Re: SoC: linuxolator update: first patch

On Tuesday 15 August 2006 11:20, Suleiman Souhlal wrote:
> John Baldwin wrote:
> > 
> >>+		KASSERT(em != NULL, ("proc_init: emuldata not found in exec case.\n"));
> >>+	}
> >>+
> >>+	em->child_clear_tid = NULL;
> >>+	em->child_set_tid = NULL;
> >>+
> >>+	/* allocate the shared struct only in clone()/fork cases
> >>+	 * in the case of clone() td = calling proc and child = pid of
> >>+	 * the newly created proc
> >>+	 */
> >>+	if (child != 0) {
> >>+   	   	if (flags & CLONE_VM) {
> >>+   		   	/* lookup the parent */
> >>+		   	p_em = em_find(td->td_proc, EMUL_LOCKED);
> >>+			KASSERT(p_em != NULL, ("proc_init: parent emuldata not found for 
> >>CLONE_VM\n"));
> >>+			em->shared = p_em->shared;
> >>+			em->shared->refs++;
> >>
> >>This is unsafe. Please use the functions in sys/refcount.h.
> > 
> > 
> > Well, in this case he's already holding a lock.  If he always holds a lock 
> > when accessing and modifying refs, then refcount_*() would only add 
overhead.
> 
> Isn't he holding the wrong lock (emul_lock vs emul_shared_lock)?

Maybe.  I think those should be merged into one lock anyway. :)

-- 
John Baldwin