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| H A D | addrconf.c | diff f3d9832e56c48e4ca50bab0457e21bcaade4536d Wed Oct 18 11:56:52 CDT 2017 David Ahern <dsahern@gmail.com> ipv6: addrconf: cleanup locking in ipv6_add_addr
ipv6_add_addr is called in process context with rtnl lock held
(e.g., manual config of an address) or during softirq processing
(e.g., autoconf and address from a router advertisement).
Currently, ipv6_add_addr calls rcu_read_lock_bh shortly after entry
and does not call unlock until exit, minus the call around the address
validator notifier. Similarly, addrconf_hash_lock is taken after the
validator notifier and held until exit. This forces the allocation of
inet6_ifaddr to always be atomic.
Refactor ipv6_add_addr as follows:
1. add an input boolean to discriminate the call path (process context
or softirq). This new flag controls whether the alloc can be done
with GFP_KERNEL or GFP_ATOMIC.
2. Move the rcu_read_lock_bh and unlock calls only around functions that
do rcu updates.
3. Remove the in6_dev_hold and put added by 3ad7d2468f79f ("Ipvlan should
return an error when an address is already in use."). This was done
presumably because rcu_read_unlock_bh needs to be called before calling
the validator. Since rcu_read_lock is not needed before the validator
runs revert the hold and put added by 3ad7d2468f79f and only do the
hold when setting ifp->idev.
4. move duplicate address check and insertion of new address in the global
address hash into a helper. The helper is called after an ifa is
allocated and filled in.
This allows the ifa for manually configured addresses to be done with
GFP_KERNEL and reduces the overall amount of time with rcu_read_lock held
and hash table spinlock held.
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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