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mpls: Cleanup the rcu usage in the code.
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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" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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@ebiederm @davem330
ebiederm authored and davem330 committed Mar 8, 2015
1 parent d865616 commit 19d0c34
Showing 1 changed file with 47 additions and 26 deletions.
73 changes: 47 additions & 26 deletions net/mpls/af_mpls.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand Down Expand Up @@ -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;

Expand Down Expand Up @@ -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;
}

Expand All @@ -287,16 +289,22 @@ 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;
}

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;
Expand Down Expand Up @@ -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;

Expand All @@ -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);

Expand Down Expand Up @@ -406,14 +415,16 @@ static int mpls_route_del(struct mpls_route_config *cfg)

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;
}
Expand Down Expand Up @@ -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;

Expand All @@ -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;
Expand All @@ -692,6 +705,8 @@ static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event,
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();
Expand All @@ -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;

Expand Down Expand Up @@ -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);
Expand All @@ -790,15 +807,15 @@ 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);
}

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 */
Expand All @@ -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();

Expand Down Expand Up @@ -903,15 +920,17 @@ 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;

table = net->mpls.ctl->ctl_table_arg;
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.
Expand All @@ -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 = {
Expand Down

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