[PATCH RT 3/4] hrtimer:fix the miss of hrtimer_peek_ahead_timers in nort code

[Steven Rostedt]

3.4.97-rt121-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Zhao Hongjiang <zhaohongjiang@xxxxxxxxxx>

When we run the test "taskset -c 1 stress -m 1 --vm-bytes 50M" and
"taskset -c 1 cyclictest -t 1 -p 80 -n -m -v" with rt closed 3.4.26-rt38 kernel,
the cyclictest's result is anomalous as follow:
       0:     278:       1
       0:     279:       2
       0:     280:      17
       0:     281:    1657
       0:     282:    1680
       0:     283:    4678
       0:     284:    7026
       0:     285:    6678
       0:     286:    9677
       0:     287:   12678
       0:     288:   13090
       0:     289:   14678
       0:     290:   17677
       0:     291:   20155
       0:     292:   19678
       0:     293:   22679
       0:     294:   25676
       0:     295:   26218
       0:     296:   27679
       0:     297:   30677
       0:     298:   33283
       0:     299:   32677
       0:     300:   35676
and the result is increase continuously forever. We find that the patch
("hrtimer: fixup hrtimer callback changes for preempt-rt") has missed
hrtimer_peek_ahead_timers() in hrtimer_rt_run_pending() fuction in nort
code. We fix this and the test result isn't increase continuously as same
as the result with nort 3.4.26 kernel as follow:
       0:     636:       8
       0:     637:       7
       0:     638:       8
       0:     639:       9
       0:     640:       7
       0:     641:       9
       0:     642:       8
       0:     643:       8
       0:     644:       8
       0:     645:      32
       0:     646:    8683
       0:     647:    7760
       0:     648:    6784
       0:     649:    5797
       0:     650:    4810
       0:     651:    3823
       0:     652:    2836
       0:     653:    1849
       0:     654:     862
       0:     655:       7
       0:     656:       7
       0:     657:       7
       0:     658:       6
       0:     659:       8
       0:     660:       7

Signed-off-by: Zhao Hongjiang <zhaohongjiang@xxxxxxxxxx>
Signed-off-by: Weng Meiling <wengmeiling.weng@xxxxxxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
[PG: direct cherry pick of b236e408 from v3.6-rt]
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
 kernel/hrtimer.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 3f7d3b5b0717..afb62c7cc494 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -1457,7 +1457,11 @@ static int hrtimer_rt_defer(struct hrtimer *timer)
 
 #else
 
-static inline void hrtimer_rt_run_pending(void) { }
+static inline void hrtimer_rt_run_pending(void)
+{
+	hrtimer_peek_ahead_timers();
+}
+
 static inline int hrtimer_rt_defer(struct hrtimer *timer) { return 0; }
 
 #endif
-- 
2.0.0


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