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Gleb Smirnoff authored
With introduction of epoch(9) synchronization to network stack the inpcb database became protected by the network epoch together with static network data (interfaces, addresses, etc). However, inpcb aren't static in nature, they are created and destroyed all the time, which creates some traffic on the epoch(9) garbage collector. Fairly new feature of uma(9) - Safe Memory Reclamation allows to safely free memory in page-sized batches, with virtually zero overhead compared to uma_zfree(). However, unlike epoch(9), it puts stricter requirement on the access to the protected memory, needing the critical(9) section to access it. Details: - The database is already build on CK lists, thanks to epoch(9). - For write access nothing is changed. - For a lookup in the database SMR section is now required. Once the desired inpcb is found we need to transition from SMR section to r/w lock on the inpcb itself, with a check that inpcb isn't yet freed. This requires some compexity, since SMR section itself is a critical(9) section. The complexity is hidden from KPI users in inp_smr_lock(). - For a inpcb list traversal (a pcblist sysctl, or broadcast notification) also a new KPI is provided, that hides internals of the database - inp_next(struct inp_iterator *). Reviewed by: rrs Differential revision: https://reviews.freebsd.org/D33022
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