Re: [RFC PATCH v7 06/16] net: dsa: tag_qca: add define for handling mgmt Ethernet packet

[Florian Fainelli]

On 1/25/2022 8:01 PM, Ansuel Smith wrote:
> On Tue, Jan 25, 2022 at 07:54:15PM -0800, Florian Fainelli wrote:
> > On 1/22/2022 5:33 PM, Ansuel Smith wrote:
> > > Add all the required define to prepare support for mgmt read/write in
> > > Ethernet packet. Any packet of this type has to be dropped as the only
> > > use of these special packet is receive ack for an mgmt write request or
> > > receive data for an mgmt read request.
> > > A struct is used that emulates the Ethernet header but is used for a
> > > different purpose.
> > >
> > > Signed-off-by: Ansuel Smith <ansuelsmth@xxxxxxxxx>
> > > ---
> >
> > [snip]
> >
> > > +/* Special struct emulating a Ethernet header */
> > > +struct mgmt_ethhdr {
> > > +	u32 command;		/* command bit 31:0 */
> > > +	u32 seq;		/* seq 63:32 */
> > > +	u32 mdio_data;		/* first 4byte mdio */
> > > +	__be16 hdr;		/* qca hdr */
> > > +} __packed;
> >
> > Might be worth adding a BUILD_BUG_ON(sizeof(struct mgmt_ethhdr) !=
> > QCA_HDR_MGMT_PKG_LEN) when you start making use of that structure?
>
> Where should I put this check? Right after the struct definition,
> correct? (I just checked definition of the macro)

It would have to be in a call site where you use the structure, I have 
not checked whether putting it in a static inline function in .h file 
actually works if the inline function is not used at all.
--
Florian