Hi, On 19/07/16 11:44, Tommaso Cucinotta wrote: > 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. > > Cc: Peter Zijlstra <[email protected]> > Cc: Juri Lelli <[email protected]> > Cc: Luca Abeni <[email protected]> > Reviewed-by: Luca Abeni <[email protected]> > Signed-off-by: Tommaso Cucinotta <[email protected]> > --- > 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 5be5882..d418449 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);
Looks good. I'd only change the subject to something like: sched/deadline: Wrap-around bugfix for cpu heap Best, - Juri
