stop ifnet ioctl (ab)use in the kernel, step 1

[David Young]

The network protocols and some drivers use ioctls to manipulate
ifnet flags, to add/delete multicast addresses, and to initialize
ifaddrs. I'd like to stop that before I tackle some problems with
ioctl synchronization. The first step is to replace calls to
ifp->if_ioctl(SIOCINITIFADDR|SIOCSIFFLAGS|SIOCADDMULTI|SIOSDELMULTI)
with calls to some new routines, if_flags_set(), if_mcast_op(), and
if_addr_init(). The new routines either call driver-provided routines
or fall back to if_ioctl. See the attached patch.

This patch isn't ready to commit, but please let me know if you have
any objections to the general approach before I continue.

Notice that I have provisionally deleted SIOCSIFDSTADDR cases from a lot
of drivers, because we can ordinarily rely on SIOCINITIFADDR to do the
same checks that SIOCSIFDSTADDR will do.

Dave

[der Mouse]

The network protocols and some drivers use ioctls to manipulate ifnet
flags, to add/delete multicast addresses, and to initialize ifaddrs.
I'd like to stop that before I tackle some [other stuff].

Why?

What is the perceived need being addressed here? Do you just find
if()_ioctl ugly compared to adding more function pointers to struct
ifnet? Is the if_ioctl() way actually causing some trouble somewhere?
Something else?

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[David Young]

Post by der Mouse

The network protocols and some drivers use ioctls to manipulate ifnet
flags, to add/delete multicast addresses, and to initialize ifaddrs.
I'd like to stop that before I tackle some [other stuff].

Why?
What is the perceived need being addressed here? Do you just find
if()_ioctl ugly compared to adding more function pointers to struct
ifnet? Is the if_ioctl() way actually causing some trouble somewhere?
Something else?

Good questions.

The if_ioctl() way leads to recursion that makes synchronizing ioctls a
worse PITA than it needs to be.

The if_ioctl() way requires lines of code that marshal arguments into an
ifreq (say) and then cast them to (void *). It's more error-prone and a
lot less type-safe than it could be.

Dave