On Tue, Nov 15, 2016 at 11:23:11PM +0800, Xin Long wrote:
> Now sctp transport rhashtable uses hash(lport, dport, daddr) as the key
> to hash a node to one chain. If in one host thousands of assocs connect
> to one server with the same lport and different laddrs (although it's
> not a normal case), all the transports would be hashed into the same
> chain.
>
> It may cause to keep returning -EBUSY when inserting a new node, as the
> chain is too long and sctp inserts a transport node in a loop, which
> could even lead to system hangs there.
>
> The new rhlist interface works for this case that there are many nodes
> with the same key in one chain. It puts them into a list then makes this
> list be as a node of the chain.
>
> This patch is to replace rhashtable_ interface with rhltable_ interface.
> Since a chain would not be too long and it would not return -EBUSY with
> this fix when inserting a node, the reinsert loop is also removed here.
>
> Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>
> ---
> include/net/sctp/sctp.h | 2 +-
> include/net/sctp/structs.h | 4 +-
> net/sctp/associola.c | 8 +++-
> net/sctp/input.c | 93 ++++++++++++++++++++++++++--------------------
> net/sctp/socket.c | 7 +---
> 5 files changed, 64 insertions(+), 50 deletions(-)
>
> diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
> index 31acc3f..f0dcaeb 100644
> --- a/include/net/sctp/sctp.h
> +++ b/include/net/sctp/sctp.h
> @@ -164,7 +164,7 @@ void sctp_backlog_migrate(struct sctp_association *assoc,
> struct sock *oldsk, struct sock *newsk);
> int sctp_transport_hashtable_init(void);
> void sctp_transport_hashtable_destroy(void);
> -void sctp_hash_transport(struct sctp_transport *t);
> +int sctp_hash_transport(struct sctp_transport *t);
> void sctp_unhash_transport(struct sctp_transport *t);
> struct sctp_transport *sctp_addrs_lookup_transport(
> struct net *net,
> diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
> index 11c3bf2..c5a2d83 100644
> --- a/include/net/sctp/structs.h
> +++ b/include/net/sctp/structs.h
> @@ -124,7 +124,7 @@ extern struct sctp_globals {
> /* This is the sctp port control hash. */
> struct sctp_bind_hashbucket *port_hashtable;
> /* This is the hash of all transports. */
> - struct rhashtable transport_hashtable;
> + struct rhltable transport_hashtable;
>
> /* Sizes of above hashtables. */
> int ep_hashsize;
> @@ -762,7 +762,7 @@ static inline int sctp_packet_empty(struct sctp_packet *packet)
> struct sctp_transport {
> /* A list of transports. */
> struct list_head transports;
> - struct rhash_head node;
> + struct rhlist_head node;
>
> /* Reference counting. */
> atomic_t refcnt;
> diff --git a/net/sctp/associola.c b/net/sctp/associola.c
> index f10d339..68428e1 100644
> --- a/net/sctp/associola.c
> +++ b/net/sctp/associola.c
> @@ -700,11 +700,15 @@ struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
> /* Set the peer's active state. */
> peer->state = peer_state;
>
> + /* Add this peer into the transport hashtable */
> + if (sctp_hash_transport(peer)) {
> + sctp_transport_free(peer);
> + return NULL;
> + }
> +
> /* Attach the remote transport to our asoc. */
> list_add_tail_rcu(&peer->transports, &asoc->peer.transport_addr_list);
> asoc->peer.transport_count++;
> - /* Add this peer into the transport hashtable */
> - sctp_hash_transport(peer);
>
> /* If we do not yet have a primary path, set one. */
> if (!asoc->peer.primary_path) {
> diff --git a/net/sctp/input.c b/net/sctp/input.c
> index a01a56e..458e506 100644
> --- a/net/sctp/input.c
> +++ b/net/sctp/input.c
> @@ -790,10 +790,9 @@ static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net,
>
> /* rhashtable for transport */
> struct sctp_hash_cmp_arg {
> - const struct sctp_endpoint *ep;
> - const union sctp_addr *laddr;
> - const union sctp_addr *paddr;
> - const struct net *net;
> + const union sctp_addr *paddr;
> + const struct net *net;
> + u16 lport;
> };
>
> static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg,
> @@ -801,7 +800,6 @@ static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg,
> {
> struct sctp_transport *t = (struct sctp_transport *)ptr;
> const struct sctp_hash_cmp_arg *x = arg->key;
> - struct sctp_association *asoc;
> int err = 1;
>
> if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr))
> @@ -809,19 +807,10 @@ static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg,
> if (!sctp_transport_hold(t))
> return err;
>
> - asoc = t->asoc;
> - if (!net_eq(sock_net(asoc->base.sk), x->net))
> + if (!net_eq(sock_net(t->asoc->base.sk), x->net))
> + goto out;
> + if (x->lport != htons(t->asoc->base.bind_addr.port))
> goto out;
> - if (x->ep) {
> - if (x->ep != asoc->ep)
> - goto out;
> - } else {
> - if (x->laddr->v4.sin_port != htons(asoc->base.bind_addr.port))
> - goto out;
> - if (!sctp_bind_addr_match(&asoc->base.bind_addr,
> - x->laddr, sctp_sk(asoc->base.sk)))
> - goto out;
> - }
>
> err = 0;
> out:
> @@ -851,11 +840,9 @@ static inline u32 sctp_hash_key(const void *data, u32 len, u32 seed)
> const struct sctp_hash_cmp_arg *x = data;
> const union sctp_addr *paddr = x->paddr;
> const struct net *net = x->net;
> - u16 lport;
> + u16 lport = x->lport;
> u32 addr;
>
> - lport = x->ep ? htons(x->ep->base.bind_addr.port) :
> - x->laddr->v4.sin_port;
> if (paddr->sa.sa_family == AF_INET6)
> addr = jhash(&paddr->v6.sin6_addr, 16, seed);
> else
> @@ -875,29 +862,32 @@ static const struct rhashtable_params sctp_hash_params = {
>
> int sctp_transport_hashtable_init(void)
> {
> - return rhashtable_init(&sctp_transport_hashtable, &sctp_hash_params);
> + return rhltable_init(&sctp_transport_hashtable, &sctp_hash_params);
> }
>
> void sctp_transport_hashtable_destroy(void)
> {
> - rhashtable_destroy(&sctp_transport_hashtable);
> + rhltable_destroy(&sctp_transport_hashtable);
> }
>
> -void sctp_hash_transport(struct sctp_transport *t)
> +int sctp_hash_transport(struct sctp_transport *t)
> {
> struct sctp_hash_cmp_arg arg;
> + int err;
>
> if (t->asoc->temp)
> - return;
> + return 0;
>
> - arg.ep = t->asoc->ep;
> - arg.paddr = &t->ipaddr;
> arg.net = sock_net(t->asoc->base.sk);
> + arg.paddr = &t->ipaddr;
> + arg.lport = htons(t->asoc->base.bind_addr.port);
>
> -reinsert:
> - if (rhashtable_lookup_insert_key(&sctp_transport_hashtable, &arg,
> - &t->node, sctp_hash_params) == -EBUSY)
> - goto reinsert;
> + err = rhltable_insert_key(&sctp_transport_hashtable, &arg,
> + &t->node, sctp_hash_params);
> + if (err)
> + pr_err_once("insert transport fail, errno %d\n", err);
> +
> + return err;
> }
>
> void sctp_unhash_transport(struct sctp_transport *t)
> @@ -905,39 +895,62 @@ void sctp_unhash_transport(struct sctp_transport *t)
> if (t->asoc->temp)
> return;
>
> - rhashtable_remove_fast(&sctp_transport_hashtable, &t->node,
> - sctp_hash_params);
> + rhltable_remove(&sctp_transport_hashtable, &t->node,
> + sctp_hash_params);
> }
>
> +/* return a transport with holding it */
> struct sctp_transport *sctp_addrs_lookup_transport(
> struct net *net,
> const union sctp_addr *laddr,
> const union sctp_addr *paddr)
> {
> + struct rhlist_head *tmp, *list;
> + struct sctp_transport *t;
> struct sctp_hash_cmp_arg arg = {
> - .ep = NULL,
> - .laddr = laddr,
> .paddr = paddr,
> .net = net,
> + .lport = laddr->v4.sin_port,
> };
>
> - return rhashtable_lookup_fast(&sctp_transport_hashtable, &arg,
> - sctp_hash_params);
> + list = rhltable_lookup(&sctp_transport_hashtable, &arg,
> + sctp_hash_params);
> +
> + rhl_for_each_entry_rcu(t, tmp, list, node) {
> + if (!sctp_transport_hold(t))
> + continue;
> +
> + if (sctp_bind_addr_match(&t->asoc->base.bind_addr,
> + laddr, sctp_sk(t->asoc->base.sk)))
> + return t;
> + sctp_transport_put(t);
> + }
> +
> + return NULL;
> }
>
> +/* return a transport without holding it, as it's only used under sock lock */
> struct sctp_transport *sctp_epaddr_lookup_transport(
> const struct sctp_endpoint *ep,
> const union sctp_addr *paddr)
> {
> struct net *net = sock_net(ep->base.sk);
> + struct rhlist_head *tmp, *list;
> + struct sctp_transport *t;
> struct sctp_hash_cmp_arg arg = {
> - .ep = ep,
> .paddr = paddr,
> .net = net,
> + .lport = htons(ep->base.bind_addr.port),
> };
>
> - return rhashtable_lookup_fast(&sctp_transport_hashtable, &arg,
> - sctp_hash_params);
> + list = rhltable_lookup(&sctp_transport_hashtable, &arg,
> + sctp_hash_params);
> +
> + rhl_for_each_entry_rcu(t, tmp, list, node)
> + if (ep == t->asoc->ep)
> + return t;
> +
> + return NULL;
> }
>
> /* Look up an association. */
> @@ -951,7 +964,7 @@ static struct sctp_association *__sctp_lookup_association(
> struct sctp_association *asoc = NULL;
>
> t = sctp_addrs_lookup_transport(net, local, peer);
> - if (!t || !sctp_transport_hold(t))
> + if (!t)
> goto out;
>
> asoc = t->asoc;
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index f23ad91..d5f4b4a 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -4392,10 +4392,7 @@ int sctp_transport_walk_start(struct rhashtable_iter *iter)
> {
> int err;
>
> - err = rhashtable_walk_init(&sctp_transport_hashtable, iter,
> - GFP_KERNEL);
> - if (err)
> - return err;
> + rhltable_walk_enter(&sctp_transport_hashtable, iter);
>
> err = rhashtable_walk_start(iter);
> if (err && err != -EAGAIN) {
> @@ -4479,7 +4476,7 @@ int sctp_transport_lookup_process(int (*cb)(struct sctp_transport *, void *),
>
> rcu_read_lock();
> transport = sctp_addrs_lookup_transport(net, laddr, paddr);
> - if (!transport || !sctp_transport_hold(transport))
> + if (!transport)
> goto out;
>
> rcu_read_unlock();
> --
> 2.1.0
>
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