updates the documentation to clarify that they
are now optional by design. If a call to an unimplemented function
is attempted, the kernel returns EOPNOTSUPP via netlink.

The following operations are still required: get_phy, get_pan_id,
get_short_addr, and get_dsn.

Note that the places where this patch changes the initialization
of "ret" should not affect the rest of the code since "ret" was
always set (again) before returning its value.

Signed-off-by: Werner Almesberger <werner@almesberger.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/net/ieee802154_netdev.h b/include/net/ieee802154_netdev.h
index 642f94c0fa2f..8196d5d40359 100644
--- a/include/net/ieee802154_netdev.h
+++ b/include/net/ieee802154_netdev.h
@@ -85,6 +85,8 @@ struct wpan_phy;
  * Use wpan_wpy_put to put that reference.
  */
 struct ieee802154_mlme_ops {
+        /* The following fields are optional (can be NULL). */
+
         int (*assoc_req)(struct net_device *dev,
                         struct ieee802154_addr *addr,
                         u8 channel, u8 page, u8 cap);
@@ -101,6 +103,8 @@ struct ieee802154_mlme_ops {
         int (*scan_req)(struct net_device *dev,
                         u8 type, u32 channels, u8 page, u8 duration);
 
+        /* The fields below are required. */
+
         struct wpan_phy *(*get_phy)(const struct net_device *dev);
 
         /*