[PATCH AUTOSEL 6.2 10/13] LoongArch: Only call get_timer_irq() once in constant_clockevent_init()

Sasha Levin
2023-03-14T12:46:00Z

From: Tiezhu Yang <yangtiezhu@loongson.cn>

[ Upstream commit bb7a78e343468873bf00b2b181fcfd3c02d8cb56 ]

Under CONFIG_DEBUG_ATOMIC_SLEEP=y and CONFIG_DEBUG_PREEMPT=y, we can see
the following messages on LoongArch, this is because using might_sleep()
in preemption disable context.

[ 0.001127] smp: Bringing up secondary CPUs ...
[ 0.001222] Booting CPU#1...
[ 0.001244] 64-bit Loongson Processor probed (LA464 Core)
[ 0.001247] CPU1 revision is: 0014c012 (Loongson-64bit)
[ 0.001250] FPU1 revision is: 00000000
[ 0.001252] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:283
[ 0.001255] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/1
[ 0.001257] preempt_count: 1, expected: 0
[ 0.001258] RCU nest depth: 0, expected: 0
[ 0.001259] Preemption disabled at:
[ 0.001261] [<9000000000223800>] arch_dup_task_struct+0x20/0x110
[ 0.001272] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.2.0-rc7+ #43
[ 0.001275] Hardware name: Loongson Loongson-3A5000-7A1000-1w-A2101/Loongson-LS3A5000-7A1000-1w-A2101, BIOS vUDK2018-LoongArch-V4.0.05132-beta10 12/13/202
[ 0.001277] Stack : 0072617764726148 0000000000000000 9000000000222f1c 90000001001e0000
[ 0.001286] 90000001001e3be0 90000001001e3be8 0000000000000000 0000000000000000
[ 0.001292] 90000001001e3be8 0000000000000040 90000001001e3cb8 90000001001e3a50
[ 0.001297] 9000000001642000 90000001001e3be8 be694d10ce4139dd 9000000100174500
[ 0.001303] 0000000000000001 0000000000000001 00000000ffffe0a2 0000000000000020
[ 0.001309] 000000000000002f 9000000001354116 00000000056b0000 ffffffffffffffff
[ 0.001314] 0000000000000000 0000000000000000 90000000014f6e90 9000000001642000
[ 0.001320] 900000000022b69c 0000000000000001 0000000000000000 9000000001736a90
[ 0.001325] 9000000100038000 0000000000000000 9000000000222f34 0000000000000000
[ 0.001331] 00000000000000b0 0000000000000004 0000000000000000 0000000000070000
[ 0.001337] ...
[ 0.001339] Call Trace:
[ 0.001342] [<9000000000222f34>] show_stack+0x5c/0x180
[ 0.001346] [<90000000010bdd80>] dump_stack_lvl+0x60/0x88
[ 0.001352] [<9000000000266418>] __might_resched+0x180/0x1cc
[ 0.001356] [<90000000010c742c>] mutex_lock+0x20/0x64
[ 0.001359] [<90000000002a8ccc>] irq_find_matching_fwspec+0x48/0x124
[ 0.001364] [<90000000002259c4>] constant_clockevent_init+0x68/0x204
[ 0.001368] [<900000000022acf4>] start_secondary+0x40/0xa8
[ 0.001371] [<90000000010c0124>] smpboot_entry+0x60/0x64

Here are the complete call chains:

smpboot_entry()
start_secondary()
constant_clockevent_init()
get_timer_irq()
irq_find_matching_fwnode()
irq_find_matching_fwspec()
mutex_lock()
might_sleep()
__might_sleep()
__might_resched()

In order to avoid the above issue, we should break the call chains,
using timer_irq_installed variable as check condition to only call
get_timer_irq() once in constant_clockevent_init() is a simple and
proper way.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/loongarch/kernel/time.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/loongarch/kernel/time.c b/arch/loongarch/kernel/time.c
index a6576dea590c0..4351f69d99501 100644
--- a/arch/loongarch/kernel/time.c
+++ b/arch/loongarch/kernel/time.c
@@ -140,16 +140,17 @@ static int get_timer_irq(void)

int constant_clockevent_init(void)
{
- int irq;
unsigned int cpu = smp_processor_id();
unsigned long min_delta = 0x600;
unsigned long max_delta = (1UL << 48) - 1;
struct clock_event_device *cd;
- static int timer_irq_installed = 0;
+ static int irq = 0, timer_irq_installed = 0;

- irq = get_timer_irq();
- if (irq < 0)
- pr_err("Failed to map irq %d (timer)\n", irq);
+ if (!timer_irq_installed) {
+ irq = get_timer_irq();
+ if (irq < 0)
+ pr_err("Failed to map irq %d (timer)\n", irq);
+ }

cd = &per_cpu(constant_clockevent_device, cpu);

--
2.39.2