Re: fanotify as syscalls

[ebiederm@xmission.com (Eric W. Biederman)]

Linus Torvalds <torvalds@linux-foundation.org> writes:

> Quite frankly, I have _never_ever_ seen a good reason for talking to the 
> kernel with some idiotic packet interface. It's just a fancy way to do 
> ioctl's, and everybody knows that ioctl's are bad and evil. Why are fancy 
> packet interfaces suddenly much better?

For working with the networking stack there are a lot of advantages because
netlink is the interface to everything in the network stack.

There are nice things like the packet to create a new interface is the same
packet the kernel sends everyone to report a new interface etc.

netlink also seems to get the structured data thing right.  You can
parse the packet even if you don't understand everything.  Each tag is
well defined like a syscall, taking exactly one kind of argument.
Which avoids the worst failure of ioctl in that you can't even parse
everything, and the argument may be a linked list in the calling
process or something else atrocious.

All of that said syscalls are good, and I would not recommend netlink
to anything not in the network stack.

Eric