From: Eric W. Biederman Date: Sat, 7 Mar 2015 22:21:56 +0000 (-0600) Subject: mpls: Cleanup the rcu usage in the code. X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=19d0c341d9d5cd186661fef58e7264a9701ef71d;p=openwrt%2Fstaging%2Fblogic.git mpls: Cleanup the rcu usage in the code. Sparse was generating a lot of warnings mostly from missing annotations in the code. Add missing annotations and in a few cases tweak the code for performance by moving work before loops. This also fixes a problematic ommision of rcu_assign_pointer and rcu_dereference. Hopefully with complete rcu annotations any new rcu errors will stick out like a sore thumb. Signed-off-by: "Eric W. Biederman" Signed-off-by: David S. Miller --- diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c index 59cc32564d50..0f2833e1b233 100644 --- a/net/mpls/af_mpls.c +++ b/net/mpls/af_mpls.c @@ -24,7 +24,7 @@ #define MAX_VIA_ALEN (ALIGN(MAX_ADDR_LEN, sizeof(unsigned long))) struct mpls_route { /* next hop label forwarding entry */ - struct net_device *rt_dev; + struct net_device __rcu *rt_dev; struct rcu_head rt_rcu; u32 rt_label[MAX_NEW_LABELS]; u8 rt_protocol; /* routing protocol that set this entry */ @@ -152,7 +152,7 @@ static int mpls_forward(struct sk_buff *skb, struct net_device *dev, goto drop; /* Find the output device */ - out_dev = rt->rt_dev; + out_dev = rcu_dereference(rt->rt_dev); if (!mpls_output_possible(out_dev)) goto drop; @@ -269,13 +269,15 @@ static void mpls_route_update(struct net *net, unsigned index, struct net_device *dev, struct mpls_route *new, const struct nl_info *info) { + struct mpls_route __rcu **platform_label; struct mpls_route *rt, *old = NULL; ASSERT_RTNL(); - rt = net->mpls.platform_label[index]; - if (!dev || (rt && (rt->rt_dev == dev))) { - rcu_assign_pointer(net->mpls.platform_label[index], new); + platform_label = rtnl_dereference(net->mpls.platform_label); + rt = rtnl_dereference(platform_label[index]); + if (!dev || (rt && (rtnl_dereference(rt->rt_dev) == dev))) { + rcu_assign_pointer(platform_label[index], new); old = rt; } @@ -287,9 +289,14 @@ static void mpls_route_update(struct net *net, unsigned index, static unsigned find_free_label(struct net *net) { + struct mpls_route __rcu **platform_label; + size_t platform_labels; unsigned index; - for (index = 16; index < net->mpls.platform_labels; index++) { - if (!net->mpls.platform_label[index]) + + platform_label = rtnl_dereference(net->mpls.platform_label); + platform_labels = net->mpls.platform_labels; + for (index = 16; index < platform_labels; index++) { + if (!rtnl_dereference(platform_label[index])) return index; } return LABEL_NOT_SPECIFIED; @@ -297,6 +304,7 @@ static unsigned find_free_label(struct net *net) static int mpls_route_add(struct mpls_route_config *cfg) { + struct mpls_route __rcu **platform_label; struct net *net = cfg->rc_nlinfo.nl_net; struct net_device *dev = NULL; struct mpls_route *rt, *old; @@ -345,7 +353,8 @@ static int mpls_route_add(struct mpls_route_config *cfg) goto errout; err = -EEXIST; - old = net->mpls.platform_label[index]; + platform_label = rtnl_dereference(net->mpls.platform_label); + old = rtnl_dereference(platform_label[index]); if ((cfg->rc_nlflags & NLM_F_EXCL) && old) goto errout; @@ -366,7 +375,7 @@ static int mpls_route_add(struct mpls_route_config *cfg) for (i = 0; i < rt->rt_labels; i++) rt->rt_label[i] = cfg->rc_output_label[i]; rt->rt_protocol = cfg->rc_protocol; - rt->rt_dev = dev; + RCU_INIT_POINTER(rt->rt_dev, dev); rt->rt_via_family = cfg->rc_via_family; memcpy(rt->rt_via, cfg->rc_via, cfg->rc_via_alen); @@ -406,14 +415,16 @@ errout: static void mpls_ifdown(struct net_device *dev) { + struct mpls_route __rcu **platform_label; struct net *net = dev_net(dev); unsigned index; + platform_label = rtnl_dereference(net->mpls.platform_label); for (index = 0; index < net->mpls.platform_labels; index++) { - struct mpls_route *rt = net->mpls.platform_label[index]; + struct mpls_route *rt = rtnl_dereference(platform_label[index]); if (!rt) continue; - if (rt->rt_dev != dev) + if (rtnl_dereference(rt->rt_dev) != dev) continue; rt->rt_dev = NULL; } @@ -653,6 +664,7 @@ static int mpls_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh) static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event, u32 label, struct mpls_route *rt, int flags) { + struct net_device *dev; struct nlmsghdr *nlh; struct rtmsg *rtm; @@ -676,7 +688,8 @@ static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event, goto nla_put_failure; if (nla_put_via(skb, rt->rt_via_family, rt->rt_via, rt->rt_via_alen)) goto nla_put_failure; - if (rt->rt_dev && nla_put_u32(skb, RTA_OIF, rt->rt_dev->ifindex)) + dev = rtnl_dereference(rt->rt_dev); + if (dev && nla_put_u32(skb, RTA_OIF, dev->ifindex)) goto nla_put_failure; if (nla_put_labels(skb, RTA_DST, 1, &label)) goto nla_put_failure; @@ -692,6 +705,8 @@ nla_put_failure: static int mpls_dump_routes(struct sk_buff *skb, struct netlink_callback *cb) { struct net *net = sock_net(skb->sk); + struct mpls_route __rcu **platform_label; + size_t platform_labels; unsigned int index; ASSERT_RTNL(); @@ -700,9 +715,11 @@ static int mpls_dump_routes(struct sk_buff *skb, struct netlink_callback *cb) if (index < 16) index = 16; - for (; index < net->mpls.platform_labels; index++) { + platform_label = rtnl_dereference(net->mpls.platform_label); + platform_labels = net->mpls.platform_labels; + for (; index < platform_labels; index++) { struct mpls_route *rt; - rt = net->mpls.platform_label[index]; + rt = rtnl_dereference(platform_label[index]); if (!rt) continue; @@ -780,7 +797,7 @@ static int resize_platform_label_table(struct net *net, size_t limit) rt0 = mpls_rt_alloc(lo->addr_len); if (!rt0) goto nort0; - rt0->rt_dev = lo; + RCU_INIT_POINTER(rt0->rt_dev, lo); rt0->rt_protocol = RTPROT_KERNEL; rt0->rt_via_family = AF_PACKET; memcpy(rt0->rt_via, lo->dev_addr, lo->addr_len); @@ -790,7 +807,7 @@ static int resize_platform_label_table(struct net *net, size_t limit) rt2 = mpls_rt_alloc(lo->addr_len); if (!rt2) goto nort2; - rt2->rt_dev = lo; + RCU_INIT_POINTER(rt2->rt_dev, lo); rt2->rt_protocol = RTPROT_KERNEL; rt2->rt_via_family = AF_PACKET; memcpy(rt2->rt_via, lo->dev_addr, lo->addr_len); @@ -798,7 +815,7 @@ static int resize_platform_label_table(struct net *net, size_t limit) rtnl_lock(); /* Remember the original table */ - old = net->mpls.platform_label; + old = rtnl_dereference(net->mpls.platform_label); old_limit = net->mpls.platform_labels; /* Free any labels beyond the new table */ @@ -815,19 +832,19 @@ static int resize_platform_label_table(struct net *net, size_t limit) /* If needed set the predefined labels */ if ((old_limit <= LABEL_IPV6_EXPLICIT_NULL) && (limit > LABEL_IPV6_EXPLICIT_NULL)) { - labels[LABEL_IPV6_EXPLICIT_NULL] = rt2; + RCU_INIT_POINTER(labels[LABEL_IPV6_EXPLICIT_NULL], rt2); rt2 = NULL; } if ((old_limit <= LABEL_IPV4_EXPLICIT_NULL) && (limit > LABEL_IPV4_EXPLICIT_NULL)) { - labels[LABEL_IPV4_EXPLICIT_NULL] = rt0; + RCU_INIT_POINTER(labels[LABEL_IPV4_EXPLICIT_NULL], rt0); rt0 = NULL; } /* Update the global pointers */ net->mpls.platform_labels = limit; - net->mpls.platform_label = labels; + rcu_assign_pointer(net->mpls.platform_label, labels); rtnl_unlock(); @@ -903,6 +920,8 @@ static int mpls_net_init(struct net *net) static void mpls_net_exit(struct net *net) { + struct mpls_route __rcu **platform_label; + size_t platform_labels; struct ctl_table *table; unsigned int index; @@ -910,8 +929,8 @@ static void mpls_net_exit(struct net *net) unregister_net_sysctl_table(net->mpls.ctl); kfree(table); - /* An rcu grace period haselapsed since there was a device in - * the network namespace (and thus the last in fqlight packet) + /* An rcu grace period has passed since there was a device in + * the network namespace (and thus the last in flight packet) * left this network namespace. This is because * unregister_netdevice_many and netdev_run_todo has completed * for each network device that was in this network namespace. @@ -920,14 +939,16 @@ static void mpls_net_exit(struct net *net) * freeing the platform_label table. */ rtnl_lock(); - for (index = 0; index < net->mpls.platform_labels; index++) { - struct mpls_route *rt = net->mpls.platform_label[index]; - rcu_assign_pointer(net->mpls.platform_label[index], NULL); + platform_label = rtnl_dereference(net->mpls.platform_label); + platform_labels = net->mpls.platform_labels; + for (index = 0; index < platform_labels; index++) { + struct mpls_route *rt = rtnl_dereference(platform_label[index]); + RCU_INIT_POINTER(platform_label[index], NULL); mpls_rt_free(rt); } rtnl_unlock(); - kvfree(net->mpls.platform_label); + kvfree(platform_label); } static struct pernet_operations mpls_net_ops = {