linux-kernel - [PATCH net-next v2 1/6] net: dsa: comment hot path requirements

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Date:   Tue, 30 May 2017 14:33:14 -0400
From:   Vivien Didelot <vivien.didelot@...oirfairelinux.com>
To:     netdev@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, kernel@...oirfairelinux.com,
        "David S. Miller" <davem@...emloft.net>,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...oirfairelinux.com>
Subject: [PATCH net-next v2 1/6] net: dsa: comment hot path requirements

The DSA layer uses inline helpers and copies of the tagging functions
for faster access in hot path. Add comments to detail that.

Signed-off-by: Vivien Didelot <vivien.didelot@...oirfairelinux.com>
---
 include/net/dsa.h  | 3 +++
 net/dsa/dsa_priv.h | 1 +
 2 files changed, 4 insertions(+)

diff --git a/include/net/dsa.h b/include/net/dsa.h
index c0e567c0c824..58297e4c6b31 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -126,6 +126,8 @@ struct dsa_switch_tree {
 	 * protocol to use.
 	 */
 	struct net_device	*master_netdev;
+
+	/* Copy of tag_ops->rcv for faster access in hot path */
 	struct sk_buff *	(*rcv)(struct sk_buff *skb,
 				       struct net_device *dev,
 				       struct packet_type *pt,
@@ -464,6 +466,7 @@ struct mii_bus *dsa_host_dev_to_mii_bus(struct device *dev);
 
 struct net_device *dsa_dev_to_net_device(struct device *dev);
 
+/* Keep inline for faster access in hot path */
 static inline bool dsa_uses_tagged_protocol(struct dsa_switch_tree *dst)
 {
 	return dst->rcv != NULL;
diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index c1d4180651af..2ce9fec9eec5 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -73,6 +73,7 @@ struct dsa_device_ops {
 };
 
 struct dsa_slave_priv {
+	/* Copy of dp->ds->dst->tag_ops->xmit for faster access in hot path */
 	struct sk_buff *	(*xmit)(struct sk_buff *skb,
 					struct net_device *dev);
 
-- 
2.13.0