netdev - [PATCH RESEND v3 net-next 1/7] net: dsa: introduce helpers for iterating through ports using dp

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Date:   Wed, 20 Oct 2021 20:49:49 +0300
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     netdev@...r.kernel.org, Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Vladimir Oltean <olteanv@...il.com>
Subject: [PATCH RESEND v3 net-next 1/7] net: dsa: introduce helpers for iterating through ports using dp

Since the DSA conversion from the ds->ports array into the dst->ports
list, the DSA API has encouraged driver writers, as well as the core
itself, to write inefficient code.

Currently, code that wants to filter by a specific type of port when
iterating, like {!unused, user, cpu, dsa}, uses the dsa_is_*_port helper.
Under the hood, this uses dsa_to_port which iterates again through
dst->ports. But the driver iterates through the port list already, so
the complexity is quadratic for the typical case of a single-switch
tree.

This patch introduces some iteration helpers where the iterator is
already a struct dsa_port *dp, so that the other variant of the
filtering functions, dsa_port_is_{unused,user,cpu_dsa}, can be used
directly on the iterator. This eliminates the second lookup.

These functions can be used both by the core and by drivers.

Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
 include/net/dsa.h | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/include/net/dsa.h b/include/net/dsa.h
index 05ebdd8d5321..440b6aca22c7 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -474,6 +474,34 @@ static inline bool dsa_is_user_port(struct dsa_switch *ds, int p)
 	return dsa_to_port(ds, p)->type == DSA_PORT_TYPE_USER;
 }
 
+#define dsa_tree_for_each_user_port(_dp, _dst) \
+	list_for_each_entry((_dp), &(_dst)->ports, list) \
+		if (dsa_port_is_user((_dp)))
+
+#define dsa_switch_for_each_port(_dp, _ds) \
+	list_for_each_entry((_dp), &(_ds)->dst->ports, list) \
+		if ((_dp)->ds == (_ds))
+
+#define dsa_switch_for_each_port_safe(_dp, _next, _ds) \
+	list_for_each_entry_safe((_dp), (_next), &(_ds)->dst->ports, list) \
+		if ((_dp)->ds == (_ds))
+
+#define dsa_switch_for_each_port_continue_reverse(_dp, _ds) \
+	list_for_each_entry_continue_reverse((_dp), &(_ds)->dst->ports, list) \
+		if ((_dp)->ds == (_ds))
+
+#define dsa_switch_for_each_available_port(_dp, _ds) \
+	dsa_switch_for_each_port((_dp), (_ds)) \
+		if (!dsa_port_is_unused((_dp)))
+
+#define dsa_switch_for_each_user_port(_dp, _ds) \
+	dsa_switch_for_each_port((_dp), (_ds)) \
+		if (dsa_port_is_user((_dp)))
+
+#define dsa_switch_for_each_cpu_port(_dp, _ds) \
+	dsa_switch_for_each_port((_dp), (_ds)) \
+		if (dsa_port_is_cpu((_dp)))
+
 static inline u32 dsa_user_ports(struct dsa_switch *ds)
 {
 	u32 mask = 0;
-- 
2.25.1