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authorTommaso Cucinotta <tommaso.cucinotta@sssup.it>2016-07-19 11:44:50 +0200
committerIngo Molnar <mingo@kernel.org>2016-08-10 13:32:55 +0200
commita23eadfae2fd45536a355b785d5a1533e1955c22 (patch)
treef100911b6c15a24ba247eb94ef477bc5c323fd47 /kernel
parenta0cba2179ea4c1820fce2ee046b6ed90ecc56196 (diff)
downloadblackbird-op-linux-a23eadfae2fd45536a355b785d5a1533e1955c22.tar.gz
blackbird-op-linux-a23eadfae2fd45536a355b785d5a1533e1955c22.zip
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 <tommaso.cucinotta@sssup.it> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Luca Abeni <luca.abeni@unitn.it> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Juri Lelli <juri.lelli@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1468921493-10054-2-git-send-email-tommaso.cucinotta@sssup.it Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/cpudeadline.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c
index 5be58820465c..d4184498c9f5 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);
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