Re: [PATCH net-next 07/11] net: fec: use switch statement to check the type of tx_buf

[David Laight]

On Tue, 13 Jan 2026 11:29:35 +0800
Wei Fang <wei.fang@xxxxxxx> wrote:

> The tx_buf has three types: FEC_TXBUF_T_SKB, FEC_TXBUF_T_XDP_NDO and
> FEC_TXBUF_T_XDP_TX. Currently, the driver uses 'if...else...' statements
> to check the type and perform the corresponding processing. This is very
> detrimental to future expansion. For example, if new types are added to
> support XDP zero copy in the future, continuing to use 'if...else...'
> would be a very bad coding style. So the 'if...else...' statements in
> the current driver are replaced with switch statements to support XDP
> zero copy in the future.

The if...else... sequence has the advantage that the common 'cases'
can be put first.
The compiler will use a branch tree for a switch statement (jumps tables
are pretty much not allowed because of speculative execution issues) and
limit the maximum number of branches.
That is likely to be pessimal in many cases - especially if it generates
mispredicted branches for the common cases.

So not clear cut at all.

	David