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Date: Fri, 20 May 2022 17:46:00 +0100
From: David Howells <dhowells@...hat.com>
To: netdev@...r.kernel.org
Cc: dhowells@...hat.com, linux-afs@...ts.infradead.org,
linux-kernel@...r.kernel.org
Subject: [PATCH net-next 1/7] rxrpc: Allow list of in-use local UDP endpoints
to be viewed in /proc
Allow the list of in-use local UDP endpoints in the current network
namespace to be viewed in /proc.
To aid with this, the endpoint list is converted to an hlist and RCU-safe
manipulation is used so that the list can be read with only the RCU
read lock held.
Signed-off-by: David Howells <dhowells@...hat.com>
cc: Marc Dionne <marc.dionne@...istor.com>
cc: linux-afs@...ts.infradead.org
---
net/rxrpc/ar-internal.h | 5 ++-
net/rxrpc/local_object.c | 37 ++++++++++++-------------
net/rxrpc/net_ns.c | 5 +++
net/rxrpc/proc.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 94 insertions(+), 22 deletions(-)
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 969e532f77a9..ac1f88a0e120 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -88,7 +88,7 @@ struct rxrpc_net {
struct work_struct client_conn_reaper;
struct timer_list client_conn_reap_timer;
- struct list_head local_endpoints;
+ struct hlist_head local_endpoints;
struct mutex local_mutex; /* Lock for ->local_endpoints */
DECLARE_HASHTABLE (peer_hash, 10);
@@ -281,7 +281,7 @@ struct rxrpc_local {
atomic_t active_users; /* Number of users of the local endpoint */
atomic_t usage; /* Number of references to the structure */
struct rxrpc_net *rxnet; /* The network ns in which this resides */
- struct list_head link;
+ struct hlist_node link;
struct socket *socket; /* my UDP socket */
struct work_struct processor;
struct rxrpc_sock __rcu *service; /* Service(s) listening on this endpoint */
@@ -1014,6 +1014,7 @@ void rxrpc_put_peer_locked(struct rxrpc_peer *);
extern const struct seq_operations rxrpc_call_seq_ops;
extern const struct seq_operations rxrpc_connection_seq_ops;
extern const struct seq_operations rxrpc_peer_seq_ops;
+extern const struct seq_operations rxrpc_local_seq_ops;
/*
* recvmsg.c
diff --git a/net/rxrpc/local_object.c b/net/rxrpc/local_object.c
index 6a1611b0e303..ea6f338bd131 100644
--- a/net/rxrpc/local_object.c
+++ b/net/rxrpc/local_object.c
@@ -82,7 +82,7 @@ static struct rxrpc_local *rxrpc_alloc_local(struct rxrpc_net *rxnet,
atomic_set(&local->usage, 1);
atomic_set(&local->active_users, 1);
local->rxnet = rxnet;
- INIT_LIST_HEAD(&local->link);
+ INIT_HLIST_NODE(&local->link);
INIT_WORK(&local->processor, rxrpc_local_processor);
init_rwsem(&local->defrag_sem);
skb_queue_head_init(&local->reject_queue);
@@ -180,7 +180,7 @@ struct rxrpc_local *rxrpc_lookup_local(struct net *net,
{
struct rxrpc_local *local;
struct rxrpc_net *rxnet = rxrpc_net(net);
- struct list_head *cursor;
+ struct hlist_node *cursor;
const char *age;
long diff;
int ret;
@@ -190,16 +190,12 @@ struct rxrpc_local *rxrpc_lookup_local(struct net *net,
mutex_lock(&rxnet->local_mutex);
- for (cursor = rxnet->local_endpoints.next;
- cursor != &rxnet->local_endpoints;
- cursor = cursor->next) {
- local = list_entry(cursor, struct rxrpc_local, link);
+ hlist_for_each(cursor, &rxnet->local_endpoints) {
+ local = hlist_entry(cursor, struct rxrpc_local, link);
diff = rxrpc_local_cmp_key(local, srx);
- if (diff < 0)
+ if (diff != 0)
continue;
- if (diff > 0)
- break;
/* Services aren't allowed to share transport sockets, so
* reject that here. It is possible that the object is dying -
@@ -211,9 +207,10 @@ struct rxrpc_local *rxrpc_lookup_local(struct net *net,
goto addr_in_use;
}
- /* Found a match. We replace a dying object. Attempting to
- * bind the transport socket may still fail if we're attempting
- * to use a local address that the dying object is still using.
+ /* Found a match. We want to replace a dying object.
+ * Attempting to bind the transport socket may still fail if
+ * we're attempting to use a local address that the dying
+ * object is still using.
*/
if (!rxrpc_use_local(local))
break;
@@ -230,10 +227,12 @@ struct rxrpc_local *rxrpc_lookup_local(struct net *net,
if (ret < 0)
goto sock_error;
- if (cursor != &rxnet->local_endpoints)
- list_replace_init(cursor, &local->link);
- else
- list_add_tail(&local->link, cursor);
+ if (cursor) {
+ hlist_replace_rcu(cursor, &local->link);
+ cursor->pprev = NULL;
+ } else {
+ hlist_add_head_rcu(&local->link, &rxnet->local_endpoints);
+ }
age = "new";
found:
@@ -374,7 +373,7 @@ static void rxrpc_local_destroyer(struct rxrpc_local *local)
local->dead = true;
mutex_lock(&rxnet->local_mutex);
- list_del_init(&local->link);
+ hlist_del_init_rcu(&local->link);
mutex_unlock(&rxnet->local_mutex);
rxrpc_clean_up_local_conns(local);
@@ -458,9 +457,9 @@ void rxrpc_destroy_all_locals(struct rxrpc_net *rxnet)
flush_workqueue(rxrpc_workqueue);
- if (!list_empty(&rxnet->local_endpoints)) {
+ if (!hlist_empty(&rxnet->local_endpoints)) {
mutex_lock(&rxnet->local_mutex);
- list_for_each_entry(local, &rxnet->local_endpoints, link) {
+ hlist_for_each_entry(local, &rxnet->local_endpoints, link) {
pr_err("AF_RXRPC: Leaked local %p {%d}\n",
local, atomic_read(&local->usage));
}
diff --git a/net/rxrpc/net_ns.c b/net/rxrpc/net_ns.c
index cc7e30733feb..34f389975a7d 100644
--- a/net/rxrpc/net_ns.c
+++ b/net/rxrpc/net_ns.c
@@ -72,7 +72,7 @@ static __net_init int rxrpc_init_net(struct net *net)
timer_setup(&rxnet->client_conn_reap_timer,
rxrpc_client_conn_reap_timeout, 0);
- INIT_LIST_HEAD(&rxnet->local_endpoints);
+ INIT_HLIST_HEAD(&rxnet->local_endpoints);
mutex_init(&rxnet->local_mutex);
hash_init(rxnet->peer_hash);
@@ -98,6 +98,9 @@ static __net_init int rxrpc_init_net(struct net *net)
proc_create_net("peers", 0444, rxnet->proc_net,
&rxrpc_peer_seq_ops,
sizeof(struct seq_net_private));
+ proc_create_net("locals", 0444, rxnet->proc_net,
+ &rxrpc_local_seq_ops,
+ sizeof(struct seq_net_private));
return 0;
err_proc:
diff --git a/net/rxrpc/proc.c b/net/rxrpc/proc.c
index e2f990754f88..8a8f776f91ae 100644
--- a/net/rxrpc/proc.c
+++ b/net/rxrpc/proc.c
@@ -334,3 +334,72 @@ const struct seq_operations rxrpc_peer_seq_ops = {
.stop = rxrpc_peer_seq_stop,
.show = rxrpc_peer_seq_show,
};
+
+/*
+ * Generate a list of extant virtual local endpoints in /proc/net/rxrpc/locals
+ */
+static int rxrpc_local_seq_show(struct seq_file *seq, void *v)
+{
+ struct rxrpc_local *local;
+ char lbuff[50];
+
+ if (v == SEQ_START_TOKEN) {
+ seq_puts(seq,
+ "Proto Local "
+ " Use Act\n");
+ return 0;
+ }
+
+ local = hlist_entry(v, struct rxrpc_local, link);
+
+ sprintf(lbuff, "%pISpc", &local->srx.transport);
+
+ seq_printf(seq,
+ "UDP %-47.47s %3u %3u\n",
+ lbuff,
+ atomic_read(&local->usage),
+ atomic_read(&local->active_users));
+
+ return 0;
+}
+
+static void *rxrpc_local_seq_start(struct seq_file *seq, loff_t *_pos)
+ __acquires(rcu)
+{
+ struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+ unsigned int n;
+
+ rcu_read_lock();
+
+ if (*_pos >= UINT_MAX)
+ return NULL;
+
+ n = *_pos;
+ if (n == 0)
+ return SEQ_START_TOKEN;
+
+ return seq_hlist_start_rcu(&rxnet->local_endpoints, n - 1);
+}
+
+static void *rxrpc_local_seq_next(struct seq_file *seq, void *v, loff_t *_pos)
+{
+ struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+
+ if (*_pos >= UINT_MAX)
+ return NULL;
+
+ return seq_hlist_next_rcu(v, &rxnet->local_endpoints, _pos);
+}
+
+static void rxrpc_local_seq_stop(struct seq_file *seq, void *v)
+ __releases(rcu)
+{
+ rcu_read_unlock();
+}
+
+const struct seq_operations rxrpc_local_seq_ops = {
+ .start = rxrpc_local_seq_start,
+ .next = rxrpc_local_seq_next,
+ .stop = rxrpc_local_seq_stop,
+ .show = rxrpc_local_seq_show,
+};
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