On 25/07/2022 15:09, Michael Kelley (LINUX) wrote:
> [...]
>> +bool hv_ringbuffer_spinlock_busy(struct vmbus_channel *channel)
>> +{
>> +struct hv_ring_buffer_info *rinfo = >outbound;
>> +
>> +if (spin_is_locked(>ring_lock))
>> +return true;
>> +
>> +return false;
>
>
The Hyper-V framebuffer code registers a panic notifier in order
to try updating its fbdev if the kernel crashed. The notifier
callback is straightforward, but it calls the vmbus_sendpacket()
routine eventually, and such function takes a spinlock for the
ring buffer operations.
Panic path runs in
