From: Jon Fraser <jfraser@xxxxxxxxxxxx>
CPU interrupts need to be disabled on a cpu being taken down.
When a cpu is hot-plugged out of the system the following sequence occurs.
On the CPU where the hotplug sequence was initiated:
cpu_down
_cpu_down {
__cpu_notify(CPU_DOWN_PREPARE
__stop_machine(take_cpu_down
wait for cpu to run disable code.
__cpu_die
}
On the CPU being disabled:
take_cpu_down
__cpu_disable {
mp_ops->cpu_disable
bmips_cpu_disable
clear_c0_status(IE_IRQ5) (added)
cpu_notify(CPU_DYING...
}
Before the cpu_notifier is called with CPU_DYING, all interrupts on the
dying cpu must be disabled. This guarantees that before tick_notify is
called with the CPU_DYING event and sets the clock device pointer to
NULL, there can not be any more clock interrupts.
When this wasn't done, an unfortunately-timed timer interrupt sometimes
caused hangs immediately prior to system suspend:
Debug PM is not enabled. To enable partial suspend, rebuild kernel with CONFIG_PM_DEBUG
Pass 1 out of 1,PM: Syncing filesystems ... mode=none, tp1=done.
1, flags=5, cycle_tp=, sleep=
Freezing user space processes ... (elapsed 0.01 seconds) done.
Freezing remaining freezable tasks ... (elapsed 0.01 seconds) done.
PM: suspend of devices complete after 54.199 msecs
PM: late suspend of devices complete after 0.172 msecs
Disabling non-boot CPUs ...
SMP: CPU1 is offline
INFO: rcu_sched detected stalls on CPUs/tasks: { 3} (detected by 0, t=62537 jiffies)
Call Trace:
[<804baa78>] dump_stack+0x8/0x34
[<8008a2d8>] __rcu_pending+0x4b8/0x55c
[<8008adf4>] rcu_check_callbacks+0x78/0x180
[<80037830>] update_process_times+0x40/0x6c
[<80072fe4>] tick_sched_timer+0x74/0xe4
[<80050180>] __run_hrtimer.clone.30+0x64/0x140
[<80051150>] hrtimer_interrupt+0x19c/0x4bc
[<8000cdb8>] c0_compare_interrupt+0x50/0x88
[<80081b18>] handle_irq_event_percpu+0x5c/0x2f4
[<80086490>] handle_percpu_irq+0x8c/0xc0
[<800811b4>] generic_handle_irq+0x34/0x54
[<800067dc>] do_IRQ+0x18/0x2c
[<8000375c>] plat_irq_dispatch+0xd0/0x128
[<80004a04>] ret_from_irq+0x0/0x4
[<80004c40>] r4k_wait+0x20/0x40
[<80006b6c>] cpu_idle+0x98/0xf0
[<805d3988>] start_kernel+0x424/0x440
Signed-off-by: Jon Fraser <jfraser@xxxxxxxxxxxx>
Signed-off-by: Kevin Cernekee <cernekee@xxxxxxxxx>
---
arch/mips/kernel/smp-bmips.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/mips/kernel/smp-bmips.c b/arch/mips/kernel/smp-bmips.c
index 887c3ea..f7b1bee 100644
--- a/arch/mips/kernel/smp-bmips.c
+++ b/arch/mips/kernel/smp-bmips.c
@@ -375,6 +375,7 @@ static int bmips_cpu_disable(void)
set_cpu_online(cpu, false);
cpu_clear(cpu, cpu_callin_map);
+ clear_c0_status(IE_IRQ5);
local_flush_tlb_all();
local_flush_icache_range(0, ~0);
--
2.1.1
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