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Re: [PATCH v4 06/10] evtchn: slightly defer lock acquire where possible

Hi Jan,

On 05/01/2021 13:11, Jan Beulich wrote:
port_is_valid() and evtchn_from_port() are fine to use without holding
any locks.

Per my remark in patch #1, currently, this only holds as long as we are checking the port for the current domain.

If it were a different domain, then the risk a risk that port_is_valid() may return valid and then invalid.

AFAICT, evtchn_close() may be called with d != current. So there is some racyness in the code as well.

Therefore, I will defer my ack until we agree on whether port_is_valid() can be used locklessly when current != domain.




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