ipv6: addrconf: cleanup locking in ipv6_add_addr

Browse source

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 3ad7d2468f ("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 3ad7d2468f 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>

...

This commit is contained in:

David Ahern 2017-10-18 09:56:52 -07:00 • committed by David S. Miller

parent 6b1f8edaba

commit f3d9832e56

1 changed files with 60 additions and 44 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

104

net/ipv6/addrconf.c

View file