On Fri, 1 Feb 2019, Hannes Reinecke wrote:

Thing is, if we have _managed_ CPU hotplug (ie if the hardware provides some
means of quiescing the CPU before hotplug) then the whole thing is trivial;
disable SQ and wait for all outstanding commands to complete.
Then trivially all requests are completed and the issue is resolved.
Even with todays infrastructure.

And I'm not sure if we can handle surprise CPU hotplug at all, given all the
possible race conditions.
But then I might be wrong.

The kernel would completely fall apart when a CPU would vanish by surprise,
i.e. uncontrolled by the kernel. Then the SCSI driver exploding would be
the least of our problems.

Thanks,

	tglx