svn commit: r315136 - head/sys/netpfil/pf

[Kristof Provost]

On 15 Mar 2017, at 15:45, John Baldwin wrote:
> You are ignoring interrupts and preemption.  Suppose you get an 
> interrupt
> after 'wakeup_one(pf_purge_thread)' and before 'tsleep(..., 0)' in
> pf_unload().  If the interrupt preempts and results in the purge 
> thread
> running and issuing its wakeup before the thread executing pf_unload()
> resumes, then eventually when pf_unload() resumes it will do a 
> tsleep() with
> no timeout that will never be awoken.
>
Thank you for the thorough explanation. I’ll work on a fix and post it 
for
review as soon as I can.

> You obviously didn't test this in a debug kernel since there is a 
> KASSERT
> explicitly to catch obvious tsleep races in _sleep():
>
>         KASSERT(sbt != 0 || mtx_owned(&Giant) || lock != NULL,
>             ("sleeping without a lock"));
>
I’m sure I did test this with both INVARIANTS and WITNESS enabled.
Is Giant held during module load/unload?

Regards,
Kristof