RE: [PATCH v2 net-next 1/2] net: dsa: lan9303: Add port_fast_age and port_fdb_dump methods

From: Egil Hjelmeland

Sent: 19 October 2017 17:53

...

quoted

quoted

IMHO it is best to define a struct for the 'ctx and then do:
    ..., void *v_ctx)
{
    foo_ctx *ctx = v_ctx;
    int port = ctx->port;

That stops anyone having to double-check that the *(int *)
is operating on a pointer to an integer of the correct size.

Does casting to a struct pointer require less manual double-check than
to a int-pointer? In neither cases the compiler can protect us, IFAIK.
But on the other hand, a the text "foo_ctx" can searched in the editor.
So in that respect it can somewhat aid to the double-checking.

So I can do that.

I understand now that the caller side (lan9303_port_fast_age) is
vulnerable. Say somebody has the idea to change the "port" param
of .port_fast_age from int to u8, then my code is a trap.

Worse, change it to a long and it will work on everything except
64bit big-endian systems.

	David