net: dsa: variable number of ports

Change the ports[DSA_MAX_PORTS] array of the dsa_switch structure for a
zero-length array, allocated at the same time as the dsa_switch
structure itself. A dsa_switch_alloc() helper is provided for that.

This commit brings no functional change yet since we pass DSA_MAX_PORTS
as the number of ports for the moment. Future patches can update the DSA
drivers separately to support dynamic number of ports.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 18 insertions, 3 deletions

diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 07e8633..de3ffb4 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -347,8 +347,8 @@ dsa_switch_setup(struct dsa_switch_tree *dst, int index,
 	/*
 	 * Allocate and initialise switch state.
 	 */
-	ds = devm_kzalloc(parent, sizeof(*ds), GFP_KERNEL);
-	if (ds == NULL)
+	ds = dsa_switch_alloc(parent, DSA_MAX_PORTS);
+	if (!ds)
 		return ERR_PTR(-ENOMEM);
 
 	ds->dst = dst;
@@ -356,7 +356,6 @@ dsa_switch_setup(struct dsa_switch_tree *dst, int index,
 	ds->cd = cd;
 	ds->ops = ops;
 	ds->priv = priv;
-	ds->dev = parent;
 
 	ret = dsa_switch_setup_one(ds, parent);
 	if (ret)
diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index 75f5d1f..4b3a44b 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -666,6 +666,22 @@ out:
 	return err;
 }
 
+struct dsa_switch *dsa_switch_alloc(struct device *dev, size_t n)
+{
+	size_t size = sizeof(struct dsa_switch) + n * sizeof(struct dsa_port);
+	struct dsa_switch *ds;
+
+	ds = devm_kzalloc(dev, size, GFP_KERNEL);
+	if (!ds)
+		return NULL;
+
+	ds->dev = dev;
+	ds->num_ports = n;
+
+	return ds;
+}
+EXPORT_SYMBOL_GPL(dsa_switch_alloc);
+
 int dsa_register_switch(struct dsa_switch *ds, struct device *dev)
 {
 	int err;