net: Explicitly dereference the function pointer

[zlei]

Summary

This is most useful to make it easier to search the calling of ifnet routines by regular expression.

No functional change intended.

MFC after: 2 weeks

[glebius]

I personally don't like the change. Readability is reduced. I also don't understand the motivation. If you use grep for ->if_transmit\( you will find all calls of the method and nothing extra.

[zlei]

In D52346#1195167, @glebius wrote:

I personally don't like the change. Readability is reduced. I also don't understand the motivation. If you use grep for ->if_transmit\( you will find all calls of the method and nothing extra.

I'd admit this reduce readability somewhat. The motivation to keep the style of all calls of function pointers consistent.

Yes I have ever grep as you suggested, but eventually I figured out that I missed some, for example

# grep -Er 'if_transmit)\(' sys
sys/net/if_vlan.c:	error = (p->if_transmit)(p, m);
sys/net/if_fwsubr.c:		error = (ifp->if_transmit)(ifp, m);
sys/net/if_fwsubr.c:			error = (ifp->if_transmit)(ifp, m);
sys/net/if.c:	return ((*ifp->if_transmit)(ifp, m));
sys/net/if_tuntap.c:	error = (ifp->if_transmit)(ifp, m0);
sys/net/if_ethersubr.c:	return ((ifp->if_transmit)(ifp, m));
sys/net/if_lagg.c:	return (ifp->if_transmit)(ifp, m);
sys/netgraph/ng_iface.c:		error = (ifp->if_transmit)(ifp, m);
sys/dev/netmap/netmap_kern.h:	int     (*if_transmit)(if_t, struct mbuf *);

We also have IfAPI if_transmit(), so by intuition I'd like to distinguish calls to functions and that to function pointers.