media: chips-media: wave5: Fix device cleanup order to prevent kernel panic

In the Linux kernel, the following vulnerability has been resolved:

media: chips-media: wave5: Fix device cleanup order to prevent kernel panic

Move video device unregistration to the beginning of the remove function

to ensure all video operations are stopped before cleaning up the worker

thread and disabling PM runtime. This prevents hardware register access

after the device has been powered down.

In polling mode, the hrtimer periodically triggers

wave5_vpu_timer_callback() which queues work to the kthread worker.

The worker executes wave5_vpu_irq_work_fn() which reads hardware

registers via wave5_vdi_read_register().

The original cleanup order disabled PM runtime and powered down hardware

before unregistering video devices. When autosuspend triggers and powers

off the hardware, the video devices are still registered and the worker

thread can still be triggered by the hrtimer, causing it to attempt

reading registers from powered-off hardware. This results in a bus error

(synchronous external abort) and kernel panic.

This causes random kernel panics during encoding operations:

Internal error: synchronous external abort: 0000000096000010

[#1] PREEMPT SMP

Modules linked in: wave5 rpmsg_ctrl rpmsg_char ...

CPU: 0 UID: 0 PID: 1520 Comm: vpu_irq_thread

Tainted: G M W

pc : wave5_vdi_read_register+0x10/0x38 [wave5]

lr : wave5_vpu_irq_work_fn+0x28/0x60 [wave5]

Call trace:

wave5_vdi_read_register+0x10/0x38 [wave5]

kthread_worker_fn+0xd8/0x238

kthread+0x104/0x120

ret_from_fork+0x10/0x20

Code: aa1e03e9 d503201f f9416800 8b214000 (b9400000)

---[ end trace 0000000000000000 ]---

Kernel panic - not syncing: synchronous external abort:

Fatal exception