From a23eadfae2fd45536a355b785d5a1533e1955c22 Mon Sep 17 00:00:00 2001 From: Tommaso Cucinotta Date: Tue, 19 Jul 2016 11:44:50 +0200 Subject: [PATCH] sched/deadline: Fix wrap-around in DL heap Current code in cpudeadline.c has a bug in re-heapifying when adding a new element at the end of the heap, because a deadline value of 0 is temporarily set in the new elem, then cpudl_change_key() is called with the actual elem deadline as param. However, the function compares the new deadline to set with the one previously in the elem, which is 0. So, if current absolute deadlines grew so much to have negative values as s64, the comparison in cpudl_change_key() makes the wrong decision. Instead, as from dl_time_before(), the kernel should handle correctly abs deadlines wrap-arounds. This patch fixes the problem with a minimally invasive change that forces cpudl_change_key() to heapify up in this case. Signed-off-by: Tommaso Cucinotta Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Luca Abeni Cc: Juri Lelli Cc: Juri Lelli Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1468921493-10054-2-git-send-email-tommaso.cucinotta@sssup.it Signed-off-by: Ingo Molnar --- kernel/sched/cpudeadline.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c index 5be58820465cc..d4184498c9f5e 100644 --- a/kernel/sched/cpudeadline.c +++ b/kernel/sched/cpudeadline.c @@ -168,7 +168,7 @@ void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid) if (old_idx == IDX_INVALID) { cp->size++; - cp->elements[cp->size - 1].dl = 0; + cp->elements[cp->size - 1].dl = dl; cp->elements[cp->size - 1].cpu = cpu; cp->elements[cpu].idx = cp->size - 1; cpudl_change_key(cp, cp->size - 1, dl); -- 2.39.5