llc: convert the socket list to RCU locking

For the reclamation phase we use the SLAB_DESTROY_BY_RCU mechanism,
which require some extra checks in the lookup code:

a) If the current socket was released, reallocated & inserted in
another list it will short circuit the iteration for the current list,
thus we need to restart the lookup.

b) If the current socket was released, reallocated & inserted in the
same list we just need to recheck it matches the look-up criteria and
if not we can skip to the next element.

In this case there is no need to restart the lookup, since sockets are
inserted at the start of the list and the worst that will happen is
that we will iterate throught some of the list elements more then
once.

Note that the /proc and multicast delivery was not yet converted to
RCU, it still uses spinlocks for protection.

Signed-off-by: Octavian Purdila <opurdila@ixiacom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 4 deletions

diff --git a/include/net/llc.h b/include/net/llc.h
index 7940da1..1559cf1 100644
--- a/include/net/llc.h
+++ b/include/net/llc.h
@@ -16,6 +16,7 @@
 #include <linux/if_ether.h>
 #include <linux/list.h>
 #include <linux/spinlock.h>
+#include <linux/rculist_nulls.h>
 
 #include <asm/atomic.h>
 
@@ -53,10 +54,8 @@ struct llc_sap {
 				     struct net_device *orig_dev);
 	struct llc_addr	 laddr;
 	struct list_head node;
-	struct {
-		rwlock_t	  lock;
-		struct hlist_head list;
-	} sk_list;
+	spinlock_t sk_lock;
+	struct hlist_nulls_head sk_list;
 };
 
 #define LLC_DEST_INVALID         0      /* Invalid LLC PDU type */