[PATCH 1/1] thermal/sysfs: Clear the slot left in cooling_device_attr_groups

[Di Shen]

There's a space allocated for cooling_device_stats_attr_group within co-
oling_device_attr_groups. This space is shared by all cooling devices.

If not clear this space before cooling_device_stats_attr_group is initi-
alized, the next cooling device will still create stats sysfs file node.
At this time, read or write related nodes will cause kernel crash.

[exception_reboot_reason]: kernel_crash
[exception_panic_reason]: Fatal exception
[exception_time]: 2022-06-07_06-32-25
[exception_file_info]: not-bugon
[exception_task_id]: 3154
[exception_task_family]: [cat, 3154][sh, 2597][sh, 2362][adbd, 1804]
[exception_pc_symbol]: [<747516ae>] _raw_spin_lock+0x20/0x60
[exception_stack_info]: [<4cbe9ac1>] prepare_exception_info+0x19c/0x1a4
[<03041be7>] sysdump_panic_event+0x57c/0x6f4
[<b16f865e>] atomic_notifier_call_chain+0x48/0x7c
[<5baac8d4>] panic+0x1b4/0x3c8
[<9d287b0f>] arm_notify_die+0x0/0x78
[<094fc22c>] __do_kernel_fault+0x94/0xa4
[<3b4b69a4>] do_page_fault+0xd4/0x364
[<23793e7a>] do_translation_fault+0x38/0xc0
[<6e5cc52a>] do_DataAbort+0x4c/0xd0
[<a28c16b8>] __dabt_svc+0x5c/0xa0
[<747516ae>] _raw_spin_lock+0x20/0x60
[<9a9e4cd4>] time_in_state_ms_show+0x28/0x148
[<cb78325e>] dev_attr_show+0x38/0x64
[<aea3e364>] sysfs_kf_seq_show+0x8c/0xf0
[<c0a843ab>] seq_read+0x244/0x620
[<b316b374>] vfs_read+0xd8/0x218
[<3aebf5fa>] sys_read+0x80/0xe4
[<7cf100f5>] ret_fast_syscall+0x0/0x28
[<08cbe22f>] 0xbe8c1198

So clear the slot left in cooling_device_attr_groups before cooling_dev-
ice_stats_attr_group is initialized to avoid kernel crash.

Signed-off-by: Di Shen <di.shen@xxxxxxxxxx>
---
 drivers/thermal/thermal_sysfs.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c
index 1c4aac8464a7..fbc3dbc85841 100644
--- a/drivers/thermal/thermal_sysfs.c
+++ b/drivers/thermal/thermal_sysfs.c
@@ -817,6 +817,11 @@ static void cooling_device_stats_setup(struct thermal_cooling_device *cdev)
 	unsigned long states;
 	int var;
 
+	/* Clear the slot left in cooling_device_attr_groups */
+	var = ARRAY_SIZE(cooling_device_attr_groups) - 2;
+	if (cooling_device_attr_groups[var])
+		cooling_device_attr_groups[var] = NULL;
+
 	if (cdev->ops->get_max_state(cdev, &states))
 		return;
 
-- 
2.17.1