igmp: RCU conversion of in_dev->mc_list
in_dev->mc_list is protected by one rwlock (in_dev->mc_list_lock).
This can easily be converted to a RCU protection.
Writers hold RTNL, so mc_list_lock is removed, not replaced by a
spinlock.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Cypher Wu <cypher.w@gmail.com>
Cc: Américo Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/igmp.h b/include/linux/igmp.h
index 93fc244..7d16467 100644
--- a/include/linux/igmp.h
+++ b/include/linux/igmp.h
@@ -167,10 +167,10 @@
*/
struct ip_mc_socklist {
- struct ip_mc_socklist *next;
+ struct ip_mc_socklist __rcu *next_rcu;
struct ip_mreqn multi;
unsigned int sfmode; /* MCAST_{INCLUDE,EXCLUDE} */
- struct ip_sf_socklist *sflist;
+ struct ip_sf_socklist __rcu *sflist;
struct rcu_head rcu;
};
@@ -186,11 +186,14 @@
struct ip_mc_list {
struct in_device *interface;
__be32 multiaddr;
+ unsigned int sfmode;
struct ip_sf_list *sources;
struct ip_sf_list *tomb;
- unsigned int sfmode;
unsigned long sfcount[2];
- struct ip_mc_list *next;
+ union {
+ struct ip_mc_list *next;
+ struct ip_mc_list __rcu *next_rcu;
+ };
struct timer_list timer;
int users;
atomic_t refcnt;
@@ -201,6 +204,7 @@
char loaded;
unsigned char gsquery; /* check source marks? */
unsigned char crcount;
+ struct rcu_head rcu;
};
/* V3 exponential field decoding */
diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index ccd5b07..380ba6b 100644
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h
@@ -52,9 +52,8 @@
atomic_t refcnt;
int dead;
struct in_ifaddr *ifa_list; /* IP ifaddr chain */
- rwlock_t mc_list_lock;
- struct ip_mc_list *mc_list; /* IP multicast filter chain */
- int mc_count; /* Number of installed mcasts */
+ struct ip_mc_list __rcu *mc_list; /* IP multicast filter chain */
+ int mc_count; /* Number of installed mcasts */
spinlock_t mc_tomb_lock;
struct ip_mc_list *mc_tomb;
unsigned long mr_v1_seen;
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index 1989cfd7..8945f9f 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -141,7 +141,7 @@
nodefrag:1;
int mc_index;
__be32 mc_addr;
- struct ip_mc_socklist *mc_list;
+ struct ip_mc_socklist __rcu *mc_list;
struct {
unsigned int flags;
unsigned int fragsize;
