rtnetlink: avoid RCU read lock when holding RTNL

When we call af_ops->set_link_af() we hold a RCU read lock
as we retrieve af_ops from the RCU protected list, but this
is unnecessary because we already hold RTNL lock, which is
the writer lock for protecting rtnl_af_ops, so it is safer
than RCU read lock. Similar for af_ops->validate_link_af().

This was not a problem until we begin to take mutex lock
down the path of ->set_link_af() in __ipv6_dev_mc_dec()
recently. We can just drop the RCU read lock there and
assert RTNL lock.

Reported-and-tested-by: [email protected]
Fixes: 63ed8de4be81 ("mld: add mc_lock for protecting per-interface mld data")
Tested-by: Taehee Yoo <[email protected]>
Signed-off-by: Cong Wang <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

0 files changed, 0 insertions, 0 deletions