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Florian Westphal authored
switch to lockless lockup. write side now also increments sequence counter. On lookup, sample counter value and only take the lock if we did not find a match and the counter has changed. This avoids need to write to private area in normal (lookup) cases. In case we detect a writer (seqretry is true) we fall back to taking the readlock. The readlock is also used during dumps to ensure we get a consistent tree walk. Similar technique (rbtree+seqlock) was used by David Howells in rxrpc. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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