Currently there are only two tc actions lockless: gact and mirred. But they are questionable because we don't have anything to prevent a parallel update on an existing tc action in hash table while reading it on fast path, this could be a problem when a tc action becomes complex.
This patchset introduces a few new tc action API's based on RCU so that the fast path could now really be protected by RCU and we can update existing tc actions safely and race-freely. Obviously this is still _not_ complete yet, I only modified mirred action to show the use case of the new API's, all the rest actions could switch to the new API's too. The new API's are a bit ugly too, any suggestion to improve them is welcome. I tested mirred action with a few test cases, so far so good, at least no obvious bugs. ;) Cong Wang (6): net_sched: use RCU for action hash table net_sched: introduce tcf_hash_replace() net_sched: return NULL in tcf_hash_check() net_sched: introduce tcf_hash_copy() net_sched: use rcu in fast path net_sched: switch to RCU API for act_mirred include/net/act_api.h | 3 +++ net/sched/act_api.c | 59 +++++++++++++++++++++++++++++++++++++++++++------- net/sched/act_mirred.c | 41 ++++++++++++++++------------------- 3 files changed, 73 insertions(+), 30 deletions(-) -- 2.1.0
