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ipvs: convert dests to rcu
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In previous commits the schedulers started to access
svc->destinations with _rcu list traversal primitives
because the IP_VS_WAIT_WHILE macro still plays the role of
grace period. Now it is time to finish the updating part,
i.e. adding and deleting of dests with _rcu suffix before
removing the IP_VS_WAIT_WHILE in next commit.

We use the same rule for conns as for the
schedulers: dests can be searched in RCU read-side critical
section where ip_vs_dest_hold can be called by ip_vs_bind_dest.

Some things are not perfect, for example, calling
functions like ip_vs_lookup_dest from updating code under
RCU, just because we use some function both from reader
and from updater.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
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Julian Anastasov authored and Pablo Neira Ayuso committed Apr 1, 2013
1 parent ba3a3ce commit 413c2d0
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Showing 4 changed files with 27 additions and 26 deletions.
2 changes: 1 addition & 1 deletion include/net/ip_vs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1434,7 +1434,7 @@ extern struct ip_vs_dest *
ip_vs_find_dest(struct net *net, int af, const union nf_inet_addr *daddr,
__be16 dport, const union nf_inet_addr *vaddr, __be16 vport,
__u16 protocol, __u32 fwmark, __u32 flags);
extern struct ip_vs_dest *ip_vs_try_bind_dest(struct ip_vs_conn *cp);
extern void ip_vs_try_bind_dest(struct ip_vs_conn *cp);

static inline void ip_vs_dest_hold(struct ip_vs_dest *dest)
{
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8 changes: 5 additions & 3 deletions net/netfilter/ipvs/ip_vs_conn.c
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Original file line number Diff line number Diff line change
Expand Up @@ -611,10 +611,11 @@ ip_vs_bind_dest(struct ip_vs_conn *cp, struct ip_vs_dest *dest)
* Check if there is a destination for the connection, if so
* bind the connection to the destination.
*/
struct ip_vs_dest *ip_vs_try_bind_dest(struct ip_vs_conn *cp)
void ip_vs_try_bind_dest(struct ip_vs_conn *cp)
{
struct ip_vs_dest *dest;

rcu_read_lock();
dest = ip_vs_find_dest(ip_vs_conn_net(cp), cp->af, &cp->daddr,
cp->dport, &cp->vaddr, cp->vport,
cp->protocol, cp->fwmark, cp->flags);
Expand All @@ -624,7 +625,8 @@ struct ip_vs_dest *ip_vs_try_bind_dest(struct ip_vs_conn *cp)
spin_lock(&cp->lock);
if (cp->dest) {
spin_unlock(&cp->lock);
return dest;
rcu_read_unlock();
return;
}

/* Applications work depending on the forwarding method
Expand All @@ -648,7 +650,7 @@ struct ip_vs_dest *ip_vs_try_bind_dest(struct ip_vs_conn *cp)
if (pd && atomic_read(&pd->appcnt))
ip_vs_bind_app(cp, pd->pp);
}
return dest;
rcu_read_unlock();
}


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32 changes: 17 additions & 15 deletions net/netfilter/ipvs/ip_vs_ctl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -565,8 +565,8 @@ bool ip_vs_has_real_service(struct net *net, int af, __u16 protocol,
return false;
}

/*
* Lookup destination by {addr,port} in the given service
/* Lookup destination by {addr,port} in the given service
* Called under RCU lock.
*/
static struct ip_vs_dest *
ip_vs_lookup_dest(struct ip_vs_service *svc, const union nf_inet_addr *daddr,
Expand All @@ -577,7 +577,7 @@ ip_vs_lookup_dest(struct ip_vs_service *svc, const union nf_inet_addr *daddr,
/*
* Find the destination for the given service
*/
list_for_each_entry(dest, &svc->destinations, n_list) {
list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
if ((dest->af == svc->af)
&& ip_vs_addr_equal(svc->af, &dest->addr, daddr)
&& (dest->port == dport)) {
Expand All @@ -591,10 +591,11 @@ ip_vs_lookup_dest(struct ip_vs_service *svc, const union nf_inet_addr *daddr,

/*
* Find destination by {daddr,dport,vaddr,protocol}
* Cretaed to be used in ip_vs_process_message() in
* Created to be used in ip_vs_process_message() in
* the backup synchronization daemon. It finds the
* destination to be bound to the received connection
* on the backup.
* Called under RCU lock, no refcnt is returned.
*/
struct ip_vs_dest *ip_vs_find_dest(struct net *net, int af,
const union nf_inet_addr *daddr,
Expand All @@ -615,8 +616,6 @@ struct ip_vs_dest *ip_vs_find_dest(struct net *net, int af,
dest = ip_vs_lookup_dest(svc, daddr, port);
if (!dest)
dest = ip_vs_lookup_dest(svc, daddr, port ^ dport);
if (dest)
ip_vs_dest_hold(dest);
ip_vs_service_put(svc);
return dest;
}
Expand Down Expand Up @@ -826,7 +825,7 @@ __ip_vs_update_dest(struct ip_vs_service *svc, struct ip_vs_dest *dest,
IP_VS_WAIT_WHILE(atomic_read(&svc->usecnt) > 0);

if (add) {
list_add(&dest->n_list, &svc->destinations);
list_add_rcu(&dest->n_list, &svc->destinations);
svc->num_dests++;
if (svc->scheduler->add_dest)
svc->scheduler->add_dest(svc, dest);
Expand Down Expand Up @@ -933,10 +932,10 @@ ip_vs_add_dest(struct ip_vs_service *svc, struct ip_vs_dest_user_kern *udest)

ip_vs_addr_copy(svc->af, &daddr, &udest->addr);

/*
* Check if the dest already exists in the list
*/
/* We use function that requires RCU lock */
rcu_read_lock();
dest = ip_vs_lookup_dest(svc, &daddr, dport);
rcu_read_unlock();

if (dest != NULL) {
IP_VS_DBG(1, "%s(): dest already exists\n", __func__);
Expand Down Expand Up @@ -997,10 +996,10 @@ ip_vs_edit_dest(struct ip_vs_service *svc, struct ip_vs_dest_user_kern *udest)

ip_vs_addr_copy(svc->af, &daddr, &udest->addr);

/*
* Lookup the destination list
*/
/* We use function that requires RCU lock */
rcu_read_lock();
dest = ip_vs_lookup_dest(svc, &daddr, dport);
rcu_read_unlock();

if (dest == NULL) {
IP_VS_DBG(1, "%s(): dest doesn't exist\n", __func__);
Expand Down Expand Up @@ -1069,7 +1068,7 @@ static void __ip_vs_unlink_dest(struct ip_vs_service *svc,
/*
* Remove it from the d-linked destination list.
*/
list_del(&dest->n_list);
list_del_rcu(&dest->n_list);
svc->num_dests--;

if (svcupd && svc->scheduler->del_dest)
Expand All @@ -1094,7 +1093,10 @@ ip_vs_del_dest(struct ip_vs_service *svc, struct ip_vs_dest_user_kern *udest)

EnterFunction(2);

/* We use function that requires RCU lock */
rcu_read_lock();
dest = ip_vs_lookup_dest(svc, &udest->addr, dport);
rcu_read_unlock();

if (dest == NULL) {
IP_VS_DBG(1, "%s(): destination not found!\n", __func__);
Expand Down Expand Up @@ -2104,7 +2106,7 @@ static int ip_vs_info_seq_show(struct seq_file *seq, void *v)
else
seq_putc(seq, '\n');

list_for_each_entry(dest, &svc->destinations, n_list) {
list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
#ifdef CONFIG_IP_VS_IPV6
if (dest->af == AF_INET6)
seq_printf(seq,
Expand Down
11 changes: 4 additions & 7 deletions net/netfilter/ipvs/ip_vs_sync.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -858,23 +858,20 @@ static void ip_vs_proc_conn(struct net *net, struct ip_vs_conn_param *param,
flags |= cp->flags & ~IP_VS_CONN_F_BACKUP_UPD_MASK;
cp->flags = flags;
spin_unlock(&cp->lock);
if (!dest) {
dest = ip_vs_try_bind_dest(cp);
if (dest)
ip_vs_dest_put(dest);
}
if (!dest)
ip_vs_try_bind_dest(cp);
} else {
/*
* Find the appropriate destination for the connection.
* If it is not found the connection will remain unbound
* but still handled.
*/
rcu_read_lock();
dest = ip_vs_find_dest(net, type, daddr, dport, param->vaddr,
param->vport, protocol, fwmark, flags);

cp = ip_vs_conn_new(param, daddr, dport, flags, dest, fwmark);
if (dest)
ip_vs_dest_put(dest);
rcu_read_unlock();
if (!cp) {
if (param->pe_data)
kfree(param->pe_data);
Expand Down

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