Unserializing ioctl() system calls

["Spinka, Kristofer" <kspinka@style.net>]

I noticed that even in the 2.6.6 code, callers to ioctl 
system call (sys_ioctl in fs/ioctl.c) are serialized with 
{lock,unlock}_kernel().

I realize that many kernel modules, and POSIX for that 
matter, may not be ready to make this more concurrent.

I propose adding a flag to indicate that the underlying 
module would like to support its own concurrency 
management, and thus we avoid grabbing the BKL around the 
f_op->ioctl call.

The default behavior would adhere to existing standards, 
and if the flag is present (in the underlying module), we 
let the module (or modules) handle it.

Reasonable?

   /kristofer