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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 <vyasevich@gmail.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Thomas Graf 2012-12-06 09:25:05 +00:00 committed by David S. Miller
parent 0b0fe913bf
commit 45122ca26c
4 changed files with 30 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/net/sctp/structs.h
View File

@ -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 *,

6
net/sctp/associola.c
View File

@ -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. */

14
net/sctp/proc.c
View File

@ -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();

18
net/sctp/transport.c
View File

@ -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.
*/