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ipv6: mcast: RCU conversion
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ipv6_sk_mc_lock rwlock becomes a spinlock.

readers (inet6_mc_check()) now takes rcu_read_lock() instead of read
lock. Writers dont need to disable BH anymore.

struct ipv6_mc_socklist objects are reclaimed after one RCU grace
period.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Eric Dumazet authored and David S. Miller committed Nov 24, 2010
1 parent 2757a15 commit 456b61b
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Showing 3 changed files with 47 additions and 33 deletions.
2 changes: 1 addition & 1 deletion include/linux/ipv6.h
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Original file line number Diff line number Diff line change
Expand Up @@ -364,7 +364,7 @@ struct ipv6_pinfo {

__u32 dst_cookie;

struct ipv6_mc_socklist *ipv6_mc_list;
struct ipv6_mc_socklist __rcu *ipv6_mc_list;
struct ipv6_ac_socklist *ipv6_ac_list;
struct ipv6_fl_socklist *ipv6_fl_list;

Expand Down
3 changes: 2 additions & 1 deletion include/net/if_inet6.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -89,10 +89,11 @@ struct ip6_sf_socklist {
struct ipv6_mc_socklist {
struct in6_addr addr;
int ifindex;
struct ipv6_mc_socklist *next;
struct ipv6_mc_socklist __rcu *next;
rwlock_t sflock;
unsigned int sfmode; /* MCAST_{INCLUDE,EXCLUDE} */
struct ip6_sf_socklist *sflist;
struct rcu_head rcu;
};

struct ip6_sf_list {
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75 changes: 44 additions & 31 deletions net/ipv6/mcast.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -82,7 +82,7 @@ static void *__mld2_query_bugs[] __attribute__((__unused__)) = {
static struct in6_addr mld2_all_mcr = MLD2_ALL_MCR_INIT;

/* Big mc list lock for all the sockets */
static DEFINE_RWLOCK(ipv6_sk_mc_lock);
static DEFINE_SPINLOCK(ipv6_sk_mc_lock);

static void igmp6_join_group(struct ifmcaddr6 *ma);
static void igmp6_leave_group(struct ifmcaddr6 *ma);
Expand Down Expand Up @@ -123,6 +123,11 @@ int sysctl_mld_max_msf __read_mostly = IPV6_MLD_MAX_MSF;
* socket join on multicast group
*/

#define for_each_pmc_rcu(np, pmc) \
for (pmc = rcu_dereference(np->ipv6_mc_list); \
pmc != NULL; \
pmc = rcu_dereference(pmc->next))

int ipv6_sock_mc_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
{
struct net_device *dev = NULL;
Expand All @@ -134,15 +139,15 @@ int ipv6_sock_mc_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
if (!ipv6_addr_is_multicast(addr))
return -EINVAL;

read_lock_bh(&ipv6_sk_mc_lock);
for (mc_lst=np->ipv6_mc_list; mc_lst; mc_lst=mc_lst->next) {
rcu_read_lock();
for_each_pmc_rcu(np, mc_lst) {
if ((ifindex == 0 || mc_lst->ifindex == ifindex) &&
ipv6_addr_equal(&mc_lst->addr, addr)) {
read_unlock_bh(&ipv6_sk_mc_lock);
rcu_read_unlock();
return -EADDRINUSE;
}
}
read_unlock_bh(&ipv6_sk_mc_lock);
rcu_read_unlock();

mc_lst = sock_kmalloc(sk, sizeof(struct ipv6_mc_socklist), GFP_KERNEL);

Expand Down Expand Up @@ -186,33 +191,41 @@ int ipv6_sock_mc_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
return err;
}

write_lock_bh(&ipv6_sk_mc_lock);
spin_lock(&ipv6_sk_mc_lock);
mc_lst->next = np->ipv6_mc_list;
np->ipv6_mc_list = mc_lst;
write_unlock_bh(&ipv6_sk_mc_lock);
rcu_assign_pointer(np->ipv6_mc_list, mc_lst);
spin_unlock(&ipv6_sk_mc_lock);

rcu_read_unlock();

return 0;
}

static void ipv6_mc_socklist_reclaim(struct rcu_head *head)
{
kfree(container_of(head, struct ipv6_mc_socklist, rcu));
}
/*
* socket leave on multicast group
*/
int ipv6_sock_mc_drop(struct sock *sk, int ifindex, const struct in6_addr *addr)
{
struct ipv6_pinfo *np = inet6_sk(sk);
struct ipv6_mc_socklist *mc_lst, **lnk;
struct ipv6_mc_socklist *mc_lst;
struct ipv6_mc_socklist __rcu **lnk;
struct net *net = sock_net(sk);

write_lock_bh(&ipv6_sk_mc_lock);
for (lnk = &np->ipv6_mc_list; (mc_lst = *lnk) !=NULL ; lnk = &mc_lst->next) {
spin_lock(&ipv6_sk_mc_lock);
for (lnk = &np->ipv6_mc_list;
(mc_lst = rcu_dereference_protected(*lnk,
lockdep_is_held(&ipv6_sk_mc_lock))) !=NULL ;
lnk = &mc_lst->next) {
if ((ifindex == 0 || mc_lst->ifindex == ifindex) &&
ipv6_addr_equal(&mc_lst->addr, addr)) {
struct net_device *dev;

*lnk = mc_lst->next;
write_unlock_bh(&ipv6_sk_mc_lock);
spin_unlock(&ipv6_sk_mc_lock);

rcu_read_lock();
dev = dev_get_by_index_rcu(net, mc_lst->ifindex);
Expand All @@ -225,11 +238,12 @@ int ipv6_sock_mc_drop(struct sock *sk, int ifindex, const struct in6_addr *addr)
} else
(void) ip6_mc_leave_src(sk, mc_lst, NULL);
rcu_read_unlock();
sock_kfree_s(sk, mc_lst, sizeof(*mc_lst));
atomic_sub(sizeof(*mc_lst), &sk->sk_omem_alloc);
call_rcu(&mc_lst->rcu, ipv6_mc_socklist_reclaim);
return 0;
}
}
write_unlock_bh(&ipv6_sk_mc_lock);
spin_unlock(&ipv6_sk_mc_lock);

return -EADDRNOTAVAIL;
}
Expand Down Expand Up @@ -272,12 +286,13 @@ void ipv6_sock_mc_close(struct sock *sk)
struct ipv6_mc_socklist *mc_lst;
struct net *net = sock_net(sk);

write_lock_bh(&ipv6_sk_mc_lock);
while ((mc_lst = np->ipv6_mc_list) != NULL) {
spin_lock(&ipv6_sk_mc_lock);
while ((mc_lst = rcu_dereference_protected(np->ipv6_mc_list,
lockdep_is_held(&ipv6_sk_mc_lock))) != NULL) {
struct net_device *dev;

np->ipv6_mc_list = mc_lst->next;
write_unlock_bh(&ipv6_sk_mc_lock);
spin_unlock(&ipv6_sk_mc_lock);

rcu_read_lock();
dev = dev_get_by_index_rcu(net, mc_lst->ifindex);
Expand All @@ -290,11 +305,13 @@ void ipv6_sock_mc_close(struct sock *sk)
} else
(void) ip6_mc_leave_src(sk, mc_lst, NULL);
rcu_read_unlock();
sock_kfree_s(sk, mc_lst, sizeof(*mc_lst));

write_lock_bh(&ipv6_sk_mc_lock);
atomic_sub(sizeof(*mc_lst), &sk->sk_omem_alloc);
call_rcu(&mc_lst->rcu, ipv6_mc_socklist_reclaim);

spin_lock(&ipv6_sk_mc_lock);
}
write_unlock_bh(&ipv6_sk_mc_lock);
spin_unlock(&ipv6_sk_mc_lock);
}

int ip6_mc_source(int add, int omode, struct sock *sk,
Expand Down Expand Up @@ -328,8 +345,7 @@ int ip6_mc_source(int add, int omode, struct sock *sk,

err = -EADDRNOTAVAIL;

read_lock(&ipv6_sk_mc_lock);
for (pmc=inet6->ipv6_mc_list; pmc; pmc=pmc->next) {
for_each_pmc_rcu(inet6, pmc) {
if (pgsr->gsr_interface && pmc->ifindex != pgsr->gsr_interface)
continue;
if (ipv6_addr_equal(&pmc->addr, group))
Expand Down Expand Up @@ -428,7 +444,6 @@ int ip6_mc_source(int add, int omode, struct sock *sk,
done:
if (pmclocked)
write_unlock(&pmc->sflock);
read_unlock(&ipv6_sk_mc_lock);
read_unlock_bh(&idev->lock);
rcu_read_unlock();
if (leavegroup)
Expand Down Expand Up @@ -466,14 +481,13 @@ int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf)
dev = idev->dev;

err = 0;
read_lock(&ipv6_sk_mc_lock);

if (gsf->gf_fmode == MCAST_INCLUDE && gsf->gf_numsrc == 0) {
leavegroup = 1;
goto done;
}

for (pmc=inet6->ipv6_mc_list; pmc; pmc=pmc->next) {
for_each_pmc_rcu(inet6, pmc) {
if (pmc->ifindex != gsf->gf_interface)
continue;
if (ipv6_addr_equal(&pmc->addr, group))
Expand Down Expand Up @@ -521,7 +535,6 @@ int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf)
write_unlock(&pmc->sflock);
err = 0;
done:
read_unlock(&ipv6_sk_mc_lock);
read_unlock_bh(&idev->lock);
rcu_read_unlock();
if (leavegroup)
Expand Down Expand Up @@ -562,7 +575,7 @@ int ip6_mc_msfget(struct sock *sk, struct group_filter *gsf,
* so reading the list is safe.
*/

for (pmc=inet6->ipv6_mc_list; pmc; pmc=pmc->next) {
for_each_pmc_rcu(inet6, pmc) {
if (pmc->ifindex != gsf->gf_interface)
continue;
if (ipv6_addr_equal(group, &pmc->addr))
Expand Down Expand Up @@ -612,13 +625,13 @@ int inet6_mc_check(struct sock *sk, const struct in6_addr *mc_addr,
struct ip6_sf_socklist *psl;
int rv = 1;

read_lock(&ipv6_sk_mc_lock);
for (mc = np->ipv6_mc_list; mc; mc = mc->next) {
rcu_read_lock();
for_each_pmc_rcu(np, mc) {
if (ipv6_addr_equal(&mc->addr, mc_addr))
break;
}
if (!mc) {
read_unlock(&ipv6_sk_mc_lock);
rcu_read_unlock();
return 1;
}
read_lock(&mc->sflock);
Expand All @@ -638,7 +651,7 @@ int inet6_mc_check(struct sock *sk, const struct in6_addr *mc_addr,
rv = 0;
}
read_unlock(&mc->sflock);
read_unlock(&ipv6_sk_mc_lock);
rcu_read_unlock();

return rv;
}
Expand Down

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