[PATCH 1/1] signal c/r: don't play with zero timeouts

["Serge E. Hallyn" <serue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>]

If it_virt_expires or it_prof_expires is zero, then don't
subtract {virt,prof}_ticks(t) from it.  This is the same
thing do_getitimer() does, and it fixes my issues with
the signals c/r patchset on s390.

Signed-off-by: Serge E. Hallyn <serue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
---
 checkpoint/signal.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/checkpoint/signal.c b/checkpoint/signal.c
index 960356c..15b7cdc 100644
--- a/checkpoint/signal.c
+++ b/checkpoint/signal.c
@@ -382,13 +382,17 @@ static int checkpoint_signal(struct ckpt_ctx *ctx, struct task_struct *t)
 	}
 	h->it_real_incr = ktime_to_ns(signal->it_real_incr);
 
-	cputime = cputime_sub(signal->it_virt_expires, virt_ticks(t));
+	cputime = signal->it_virt_expires;
+	if (!cputime_eq(cputime, cputime_zero))
+		cputime = cputime_sub(signal->it_virt_expires, virt_ticks(t));
 	cputime_to_timeval(cputime, &tval);
 	h->it_virt_value = timeval_to_ns(&tval);
 	cputime_to_timeval(signal->it_virt_incr, &tval);
 	h->it_virt_incr = timeval_to_ns(&tval);
 
-	cputime = cputime_sub(signal->it_prof_expires, prof_ticks(t));
+	cputime = signal->it_prof_expires;
+	if (!cputime_eq(cputime, cputime_zero))
+		cputime = cputime_sub(signal->it_prof_expires, prof_ticks(t));
 	cputime_to_timeval(cputime, &tval);
 	h->it_prof_value = timeval_to_ns(&tval);
 	cputime_to_timeval(signal->it_prof_incr, &tval);
-- 
1.6.1