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Gleb Smirnoff authored
Just trust the pcb database, that if we did in_pcbref(), no way an inpcb can go away. And if we never put a dropped inpcb on our queue, and tcp_discardcb() always removes an inpcb to be dropped from the queue, then any inpcb on the queue is valid. Now, to solve LOR between inpcb lock and HPTS queue lock do the following trick. When we are about to process a certain time slot, take the full queue of the head list into on stack list, drop the HPTS lock and work on our queue. This of course opens a race when an inpcb is being removed from the on stack queue, which was already mentioned in comments. To address this race introduce generation count into queues. If we want to remove an inpcb with generation count mismatch, we can't do that, we can only mark it with desired new time slot or -1 for remove. Reviewed by: rrs Differential revision: https://reviews.freebsd.org/D33026
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