Potential races in SIGIO vs Epoll order

[Anton Ivanov]

Hi all,

I got around to look at the race discovered by YiFei Zhu in http://lists.infradead.org/pipermail/linux-um/2021-April/001396.html

While UML works using an epoll helper to generate SIGIO, it is ~ 5 times slower compared to enabling async IO. So this is not usable as the primary mode of operation for the interrupt controller.

I am going to play with it a bit further and try get it to do a "epoll not serviced" check only occasionally - to handle errors and IRQ controller stalls.

Brgds,

-- 
Anton R. Ivanov
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