queue-4.4/xtensa-smp-fix-ccount_timer_shutdown.patch

   1 From 04ea0be0a3ed8372dbc41be1b5f119a38792801d Mon Sep 17 00:00:00 2001
   2 From: Max Filippov <jcmvbkbc@gmail.com>
   3 Date: Mon, 29 Jan 2018 09:09:41 -0800
   4 Subject: xtensa: SMP: fix ccount_timer_shutdown
   5
   6 [ Upstream commit 4fe8713b873fc881284722ce4ac47995de7cf62c ]
   7
   8 ccount_timer_shutdown is called from the atomic context in the
   9 secondary_start_kernel, resulting in the following BUG:
  10
  11 BUG: sleeping function called from invalid context
  12 in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/1
  13 Preemption disabled at:
  14   secondary_start_kernel+0xa1/0x130
  15 Call Trace:
  16   ___might_sleep+0xe7/0xfc
  17   __might_sleep+0x41/0x44
  18   synchronize_irq+0x24/0x64
  19   disable_irq+0x11/0x14
  20   ccount_timer_shutdown+0x12/0x20
  21   clockevents_switch_state+0x82/0xb4
  22   clockevents_exchange_device+0x54/0x60
  23   tick_check_new_device+0x46/0x70
  24   clockevents_register_device+0x8c/0xc8
  25   clockevents_config_and_register+0x1d/0x2c
  26   local_timer_setup+0x75/0x7c
  27   secondary_start_kernel+0xb4/0x130
  28   should_never_return+0x32/0x35
  29
  30 Use disable_irq_nosync instead of disable_irq to avoid it.
  31 This is safe because the ccount timer IRQ is per-CPU, and once IRQ is
  32 masked the ISR will not be called.
  33
  34 Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
  35 Signed-off-by: Sasha Levin <sashal@kernel.org>
  36 ---
  37  arch/xtensa/kernel/time.c | 2 +-
  38  1 file changed, 1 insertion(+), 1 deletion(-)
  39
  40 diff --git a/arch/xtensa/kernel/time.c b/arch/xtensa/kernel/time.c
  41 index b9ad9feadc2d..a992cb6a47db 100644
  42 --- a/arch/xtensa/kernel/time.c
  43 +++ b/arch/xtensa/kernel/time.c
  44 @@ -87,7 +87,7 @@ static int ccount_timer_shutdown(struct clock_event_device *evt)
  45                 container_of(evt, struct ccount_timer, evt);
  46
  47         if (timer->irq_enabled) {
  48 -               disable_irq(evt->irq);
  49 +               disable_irq_nosync(evt->irq);
  50                 timer->irq_enabled = 0;
  51         }
  52         return 0;
  53 --
  54 2.19.1
  55