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l2tp: replace hlist with simple list for per-tunnel session list

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The per-tunnel session list is no longer used by the
datapath. However, we still need a list of sessions in the tunnel for
l2tp_session_get_nth, which is used by management code. (An
alternative might be to walk each session IDR list, matching only
sessions of a given tunnel.)

Replace the per-tunnel hlist with a per-tunnel list. In functions
which walk a list of sessions of a tunnel, walk this list instead.

Signed-off-by: James Chapman <jchapman@katalix.com>
Reviewed-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
James Chapman 2024-06-20 12:22:44 +01:00 committed by David S. Miller
parent 8c6245af4f
commit d18d3f0a24
3 changed files with 49 additions and 90 deletions
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107
net/l2tp/l2tp_core.c
View File

@ -39,7 +39,6 @@
#include <linux/ip.h>
#include <linux/udp.h>
#include <linux/l2tp.h>
#include <linux/hash.h>
#include <linux/sort.h>
#include <linux/file.h>
#include <linux/nsproxy.h>
@ -137,18 +136,6 @@ static inline struct l2tp_net *l2tp_pernet(const struct net *net)
return net_generic(net, l2tp_net_id);
}
/* Session hash list.
* The session_id SHOULD be random according to RFC2661, but several
* L2TP implementations (Cisco and Microsoft) use incrementing
* session_ids. So we do a real hash on the session_id, rather than a
* simple bitmask.
*/
static inline struct hlist_head *
l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
{
return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
}
static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
{
trace_free_tunnel(tunnel);
@ -306,21 +293,17 @@ EXPORT_SYMBOL_GPL(l2tp_session_get);
struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth)
{
int hash;
struct l2tp_session *session;
int count = 0;
rcu_read_lock_bh();
for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
hlist_for_each_entry_rcu(session, &tunnel->session_hlist[hash], hlist) {
if (++count > nth) {
l2tp_session_inc_refcount(session);
rcu_read_unlock_bh();
return session;
}
list_for_each_entry_rcu(session, &tunnel->session_list, list) {
if (++count > nth) {
l2tp_session_inc_refcount(session);
rcu_read_unlock_bh();
return session;
}
}
rcu_read_unlock_bh();
return NULL;
@ -334,21 +317,23 @@ struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
const char *ifname)
{
struct l2tp_net *pn = l2tp_pernet(net);
unsigned long session_id, tmp;
unsigned long tunnel_id, tmp;
struct l2tp_session *session;
struct l2tp_tunnel *tunnel;
rcu_read_lock_bh();
idr_for_each_entry_ul(&pn->l2tp_v3_session_idr, session, tmp, session_id) {
if (session) {
if (!strcmp(session->ifname, ifname)) {
l2tp_session_inc_refcount(session);
rcu_read_unlock_bh();
idr_for_each_entry_ul(&pn->l2tp_tunnel_idr, tunnel, tmp, tunnel_id) {
if (tunnel) {
list_for_each_entry_rcu(session, &tunnel->session_list, list) {
if (!strcmp(session->ifname, ifname)) {
l2tp_session_inc_refcount(session);
rcu_read_unlock_bh();
return session;
return session;
}
}
}
}
rcu_read_unlock_bh();
return NULL;
@ -452,25 +437,15 @@ int l2tp_session_register(struct l2tp_session *session,
struct l2tp_tunnel *tunnel)
{
struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
struct l2tp_session *session_walk;
struct hlist_head *head;
u32 session_key;
int err;
head = l2tp_session_id_hash(tunnel, session->session_id);
spin_lock_bh(&tunnel->hlist_lock);
spin_lock_bh(&tunnel->list_lock);
if (!tunnel->acpt_newsess) {
err = -ENODEV;
goto err_tlock;
}
hlist_for_each_entry(session_walk, head, hlist)
if (session_walk->session_id == session->session_id) {
err = -EEXIST;
goto err_tlock;
}
if (tunnel->version == L2TP_HDR_VER_3) {
session_key = session->session_id;
spin_lock_bh(&pn->l2tp_session_idr_lock);
@ -506,8 +481,8 @@ int l2tp_session_register(struct l2tp_session *session,
l2tp_tunnel_inc_refcount(tunnel);
hlist_add_head_rcu(&session->hlist, head);
spin_unlock_bh(&tunnel->hlist_lock);
list_add(&session->list, &tunnel->session_list);
spin_unlock_bh(&tunnel->list_lock);
spin_lock_bh(&pn->l2tp_session_idr_lock);
if (tunnel->version == L2TP_HDR_VER_3)
@ -521,7 +496,7 @@ int l2tp_session_register(struct l2tp_session *session,
return 0;
err_tlock:
spin_unlock_bh(&tunnel->hlist_lock);
spin_unlock_bh(&tunnel->list_lock);
return err;
}
@ -1275,20 +1250,19 @@ end:
return;
}
/* Remove an l2tp session from l2tp_core's hash lists. */
/* Remove an l2tp session from l2tp_core's lists. */
static void l2tp_session_unhash(struct l2tp_session *session)
{
struct l2tp_tunnel *tunnel = session->tunnel;
/* Remove the session from core hashes */
if (tunnel) {
struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
struct l2tp_session *removed = session;
/* Remove from the per-tunnel hash */
spin_lock_bh(&tunnel->hlist_lock);
hlist_del_init_rcu(&session->hlist);
spin_unlock_bh(&tunnel->hlist_lock);
/* Remove from the per-tunnel list */
spin_lock_bh(&tunnel->list_lock);
list_del_init(&session->list);
spin_unlock_bh(&tunnel->list_lock);
/* Remove from per-net IDR */
spin_lock_bh(&pn->l2tp_session_idr_lock);
@ -1316,28 +1290,19 @@ static void l2tp_session_unhash(struct l2tp_session *session)
static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
{
struct l2tp_session *session;
int hash;
struct list_head __rcu *pos;
struct list_head *tmp;
spin_lock_bh(&tunnel->hlist_lock);
spin_lock_bh(&tunnel->list_lock);
tunnel->acpt_newsess = false;
for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
again:
hlist_for_each_entry_rcu(session, &tunnel->session_hlist[hash], hlist) {
hlist_del_init_rcu(&session->hlist);
spin_unlock_bh(&tunnel->hlist_lock);
l2tp_session_delete(session);
spin_lock_bh(&tunnel->hlist_lock);
/* Now restart from the beginning of this hash
* chain. We always remove a session from the
* list so we are guaranteed to make forward
* progress.
*/
goto again;
}
list_for_each_safe(pos, tmp, &tunnel->session_list) {
session = list_entry(pos, struct l2tp_session, list);
list_del_init(&session->list);
spin_unlock_bh(&tunnel->list_lock);
l2tp_session_delete(session);
spin_lock_bh(&tunnel->list_lock);
}
spin_unlock_bh(&tunnel->hlist_lock);
spin_unlock_bh(&tunnel->list_lock);
}
/* Tunnel socket destroy hook for UDP encapsulation */
@ -1531,8 +1496,9 @@ int l2tp_tunnel_create(int fd, int version, u32 tunnel_id, u32 peer_tunnel_id,
tunnel->magic = L2TP_TUNNEL_MAGIC;
sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
spin_lock_init(&tunnel->hlist_lock);
spin_lock_init(&tunnel->list_lock);
tunnel->acpt_newsess = true;
INIT_LIST_HEAD(&tunnel->session_list);
tunnel->encap = encap;
@ -1732,6 +1698,7 @@ struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunn
session->hlist_key = l2tp_v3_session_hashkey(tunnel->sock, session->session_id);
INIT_HLIST_NODE(&session->hlist);
INIT_LIST_HEAD(&session->clist);
INIT_LIST_HEAD(&session->list);
if (cfg) {
session->pwtype = cfg->pw_type;

19
net/l2tp/l2tp_core.h
View File

@ -19,10 +19,6 @@
#define L2TP_TUNNEL_MAGIC 0x42114DDA
#define L2TP_SESSION_MAGIC 0x0C04EB7D
/* Per tunnel session hash table size */
#define L2TP_HASH_BITS 4
#define L2TP_HASH_SIZE BIT(L2TP_HASH_BITS)
struct sk_buff;
struct l2tp_stats {
@ -65,8 +61,7 @@ struct l2tp_session_coll_list {
/* Represents a session (pseudowire) instance.
* Tracks runtime state including cookies, dataplane packet sequencing, and IO statistics.
* Is linked into a per-tunnel session hashlist; and in the case of an L2TPv3 session into
* an additional per-net ("global") hashlist.
* Is linked into a per-tunnel session list and a per-net ("global") IDR tree.
*/
#define L2TP_SESSION_NAME_MAX 32
struct l2tp_session {
@ -90,6 +85,7 @@ struct l2tp_session {
u32 nr_oos; /* NR of last OOS packet */
int nr_oos_count; /* for OOS recovery */
int nr_oos_count_max;
struct list_head list; /* per-tunnel list node */
refcount_t ref_count;
struct hlist_node hlist; /* per-net session hlist */
unsigned long hlist_key; /* key for session hlist */
@ -118,7 +114,7 @@ struct l2tp_session {
/* Session close handler.
* Each pseudowire implementation may implement this callback in order to carry
* out pseudowire-specific shutdown actions.
* The callback is called by core after unhashing the session and purging its
* The callback is called by core after unlisting the session and purging its
* reorder queue.
*/
void (*session_close)(struct l2tp_session *session);
@ -154,7 +150,7 @@ struct l2tp_tunnel_cfg {
/* Represents a tunnel instance.
* Tracks runtime state including IO statistics.
* Holds the tunnel socket (either passed from userspace or directly created by the kernel).
* Maintains a hashlist of sessions belonging to the tunnel instance.
* Maintains a list of sessions belonging to the tunnel instance.
* Is linked into a per-net list of tunnels.
*/
#define L2TP_TUNNEL_NAME_MAX 20
@ -164,12 +160,11 @@ struct l2tp_tunnel {
unsigned long dead;
struct rcu_head rcu;
spinlock_t hlist_lock; /* write-protection for session_hlist */
spinlock_t list_lock; /* write-protection for session_list */
bool acpt_newsess; /* indicates whether this tunnel accepts
* new sessions. Protected by hlist_lock.
* new sessions. Protected by list_lock.
*/
struct hlist_head session_hlist[L2TP_HASH_SIZE];
/* hashed list of sessions, hashed by id */
struct list_head session_list; /* list of sessions */
u32 tunnel_id;
u32 peer_tunnel_id;
int version; /* 2=>L2TPv2, 3=>L2TPv3 */

13
net/l2tp/l2tp_debugfs.c
View File

@ -123,17 +123,14 @@ static void l2tp_dfs_seq_tunnel_show(struct seq_file *m, void *v)
struct l2tp_tunnel *tunnel = v;
struct l2tp_session *session;
int session_count = 0;
int hash;
rcu_read_lock_bh();
for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
hlist_for_each_entry_rcu(session, &tunnel->session_hlist[hash], hlist) {
/* Session ID of zero is a dummy/reserved value used by pppol2tp */
if (session->session_id == 0)
continue;
list_for_each_entry_rcu(session, &tunnel->session_list, list) {
/* Session ID of zero is a dummy/reserved value used by pppol2tp */
if (session->session_id == 0)
continue;
session_count++;
}
session_count++;
}
rcu_read_unlock_bh();