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Eric Dumazet authored
netdev_wait_allrefs() waits that all references to a device vanishes. It currently uses a _very_ pessimistic 250 ms delay between each probe. Some users reported that no more than 4 devices can be dismantled per second, this is a pretty serious problem for some setups. Most of the time, a refcount is about to be released by an RCU callback, that is still in flight because rollback_registered_many() uses a synchronize_rcu() call instead of rcu_barrier(). Problem is visible if number of online cpus is one, because synchronize_rcu() is then a no op. time to remove 50 ipip tunnels on a UP machine : before patch : real 11.910s after patch : real 1.250s Reported-by:
Nicolas Dichtel <nicolas.dichtel@6wind.com> Reported-by:
Octavian Purdila <opurdila@ixiacom.com> Reported-by:
Benjamin LaHaise <bcrl@kvack.org> Signed-off-by:
Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
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