On 12/06/2012 01:15 PM, Thomas Graf wrote:
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.
Cc: Vlad Yasevich <vyasevich@xxxxxxxxx>
Cc: Neil Horman <nhorman@xxxxxxxxxxxxx>
Signed-off-by: Thomas Graf <tgraf@xxxxxxx>
---
include/net/sctp/structs.h | 2 ++
net/sctp/associola.c | 4 ++--
net/sctp/proc.c | 8 ++++++--
net/sctp/transport.c | 18 +++++++++++++-----
4 files changed, 23 insertions(+), 9 deletions(-)
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 64158aa..5d6987b 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -948,6 +948,8 @@ 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 b1ef3bc..c826bb8 100644
--- a/net/sctp/associola.c
+++ b/net/sctp/associola.c
@@ -565,7 +565,7 @@ 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;
@@ -765,7 +765,7 @@ 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 ec9b0c8..36a3f9d 100644
--- a/net/sctp/proc.c
+++ b/net/sctp/proc.c
@@ -159,7 +159,8 @@ 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;
af = sctp_get_af_specific(addr->sa.sa_family);
@@ -168,6 +169,7 @@ static void sctp_seq_dump_remote_addrs(struct seq_file *seq, struct sctp_associa
}
af->seq_dump_addr(seq, addr);
}
+ rcu_read_unlock();
}
static void * sctp_eps_seq_start(struct seq_file *seq, loff_t *pos)
@@ -438,11 +440,12 @@ 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) {
/*
* The remote address (ADDR)
@@ -489,6 +492,7 @@ 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 206cf52..1295aec 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.
*/
We may want to mark transports as dead sooner. Probably right about the
time we pull them off the list. When displaying, we may want to
look at transport->dead, and skip them. It will reduce the probability
that we would be looking at a transport that's about to go away.
Otherwise, looks very nice.
-vlad
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