[PATCH 1/4] um: irqs: process outstanding IRQs when unblocking signals

[Johannes Berg]

On Fri, 2023-10-20 at 12:38 +0200, Benjamin Beichler wrote:
> 
> Can you explain, why a time travel handler for stdin may be bad? It 
> sounds like you want to avoid it, but I see no immediate problem.
> 

I need to read the thread, but this one's easy ;-)

The thing is that on such a channel you don't send an ACK when you've
seen that there's something to handle. As a result, the sender will
continue running while you're trying to request a new schedule entry
from the controller. As a result, it may run past your new schedule
entry because it didn't know about it yet (this would likely bring down
the controller and crash the simulation), or the relative order of the
two entries is undefined, in the sense that it depends on the process
scheduling of the host.

johannes