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>

1 files changed, 13 insertions, 23 deletions

diff --git a/net/dsa/port.c b/net/dsa/port.c
index f5b0f72ee7cd..a8886cf40160 100644
--- 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)