kern/94278: Crash with FIFOs and ktrace

[Robert Watson]

Synopsis: Crash with FIFOs and ktrace

Responsible-Changed-From-To: freebsd-bugs->rwatson
Responsible-Changed-By: rwatson
Responsible-Changed-When: Tue Mar 14 12:26:08 UTC 2006
Responsible-Changed-Why: 

Grab ownership, since I've also been looking at this.  David, feel free to
grab it if you'd prefer.

My reading was that actually, the fifo code is at fault for not checking
if the fdidx argument to vop_open() is -1, which implies there isn't a
file descriptor in use, and that fifos there fore can't hook up to it.
This error path may require some tweaking -- I tried having Kris add a
patch along these lines, and he reported problems that I haven't yet
investigated.

Being able to feed ktrace data to a fifo is a useful thing, but will be
difficult to re-add in the world of vnode bypass, something we might want
to add a todo item for sometime.


http://www.freebsd.org/cgi/query-pr.cgi?pr=94278