The decrementer exception can fail to be cleared when the interrupt
returns in the case where the decrementer wraps with the next timer
still beyond decrementer_max. This results in a decrementer interrupt
storm. This is triggerable with small decrementer system with hard
and soft watchdogs disabled.
Fix this by always programming the decrementer if there was no timer.
Fixes: 0faf20a1ad16 ("powerpc/64s/interrupt: Don't enable MSR[EE] in irq
handlers unless perf is in use")
Reported-by: Alexey Kardashevskiy <a...@ozlabs.ru>
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
arch/powerpc/kernel/time.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 62361cc7281c..cd0b8b71ecdd 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -649,8 +649,9 @@ DEFINE_INTERRUPT_HANDLER_ASYNC(timer_interrupt)
__this_cpu_inc(irq_stat.timer_irqs_event);
} else {
now = *next_tb - now;
- if (now <= decrementer_max)
- set_dec_or_work(now);
+ if (now > decrementer_max)
+ now = decrementer_max;
+ set_dec_or_work(now);
__this_cpu_inc(irq_stat.timer_irqs_others);
}
--
2.23.0
