From ba3f571d5dde27fc4ae83aabe2c06ff08087af49 Mon Sep 17 00:00:00 2001 From: WANG Cong Date: Fri, 28 Apr 2017 10:04:29 -0700 Subject: [PATCH] ipv4: get rid of ip_ra_lock After commit 1215e51edad1 ("ipv4: fix a deadlock in ip_ra_control") we always take RTNL lock for ip_ra_control() which is the only place we update the list ip_ra_chain, so the ip_ra_lock is no longer needed. As Eric points out, BH does not need to disable either, RCU readers don't care. Signed-off-by: Cong Wang Acked-by: Hannes Frederic Sowa Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/ip_sockglue.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index 1d46d05..ec4fe3d 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -330,7 +330,6 @@ int ip_cmsg_send(struct sock *sk, struct msghdr *msg, struct ipcm_cookie *ipc, sent to multicast group to reach destination designated router. */ struct ip_ra_chain __rcu *ip_ra_chain; -static DEFINE_SPINLOCK(ip_ra_lock); static void ip_ra_destroy_rcu(struct rcu_head *head) @@ -352,21 +351,17 @@ int ip_ra_control(struct sock *sk, unsigned char on, new_ra = on ? kmalloc(sizeof(*new_ra), GFP_KERNEL) : NULL; - spin_lock_bh(&ip_ra_lock); for (rap = &ip_ra_chain; - (ra = rcu_dereference_protected(*rap, - lockdep_is_held(&ip_ra_lock))) != NULL; + (ra = rtnl_dereference(*rap)) != NULL; rap = &ra->next) { if (ra->sk == sk) { if (on) { - spin_unlock_bh(&ip_ra_lock); kfree(new_ra); return -EADDRINUSE; } /* dont let ip_call_ra_chain() use sk again */ ra->sk = NULL; RCU_INIT_POINTER(*rap, ra->next); - spin_unlock_bh(&ip_ra_lock); if (ra->destructor) ra->destructor(sk); @@ -380,17 +375,14 @@ int ip_ra_control(struct sock *sk, unsigned char on, return 0; } } - if (!new_ra) { - spin_unlock_bh(&ip_ra_lock); + if (!new_ra) return -ENOBUFS; - } new_ra->sk = sk; new_ra->destructor = destructor; RCU_INIT_POINTER(new_ra->next, ra); rcu_assign_pointer(*rap, new_ra); sock_hold(sk); - spin_unlock_bh(&ip_ra_lock); return 0; } -- 2.7.4