On Wed, Oct 13, 2021 at 10:05:21AM +0000, Alvin Šipraga wrote:

Andrew also suggested this, but the discontinuity in port IDs seems to 
be an invitation for trouble. Here is an example of a series of 
functions from dsa.h:

static inline struct dsa_port *dsa_to_port(struct dsa_switch *ds, int p)
{
	struct dsa_switch_tree *dst = ds->dst;
	struct dsa_port *dp;

	list_for_each_entry(dp, &dst->ports, list)
		if (dp->ds == ds && dp->index == p)
			return dp;

	return NULL;
}

static inline bool dsa_is_user_port(struct dsa_switch *ds, int p)
{
	return dsa_to_port(ds, p)->type == DSA_PORT_TYPE_USER;
}

static inline u32 dsa_user_ports(struct dsa_switch *ds)
{
	u32 mask = 0;
	int p;

	for (p = 0; p < ds->num_ports; p++)
		if (dsa_is_user_port(ds, p))
			mask |= BIT(p);

	return mask;
}

My reading of dsa_user_ports() is that the port IDs run from 0 to 
(ds->num_ports - 1). If num_ports is 5 (4 user ports and 1 CPU port, as 
in my case), but the CPU is port 6, will we not dereference NULL when 
calling dsa_is_user_port(ds, 4)?

So set num_ports to 7.

quoted

quoted

+
+/* Chip-specific data and limits */