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[IPV4]: Use RCU locking in fib_rules.
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Signed-off-by: Robert Olsson <robert.olsson@its.uu.se>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Robert Olsson authored and David S. Miller committed Mar 21, 2006
1 parent d8dcffe commit 7b204af
Showing 1 changed file with 68 additions and 45 deletions.
113 changes: 68 additions & 45 deletions net/ipv4/fib_rules.c
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,8 @@
#include <linux/skbuff.h>
#include <linux/netlink.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/rcupdate.h>

#include <net/ip.h>
#include <net/protocol.h>
Expand All @@ -52,7 +54,7 @@

struct fib_rule
{
struct fib_rule *r_next;
struct hlist_node hlist;
atomic_t r_clntref;
u32 r_preference;
unsigned char r_table;
Expand All @@ -75,6 +77,7 @@ struct fib_rule
#endif
char r_ifname[IFNAMSIZ];
int r_dead;
struct rcu_head rcu;
};

static struct fib_rule default_rule = {
Expand All @@ -85,31 +88,31 @@ static struct fib_rule default_rule = {
};

static struct fib_rule main_rule = {
.r_next = &default_rule,
.r_clntref = ATOMIC_INIT(2),
.r_preference = 0x7FFE,
.r_table = RT_TABLE_MAIN,
.r_action = RTN_UNICAST,
};

static struct fib_rule local_rule = {
.r_next = &main_rule,
.r_clntref = ATOMIC_INIT(2),
.r_table = RT_TABLE_LOCAL,
.r_action = RTN_UNICAST,
};

static struct fib_rule *fib_rules = &local_rule;
static DEFINE_RWLOCK(fib_rules_lock);
struct hlist_head fib_rules;

/* writer func called from netlink -- rtnl_sem hold*/

int inet_rtm_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
{
struct rtattr **rta = arg;
struct rtmsg *rtm = NLMSG_DATA(nlh);
struct fib_rule *r, **rp;
struct fib_rule *r;
struct hlist_node *node;
int err = -ESRCH;

for (rp=&fib_rules; (r=*rp) != NULL; rp=&r->r_next) {
hlist_for_each_entry(r, node, &fib_rules, hlist) {
if ((!rta[RTA_SRC-1] || memcmp(RTA_DATA(rta[RTA_SRC-1]), &r->r_src, 4) == 0) &&
rtm->rtm_src_len == r->r_src_len &&
rtm->rtm_dst_len == r->r_dst_len &&
Expand All @@ -126,10 +129,8 @@ int inet_rtm_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
if (r == &local_rule)
break;

write_lock_bh(&fib_rules_lock);
*rp = r->r_next;
hlist_del_rcu(&r->hlist);
r->r_dead = 1;
write_unlock_bh(&fib_rules_lock);
fib_rule_put(r);
err = 0;
break;
Expand All @@ -150,21 +151,30 @@ static struct fib_table *fib_empty_table(void)
return NULL;
}

static inline void fib_rule_put_rcu(struct rcu_head *head)
{
struct fib_rule *r = container_of(head, struct fib_rule, rcu);
kfree(r);
}

void fib_rule_put(struct fib_rule *r)
{
if (atomic_dec_and_test(&r->r_clntref)) {
if (r->r_dead)
kfree(r);
call_rcu(&r->rcu, fib_rule_put_rcu);
else
printk("Freeing alive rule %p\n", r);
}
}

/* writer func called from netlink -- rtnl_sem hold*/

int inet_rtm_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
{
struct rtattr **rta = arg;
struct rtmsg *rtm = NLMSG_DATA(nlh);
struct fib_rule *r, *new_r, **rp;
struct fib_rule *r, *new_r, *last = NULL;
struct hlist_node *node = NULL;
unsigned char table_id;

if (rtm->rtm_src_len > 32 || rtm->rtm_dst_len > 32 ||
Expand All @@ -188,6 +198,7 @@ int inet_rtm_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
if (!new_r)
return -ENOMEM;
memset(new_r, 0, sizeof(*new_r));

if (rta[RTA_SRC-1])
memcpy(&new_r->r_src, RTA_DATA(rta[RTA_SRC-1]), 4);
if (rta[RTA_DST-1])
Expand Down Expand Up @@ -220,28 +231,28 @@ int inet_rtm_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
if (rta[RTA_FLOW-1])
memcpy(&new_r->r_tclassid, RTA_DATA(rta[RTA_FLOW-1]), 4);
#endif
r = container_of(fib_rules.first, struct fib_rule, hlist);

rp = &fib_rules;
if (!new_r->r_preference) {
r = fib_rules;
if (r && (r = r->r_next) != NULL) {
rp = &fib_rules->r_next;
if (r && r->hlist.next != NULL) {
r = container_of(r->hlist.next, struct fib_rule, hlist);
if (r->r_preference)
new_r->r_preference = r->r_preference - 1;
}
}

while ( (r = *rp) != NULL ) {
hlist_for_each_entry(r, node, &fib_rules, hlist) {
if (r->r_preference > new_r->r_preference)
break;
rp = &r->r_next;
last = r;
}

new_r->r_next = r;
atomic_inc(&new_r->r_clntref);
write_lock_bh(&fib_rules_lock);
*rp = new_r;
write_unlock_bh(&fib_rules_lock);

if (last)
hlist_add_after_rcu(&last->hlist, &new_r->hlist);
else
hlist_add_before_rcu(&new_r->hlist, &r->hlist);

return 0;
}

Expand All @@ -254,30 +265,30 @@ u32 fib_rules_tclass(struct fib_result *res)
}
#endif

/* callers should hold rtnl semaphore */

static void fib_rules_detach(struct net_device *dev)
{
struct hlist_node *node;
struct fib_rule *r;

for (r=fib_rules; r; r=r->r_next) {
if (r->r_ifindex == dev->ifindex) {
write_lock_bh(&fib_rules_lock);
hlist_for_each_entry(r, node, &fib_rules, hlist) {
if (r->r_ifindex == dev->ifindex)
r->r_ifindex = -1;
write_unlock_bh(&fib_rules_lock);
}

}
}

/* callers should hold rtnl semaphore */

static void fib_rules_attach(struct net_device *dev)
{
struct hlist_node *node;
struct fib_rule *r;

for (r=fib_rules; r; r=r->r_next) {
if (r->r_ifindex == -1 && strcmp(dev->name, r->r_ifname) == 0) {
write_lock_bh(&fib_rules_lock);
hlist_for_each_entry(r, node, &fib_rules, hlist) {
if (r->r_ifindex == -1 && strcmp(dev->name, r->r_ifname) == 0)
r->r_ifindex = dev->ifindex;
write_unlock_bh(&fib_rules_lock);
}
}
}

Expand All @@ -286,14 +297,17 @@ int fib_lookup(const struct flowi *flp, struct fib_result *res)
int err;
struct fib_rule *r, *policy;
struct fib_table *tb;
struct hlist_node *node;

u32 daddr = flp->fl4_dst;
u32 saddr = flp->fl4_src;

FRprintk("Lookup: %u.%u.%u.%u <- %u.%u.%u.%u ",
NIPQUAD(flp->fl4_dst), NIPQUAD(flp->fl4_src));
read_lock(&fib_rules_lock);
for (r = fib_rules; r; r=r->r_next) {

rcu_read_lock();

hlist_for_each_entry_rcu(r, node, &fib_rules, hlist) {
if (((saddr^r->r_src) & r->r_srcmask) ||
((daddr^r->r_dst) & r->r_dstmask) ||
(r->r_tos && r->r_tos != flp->fl4_tos) ||
Expand All @@ -309,14 +323,14 @@ FRprintk("tb %d r %d ", r->r_table, r->r_action);
policy = r;
break;
case RTN_UNREACHABLE:
read_unlock(&fib_rules_lock);
rcu_read_unlock();
return -ENETUNREACH;
default:
case RTN_BLACKHOLE:
read_unlock(&fib_rules_lock);
rcu_read_unlock();
return -EINVAL;
case RTN_PROHIBIT:
read_unlock(&fib_rules_lock);
rcu_read_unlock();
return -EACCES;
}

Expand All @@ -327,16 +341,16 @@ FRprintk("tb %d r %d ", r->r_table, r->r_action);
res->r = policy;
if (policy)
atomic_inc(&policy->r_clntref);
read_unlock(&fib_rules_lock);
rcu_read_unlock();
return 0;
}
if (err < 0 && err != -EAGAIN) {
read_unlock(&fib_rules_lock);
rcu_read_unlock();
return err;
}
}
FRprintk("FAILURE\n");
read_unlock(&fib_rules_lock);
rcu_read_unlock();
return -ENETUNREACH;
}

Expand Down Expand Up @@ -414,26 +428,35 @@ static __inline__ int inet_fill_rule(struct sk_buff *skb,
return -1;
}

/* callers should hold rtnl semaphore */

int inet_dump_rules(struct sk_buff *skb, struct netlink_callback *cb)
{
int idx;
int idx = 0;
int s_idx = cb->args[0];
struct fib_rule *r;
struct hlist_node *node;

rcu_read_lock();
hlist_for_each_entry(r, node, &fib_rules, hlist) {

read_lock(&fib_rules_lock);
for (r=fib_rules, idx=0; r; r = r->r_next, idx++) {
if (idx < s_idx)
continue;
if (inet_fill_rule(skb, r, cb, NLM_F_MULTI) < 0)
break;
idx++;
}
read_unlock(&fib_rules_lock);
rcu_read_unlock();
cb->args[0] = idx;

return skb->len;
}

void __init fib_rules_init(void)
{
INIT_HLIST_HEAD(&fib_rules);
hlist_add_head(&local_rule.hlist, &fib_rules);
hlist_add_after(&local_rule.hlist, &main_rule.hlist);
hlist_add_after(&main_rule.hlist, &default_rule.hlist);
register_netdevice_notifier(&fib_rules_notifier);
}

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