Re: [PATCH net-next RFC v3] net: hdlc_x25: Queue outgoing LAPB frames

On Mon, Feb 15, 2021 at 1:25 AM Leon Romanovsky [off-list ref] wrote:

quoted

+     /* When transmitting data:
+      * first we'll remove a pseudo header of 1 byte,
+      * then the LAPB module will prepend an LAPB header of at most 3 bytes.
+      */
+     dev->needed_headroom = 3 - 1;

3 - 1 = 2

Thanks

Actually this is intentional. It makes the numbers more meaningful.

The compiler should automatically generate the "2" so there would be
no runtime penalty.