[PATCH 4.20 020/171] xtensa: SMP: fix ccount_timer_shutdown

Greg Kroah-Hartman
2019-03-12T17:12:16Z

[ Upstream commit 4fe8713b873fc881284722ce4ac47995de7cf62c ]

ccount_timer_shutdown is called from the atomic context in the
secondary_start_kernel, resulting in the following BUG:

BUG: sleeping function called from invalid context
in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/1
Preemption disabled at:
secondary_start_kernel+0xa1/0x130
Call Trace:
___might_sleep+0xe7/0xfc
__might_sleep+0x41/0x44
synchronize_irq+0x24/0x64
disable_irq+0x11/0x14
ccount_timer_shutdown+0x12/0x20
clockevents_switch_state+0x82/0xb4
clockevents_exchange_device+0x54/0x60
tick_check_new_device+0x46/0x70
clockevents_register_device+0x8c/0xc8
clockevents_config_and_register+0x1d/0x2c
local_timer_setup+0x75/0x7c
secondary_start_kernel+0xb4/0x130
should_never_return+0x32/0x35

Use disable_irq_nosync instead of disable_irq to avoid it.
This is safe because the ccount timer IRQ is per-CPU, and once IRQ is
masked the ISR will not be called.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/xtensa/kernel/time.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/xtensa/kernel/time.c b/arch/xtensa/kernel/time.c
index fd524a54d2ab..378186b5eb40 100644
--- a/arch/xtensa/kernel/time.c
+++ b/arch/xtensa/kernel/time.c
@@ -89,7 +89,7 @@ static int ccount_timer_shutdown(struct clock_event_device *evt)
container_of(evt, struct ccount_timer, evt);

if (timer->irq_enabled) {
- disable_irq(evt->irq);
+ disable_irq_nosync(evt->irq);
timer->irq_enabled = 0;
}
return 0;
--
2.19.1