Re: [PATCH RFC net-next v1] net: rework FCOE and RFS ops

[Jesse Brandeburg <jesse.brandeburg@intel.com>]

On 2/13/2024 6:13 PM, Jakub Kicinski wrote:
> On Fri,  9 Feb 2024 18:09:57 -0800 Jesse Brandeburg wrote:
>> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
>> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
>> @@ -10416,14 +10416,11 @@ static const struct net_device_ops ixgbe_netdev_ops = {
>>  	.ndo_setup_tc		= __ixgbe_setup_tc,
>>  #ifdef IXGBE_FCOE
>>  	.ndo_select_queue	= ixgbe_select_queue,
>> -	.ndo_fcoe_ddp_setup = ixgbe_fcoe_ddp_get,
>> -	.ndo_fcoe_ddp_target = ixgbe_fcoe_ddp_target,
>> -	.ndo_fcoe_ddp_done = ixgbe_fcoe_ddp_put,
>> -	.ndo_fcoe_enable = ixgbe_fcoe_enable,
>> -	.ndo_fcoe_disable = ixgbe_fcoe_disable,
>> -	.ndo_fcoe_get_wwn = ixgbe_fcoe_get_wwn,
>> -	.ndo_fcoe_get_hbainfo = ixgbe_fcoe_get_hbainfo,
>>  #endif /* IXGBE_FCOE */
>> +	SET_FCOE_OPS(ixgbe_fcoe_enable, ixgbe_fcoe_disable,
>> +		     ixgbe_fcoe_ddp_target, ixgbe_fcoe_ddp_get,
>> +		     ixgbe_fcoe_ddp_put, ixgbe_fcoe_get_hbainfo)
>> +	SET_FCOE_GET_WWN_OPS(ixgbe_fcoe_get_wwn)
>>  	.ndo_set_features = ixgbe_set_features,
>>  	.ndo_fix_features = ixgbe_fix_features,
>>  	.ndo_fdb_add		= ixgbe_ndo_fdb_add,
> 
> If we'd be having a vote - I personally find the #ifdef far more
> readable.

I hear you there, BUT, the gain in "no mistakes" in CONFIG_FOO={y|n|m}
compatibility is non-trivial in my mind, *and* it removes all the ifdefs
around functions and a bunch of code from the drivers with
__maybe_unused etc.

Would it be less ugly if I used something else like a macro per
function/line?

Also, I was trying to migrate this ops subsystem "to start" and then do
others, so there is a larger discussion here. The PM infra already has
this kind of mechanism (see SET_SYSTEM_SLEEP_PM_OPS(),
SIMPLE_DEV_PM_OPS(), etc.

It also allows the compiler to discard the unused functions at link time.