net: dsa: document the existing switch tree notifiers and add a new one

The existence of dsa_broadcast has generated some confusion in the past:
https://www.mail-archive.com/netdev@vger.kernel.org/msg365042.html

So let's document the existing dsa_port_notify and dsa_broadcast
functions and explain when each of them should be used.

Also, in fact, the in-between function has always been there but was
lacking a name, and is the main reason for this patch: dsa_tree_notify.
Refactor dsa_broadcast to use it.

This patch also moves dsa_broadcast (a top-level function) to dsa2.c,
where it really belonged in the first place, but had no companion so it
stood with dsa_port_notify.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index cc13549..2953d0c 100644 (file)
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -22,6 +22,49 @@ static DEFINE_MUTEX(dsa2_mutex);
 LIST_HEAD(dsa_tree_list);
 
 /**
+ * dsa_tree_notify - Execute code for all switches in a DSA switch tree.
+ * @dst: collection of struct dsa_switch devices to notify.
+ * @e: event, must be of type DSA_NOTIFIER_*
+ * @v: event-specific value.
+ *
+ * Given a struct dsa_switch_tree, this can be used to run a function once for
+ * each member DSA switch. The other alternative of traversing the tree is only
+ * through its ports list, which does not uniquely list the switches.
+ */
+int dsa_tree_notify(struct dsa_switch_tree *dst, unsigned long e, void *v)
+{
+       struct raw_notifier_head *nh = &dst->nh;
+       int err;
+
+       err = raw_notifier_call_chain(nh, e, v);
+
+       return notifier_to_errno(err);
+}
+
+/**
+ * dsa_broadcast - Notify all DSA trees in the system.
+ * @e: event, must be of type DSA_NOTIFIER_*
+ * @v: event-specific value.
+ *
+ * Can be used to notify the switching fabric of events such as cross-chip
+ * bridging between disjoint trees (such as islands of tagger-compatible
+ * switches bridged by an incompatible middle switch).
+ */
+int dsa_broadcast(unsigned long e, void *v)
+{
+       struct dsa_switch_tree *dst;
+       int err = 0;
+
+       list_for_each_entry(dst, &dsa_tree_list, list) {
+               err = dsa_tree_notify(dst, e, v);
+               if (err)
+                       break;
+       }
+
+       return err;
+}
+
+/**
  * dsa_lag_map() - Map LAG netdev to a linear LAG ID
  * @dst: Tree in which to record the mapping.
  * @lag: Netdev that is to be mapped to an ID.

diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index 2ce46bb..3cc1e6d 100644 (file)
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -283,6 +283,8 @@ void dsa_switch_unregister_notifier(struct dsa_switch *ds);
 /* dsa2.c */
 void dsa_lag_map(struct dsa_switch_tree *dst, struct net_device *lag);
 void dsa_lag_unmap(struct dsa_switch_tree *dst, struct net_device *lag);
+int dsa_tree_notify(struct dsa_switch_tree *dst, unsigned long e, void *v);
+int dsa_broadcast(unsigned long e, void *v);
 
 extern struct list_head dsa_tree_list;
 

diff --git a/net/dsa/port.c b/net/dsa/port.c
index f5b0f72..a8886cf 100644 (file)
--- a/net/dsa/port.c
+++ b/net/dsa/port.c
@@ -13,31 +13,21 @@
 
 #include "dsa_priv.h"
 
-static int dsa_broadcast(unsigned long e, void *v)
-{
-       struct dsa_switch_tree *dst;
-       int err = 0;
-
-       list_for_each_entry(dst, &dsa_tree_list, list) {
-               struct raw_notifier_head *nh = &dst->nh;
-
-               err = raw_notifier_call_chain(nh, e, v);
-               err = notifier_to_errno(err);
-               if (err)
-                       break;
-       }
-
-       return err;
-}
-
+/**
+ * dsa_port_notify - Notify the switching fabric of changes to a port
+ * @dp: port on which change occurred
+ * @e: event, must be of type DSA_NOTIFIER_*
+ * @v: event-specific value.
+ *
+ * Notify all switches in the DSA tree that this port's switch belongs to,
+ * including this switch itself, of an event. Allows the other switches to
+ * reconfigure themselves for cross-chip operations. Can also be used to
+ * reconfigure ports without net_devices (CPU ports, DSA links) whenever
+ * a user port's state changes.
+ */
 static int dsa_port_notify(const struct dsa_port *dp, unsigned long e, void *v)
 {
-       struct raw_notifier_head *nh = &dp->ds->dst->nh;
-       int err;
-
-       err = raw_notifier_call_chain(nh, e, v);
-
-       return notifier_to_errno(err);
+       return dsa_tree_notify(dp->ds->dst, e, v);
 }
 
 int dsa_port_set_state(struct dsa_port *dp, u8 state)