genl: Allow concurrent genl callbacks.

All genl callbacks are serialized by genl-mutex. This can become
bottleneck in multi threaded case.
Following patch adds an parameter to genl_family so that a
particular family can get concurrent netlink callback without
genl_lock held.
New rw-sem is used to protect genl callback from genl family unregister.
in case of parallel_ops genl-family read-lock is taken for callbacks and
write lock is taken for register or unregistration for any family.
In case of locked genl family semaphore and gel-mutex is locked for
any openration.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/net/genetlink.h b/include/net/genetlink.h
index bdfbe68c1c3b..93024a47e0e2 100644
--- a/include/net/genetlink.h
+++ b/include/net/genetlink.h
@@ -50,6 +50,7 @@ struct genl_family {
         unsigned int            version;
         unsigned int            maxattr;
         bool                    netnsok;
+        bool                    parallel_ops;
         int                     (*pre_doit)(struct genl_ops *ops,
                                             struct sk_buff *skb,
                                             struct genl_info *info);