From 45122ca26ced7fae41049326a3797a73f961db2e Mon Sep 17 00:00:00 2001 From: Thomas Graf Date: Thu, 6 Dec 2012 09:25:05 +0000 Subject: [PATCH] sctp: Add RCU protection to assoc->transport_addr_list peer.transport_addr_list is currently only protected by sk_sock which is inpractical to acquire for procfs dumping purposes. This patch adds RCU protection allowing for the procfs readers to enter RCU read-side critical sections. Modification of the list continues to be serialized via sk_lock. V2: Use list_del_rcu() in sctp_association_free() to be safe Skip transports marked dead when dumping for procfs Cc: Vlad Yasevich Cc: Neil Horman Signed-off-by: Thomas Graf Acked-by: Vlad Yasevich Acked-by: Neil Horman Signed-off-by: David S. Miller --- include/net/sctp/structs.h | 2 ++ net/sctp/associola.c | 6 +++--- net/sctp/proc.c | 14 ++++++++++++-- net/sctp/transport.c | 18 +++++++++++++----- 4 files changed, 30 insertions(+), 10 deletions(-) diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h index c2521016d646..fdeb85a970fc 100644 --- a/include/net/sctp/structs.h +++ b/include/net/sctp/structs.h @@ -949,6 +949,8 @@ struct sctp_transport { /* 64-bit random number sent with heartbeat. */ __u64 hb_nonce; + + struct rcu_head rcu; }; struct sctp_transport *sctp_transport_new(struct net *, const union sctp_addr *, diff --git a/net/sctp/associola.c b/net/sctp/associola.c index ba3f9cc4c047..b45ed1f96921 100644 --- a/net/sctp/associola.c +++ b/net/sctp/associola.c @@ -448,7 +448,7 @@ void sctp_association_free(struct sctp_association *asoc) /* Release the transport structures. */ list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) { transport = list_entry(pos, struct sctp_transport, transports); - list_del(pos); + list_del_rcu(pos); sctp_transport_free(transport); } @@ -568,7 +568,7 @@ void sctp_assoc_rm_peer(struct sctp_association *asoc, sctp_assoc_update_retran_path(asoc); /* Remove this peer from the list. */ - list_del(&peer->transports); + list_del_rcu(&peer->transports); /* Get the first transport of asoc. */ pos = asoc->peer.transport_addr_list.next; @@ -769,7 +769,7 @@ struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc, peer->state = peer_state; /* Attach the remote transport to our asoc. */ - list_add_tail(&peer->transports, &asoc->peer.transport_addr_list); + list_add_tail_rcu(&peer->transports, &asoc->peer.transport_addr_list); asoc->peer.transport_count++; /* If we do not yet have a primary path, set one. */ diff --git a/net/sctp/proc.c b/net/sctp/proc.c index 06b05ee17d8d..8c19e97262ca 100644 --- a/net/sctp/proc.c +++ b/net/sctp/proc.c @@ -162,15 +162,20 @@ static void sctp_seq_dump_remote_addrs(struct seq_file *seq, struct sctp_associa struct sctp_af *af; primary = &assoc->peer.primary_addr; - list_for_each_entry(transport, &assoc->peer.transport_addr_list, + rcu_read_lock(); + list_for_each_entry_rcu(transport, &assoc->peer.transport_addr_list, transports) { addr = &transport->ipaddr; + if (transport->dead) + continue; + af = sctp_get_af_specific(addr->sa.sa_family); if (af->cmp_addr(addr, primary)) { seq_printf(seq, "*"); } af->seq_dump_addr(seq, addr); } + rcu_read_unlock(); } static void * sctp_eps_seq_start(struct seq_file *seq, loff_t *pos) @@ -441,12 +446,16 @@ static int sctp_remaddr_seq_show(struct seq_file *seq, void *v) head = &sctp_assoc_hashtable[hash]; sctp_local_bh_disable(); read_lock(&head->lock); + rcu_read_lock(); sctp_for_each_hentry(epb, node, &head->chain) { if (!net_eq(sock_net(epb->sk), seq_file_net(seq))) continue; assoc = sctp_assoc(epb); - list_for_each_entry(tsp, &assoc->peer.transport_addr_list, + list_for_each_entry_rcu(tsp, &assoc->peer.transport_addr_list, transports) { + if (tsp->dead) + continue; + /* * The remote address (ADDR) */ @@ -492,6 +501,7 @@ static int sctp_remaddr_seq_show(struct seq_file *seq, void *v) } } + rcu_read_unlock(); read_unlock(&head->lock); sctp_local_bh_enable(); diff --git a/net/sctp/transport.c b/net/sctp/transport.c index 310f11eb2206..4e45bb68aef0 100644 --- a/net/sctp/transport.c +++ b/net/sctp/transport.c @@ -163,13 +163,11 @@ void sctp_transport_free(struct sctp_transport *transport) sctp_transport_put(transport); } -/* Destroy the transport data structure. - * Assumes there are no more users of this structure. - */ -static void sctp_transport_destroy(struct sctp_transport *transport) +static void sctp_transport_destroy_rcu(struct rcu_head *head) { - SCTP_ASSERT(transport->dead, "Transport is not dead", return); + struct sctp_transport *transport; + transport = container_of(head, struct sctp_transport, rcu); if (transport->asoc) sctp_association_put(transport->asoc); @@ -180,6 +178,16 @@ static void sctp_transport_destroy(struct sctp_transport *transport) SCTP_DBG_OBJCNT_DEC(transport); } +/* Destroy the transport data structure. + * Assumes there are no more users of this structure. + */ +static void sctp_transport_destroy(struct sctp_transport *transport) +{ + SCTP_ASSERT(transport->dead, "Transport is not dead", return); + + call_rcu(&transport->rcu, sctp_transport_destroy_rcu); +} + /* Start T3_rtx timer if it is not already running and update the heartbeat * timer. This routine is called every time a DATA chunk is sent. */