Re: [Qemu-devel] [RFC 22/38] cpu: update interrupt_request atomically

[Paolo Bonzini]

> This patch is needed as is. One real risk this is protecting
> against is the call of cpu_interrupt(cpu_foo) when the calling
> thread is not cpu_foo's thread--this write to interrupt_request
> might race with other writes, e.g. another call to cpu_interrupt
> from another thread, or the clearing of interrupt_request by
> cpu_foo.

But it should be protected by the iothread lock.  That requires
a lot of auditing. :(

I prefer to go with patch 23 first and then optimize things on
top (not that I don't like the optimization, since it also affects
KVM!). :)

Paolo

> Patch 23 fixes another issue--bootup hangs without it. The amount
> of code wrapped by the iothread lock can be reduced, though.
> Will fix.