Commit ba3f571d authored by WANG Cong's avatar WANG Cong Committed by David S. Miller

ipv4: get rid of ip_ra_lock

After commit 1215e51e ("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: default avatarCong Wang <xiyou.wangcong@gmail.com>
Acked-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5010e948
...@@ -330,7 +330,6 @@ int ip_cmsg_send(struct sock *sk, struct msghdr *msg, struct ipcm_cookie *ipc, ...@@ -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. sent to multicast group to reach destination designated router.
*/ */
struct ip_ra_chain __rcu *ip_ra_chain; struct ip_ra_chain __rcu *ip_ra_chain;
static DEFINE_SPINLOCK(ip_ra_lock);
static void ip_ra_destroy_rcu(struct rcu_head *head) static void ip_ra_destroy_rcu(struct rcu_head *head)
...@@ -352,21 +351,17 @@ int ip_ra_control(struct sock *sk, unsigned char on, ...@@ -352,21 +351,17 @@ int ip_ra_control(struct sock *sk, unsigned char on,
new_ra = on ? kmalloc(sizeof(*new_ra), GFP_KERNEL) : NULL; new_ra = on ? kmalloc(sizeof(*new_ra), GFP_KERNEL) : NULL;
spin_lock_bh(&ip_ra_lock);
for (rap = &ip_ra_chain; for (rap = &ip_ra_chain;
(ra = rcu_dereference_protected(*rap, (ra = rtnl_dereference(*rap)) != NULL;
lockdep_is_held(&ip_ra_lock))) != NULL;
rap = &ra->next) { rap = &ra->next) {
if (ra->sk == sk) { if (ra->sk == sk) {
if (on) { if (on) {
spin_unlock_bh(&ip_ra_lock);
kfree(new_ra); kfree(new_ra);
return -EADDRINUSE; return -EADDRINUSE;
} }
/* dont let ip_call_ra_chain() use sk again */ /* dont let ip_call_ra_chain() use sk again */
ra->sk = NULL; ra->sk = NULL;
RCU_INIT_POINTER(*rap, ra->next); RCU_INIT_POINTER(*rap, ra->next);
spin_unlock_bh(&ip_ra_lock);
if (ra->destructor) if (ra->destructor)
ra->destructor(sk); ra->destructor(sk);
...@@ -380,17 +375,14 @@ int ip_ra_control(struct sock *sk, unsigned char on, ...@@ -380,17 +375,14 @@ int ip_ra_control(struct sock *sk, unsigned char on,
return 0; return 0;
} }
} }
if (!new_ra) { if (!new_ra)
spin_unlock_bh(&ip_ra_lock);
return -ENOBUFS; return -ENOBUFS;
}
new_ra->sk = sk; new_ra->sk = sk;
new_ra->destructor = destructor; new_ra->destructor = destructor;
RCU_INIT_POINTER(new_ra->next, ra); RCU_INIT_POINTER(new_ra->next, ra);
rcu_assign_pointer(*rap, new_ra); rcu_assign_pointer(*rap, new_ra);
sock_hold(sk); sock_hold(sk);
spin_unlock_bh(&ip_ra_lock);
return 0; return 0;
} }
......
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