Re: [PATCH v2 net-next 2/3] net: dsa: lan9303: define LAN9303_NUM_PORTS 3

From: Egil Hjelmeland
Date: Tue Aug 01 2017 - 09:46:25 EST

On 01. aug. 2017 15:27, Andrew Lunn wrote:
On Tue, Aug 01, 2017 at 02:31:44PM +0200, Egil Hjelmeland wrote:
On 01. aug. 2017 13:49, Juergen Borleis wrote:
Hi Egil,

On Tuesday 01 August 2017 13:14:38 Egil Hjelmeland wrote:
Will be used instead of '3' in upcomming patches.

+#define LAN9303_NUM_PORTS 3

Maybe we should put this macro into a shared location because
in "net/dsa/tag_lan9303.c" there is already a "#define LAN9303_MAX_PORTS


Is there any suitable shared location for such driver specific
I could change the name to LAN9303_MAX_PORTS so it the same.
Rhymes better with DSA_MAX_PORTS too.

Hi Egil, Juergen

The other tag drivers do:

if (source_port >= ds->num_ports || !ds->ports[source_port].netdev)
return NULL;

or just

if (!ds->ports[port].netdev)
return NULL;

The first version is the safest, since a malicious switch could return
port 42, and you are accessing way off the end of ds->ports[]. It does
however require you call dsa_switch_alloc() with the correct number of

Sounds like a plan for a later patch, when changing to dsa_switch_alloc(LAN9303_NUM_PORTS)