| Message ID | 1493399069-31743-1-git-send-email-xiyou.wangcong@gmail.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On 28.04.2017 19:04, Cong Wang wrote: > 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 <xiyou.wangcong@gmail.com> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
On Fri, 2017-04-28 at 10:04 -0700, Cong Wang wrote: > 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 <xiyou.wangcong@gmail.com> > --- > net/ipv4/ip_sockglue.c | 9 +-------- > 1 file changed, 1 insertion(+), 8 deletions(-) > > diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c > index 1d46d05..4c25458 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); > @@ -381,7 +376,6 @@ int ip_ra_control(struct sock *sk, unsigned char on, > } > } > if (!new_ra) { > - spin_unlock_bh(&ip_ra_lock); > return -ENOBUFS; > } Minor point : You could have removed the {} Acked-by: Eric Dumazet <edumazet@google.com> Thanks !
From: Cong Wang <xiyou.wangcong@gmail.com> Date: Fri, 28 Apr 2017 10:04:29 -0700 > 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 <xiyou.wangcong@gmail.com> Applied.
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index 1d46d05..4c25458 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); @@ -381,7 +376,6 @@ int ip_ra_control(struct sock *sk, unsigned char on, } } if (!new_ra) { - spin_unlock_bh(&ip_ra_lock); return -ENOBUFS; } new_ra->sk = sk; @@ -390,7 +384,6 @@ int ip_ra_control(struct sock *sk, unsigned char on, RCU_INIT_POINTER(new_ra->next, ra); rcu_assign_pointer(*rap, new_ra); sock_hold(sk); - spin_unlock_bh(&ip_ra_lock); return 0; }
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 <xiyou.wangcong@gmail.com> --- net/ipv4/ip_sockglue.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-)