Jason R Thorpe wrote:
> You should always use them.  Consider an MP system.

I'm aware of that.

However, that code does:

fp = fd_getfile(..)
if (fp->f_type == ...) {
	cmd = XX;
	break; /* fp pointer no longer used */
}
vp = (struct vnode *)fp->f_data;
/* fp pointer no longer used */

There already IS possible race condition between fd_getfile() and
later checks, even FILE_USE(). Note also that i.e. sys_read(),
sys_write(), sys_pread(), sys_pwrite() also check fp->f_flag (and
eventually bail out) before FILE_USE().

Jaromir
-- 
Jaromir Dolecek <jdolecek@NetBSD.org> http://www.NetBSD.org/Ports/i386/ps2.html
-=- We should be mindful of the potential goal, but as the tantric    -=-
-=- Buddhist masters say, ``You may notice during meditation that you -=-
-=- sometimes levitate or glow.   Do not let this distract you.''     -=-