net: no longer support SOCK_REFCNT_DEBUG feature

[PATCH v2 net-next] net: no longer support SOCK_REFCNT_DEBUG feature

Posted by Jason Xing 1 year, 2 months ago

From: Jason Xing <kernelxing@tencent.com>

Commit e48c414ee61f ("[INET]: Generalise the TCP sock ID lookup routines")
commented out the definition of SOCK_REFCNT_DEBUG in 2005 and later another
commit 463c84b97f24 ("[NET]: Introduce inet_connection_sock") removed it.
Since we could track all of them through bpf and kprobe related tools
and the feature could print loads of information which might not be
that helpful even under a little bit pressure, the whole feature which
has been inactive for many years is no longer supported.

Link: https://lore.kernel.org/lkml/20230211065153.54116-1-kerneljasonxing@gmail.com/
Suggested-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
v2:
1) change the title and body message.
2) remove the whole feature instead suggested by Kuniyuki Iwashima.
---
 include/net/sock.h              | 28 ----------------------------
 net/core/sock.c                 | 13 -------------
 net/ipv4/af_inet.c              |  3 ---
 net/ipv4/inet_connection_sock.c |  2 --
 net/ipv4/inet_timewait_sock.c   |  3 ---
 net/ipv6/af_inet6.c             | 10 ----------
 net/ipv6/ipv6_sockglue.c        | 12 ------------
 net/mptcp/protocol.c            |  1 -
 net/packet/af_packet.c          |  4 ----
 net/sctp/ipv6.c                 |  2 --
 net/sctp/protocol.c             |  2 --
 net/smc/af_smc.c                |  3 ---
 net/xdp/xsk.c                   |  4 ----
 13 files changed, 87 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index dcd72e6285b2..e6369068a7bb 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1349,9 +1349,6 @@ struct proto {
 	char			name[32];
 
 	struct list_head	node;
-#ifdef SOCK_REFCNT_DEBUG
-	atomic_t		socks;
-#endif
 	int			(*diag_destroy)(struct sock *sk, int err);
 } __randomize_layout;
 
@@ -1359,31 +1356,6 @@ int proto_register(struct proto *prot, int alloc_slab);
 void proto_unregister(struct proto *prot);
 int sock_load_diag_module(int family, int protocol);
 
-#ifdef SOCK_REFCNT_DEBUG
-static inline void sk_refcnt_debug_inc(struct sock *sk)
-{
-	atomic_inc(&sk->sk_prot->socks);
-}
-
-static inline void sk_refcnt_debug_dec(struct sock *sk)
-{
-	atomic_dec(&sk->sk_prot->socks);
-	printk(KERN_DEBUG "%s socket %p released, %d are still alive\n",
-	       sk->sk_prot->name, sk, atomic_read(&sk->sk_prot->socks));
-}
-
-static inline void sk_refcnt_debug_release(const struct sock *sk)
-{
-	if (refcount_read(&sk->sk_refcnt) != 1)
-		printk(KERN_DEBUG "Destruction of the %s socket %p delayed, refcnt=%d\n",
-		       sk->sk_prot->name, sk, refcount_read(&sk->sk_refcnt));
-}
-#else /* SOCK_REFCNT_DEBUG */
-#define sk_refcnt_debug_inc(sk) do { } while (0)
-#define sk_refcnt_debug_dec(sk) do { } while (0)
-#define sk_refcnt_debug_release(sk) do { } while (0)
-#endif /* SOCK_REFCNT_DEBUG */
-
 INDIRECT_CALLABLE_DECLARE(bool tcp_stream_memory_free(const struct sock *sk, int wake));
 
 static inline int sk_forward_alloc_get(const struct sock *sk)
diff --git a/net/core/sock.c b/net/core/sock.c
index f954d5893e79..be7b29d97637 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2338,17 +2338,6 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority)
 	smp_wmb();
 	refcount_set(&newsk->sk_refcnt, 2);
 
-	/* Increment the counter in the same struct proto as the master
-	 * sock (sk_refcnt_debug_inc uses newsk->sk_prot->socks, that
-	 * is the same as sk->sk_prot->socks, as this field was copied
-	 * with memcpy).
-	 *
-	 * This _changes_ the previous behaviour, where
-	 * tcp_create_openreq_child always was incrementing the
-	 * equivalent to tcp_prot->socks (inet_sock_nr), so this have
-	 * to be taken into account in all callers. -acme
-	 */
-	sk_refcnt_debug_inc(newsk);
 	sk_set_socket(newsk, NULL);
 	sk_tx_queue_clear(newsk);
 	RCU_INIT_POINTER(newsk->sk_wq, NULL);
@@ -3696,8 +3685,6 @@ void sk_common_release(struct sock *sk)
 
 	xfrm_sk_free_policy(sk);
 
-	sk_refcnt_debug_release(sk);
-
 	sock_put(sk);
 }
 EXPORT_SYMBOL(sk_common_release);
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 6c0ec2789943..f46a3924c440 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -156,7 +156,6 @@ void inet_sock_destruct(struct sock *sk)
 	kfree(rcu_dereference_protected(inet->inet_opt, 1));
 	dst_release(rcu_dereference_protected(sk->sk_dst_cache, 1));
 	dst_release(rcu_dereference_protected(sk->sk_rx_dst, 1));
-	sk_refcnt_debug_dec(sk);
 }
 EXPORT_SYMBOL(inet_sock_destruct);
 
@@ -356,8 +355,6 @@ static int inet_create(struct net *net, struct socket *sock, int protocol,
 	inet->mc_list	= NULL;
 	inet->rcv_tos	= 0;
 
-	sk_refcnt_debug_inc(sk);
-
 	if (inet->inet_num) {
 		/* It assumes that any protocol which allows
 		 * the user to assign a number at socket
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index d1f837579398..64be59d93b04 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -1178,8 +1178,6 @@ void inet_csk_destroy_sock(struct sock *sk)
 
 	xfrm_sk_free_policy(sk);
 
-	sk_refcnt_debug_release(sk);
-
 	this_cpu_dec(*sk->sk_prot->orphan_count);
 
 	sock_put(sk);
diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index beed32fff484..40052414c7c7 100644
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -77,9 +77,6 @@ void inet_twsk_free(struct inet_timewait_sock *tw)
 {
 	struct module *owner = tw->tw_prot->owner;
 	twsk_destructor((struct sock *)tw);
-#ifdef SOCK_REFCNT_DEBUG
-	pr_debug("%s timewait_sock %p released\n", tw->tw_prot->name, tw);
-#endif
 	kmem_cache_free(tw->tw_prot->twsk_prot->twsk_slab, tw);
 	module_put(owner);
 }
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index fee9163382c2..c93f2e865fea 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -238,16 +238,6 @@ static int inet6_create(struct net *net, struct socket *sock, int protocol,
 		inet->pmtudisc = IP_PMTUDISC_DONT;
 	else
 		inet->pmtudisc = IP_PMTUDISC_WANT;
-	/*
-	 * Increment only the relevant sk_prot->socks debug field, this changes
-	 * the previous behaviour of incrementing both the equivalent to
-	 * answer->prot->socks (inet6_sock_nr) and inet_sock_nr.
-	 *
-	 * This allows better debug granularity as we'll know exactly how many
-	 * UDPv6, TCPv6, etc socks were allocated, not the sum of all IPv6
-	 * transport protocol socks. -acme
-	 */
-	sk_refcnt_debug_inc(sk);
 
 	if (inet->inet_num) {
 		/* It assumes that any protocol which allows
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 9ce51680290b..2917dd8d198c 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -464,13 +464,6 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 			__ipv6_sock_mc_close(sk);
 			__ipv6_sock_ac_close(sk);
 
-			/*
-			 * Sock is moving from IPv6 to IPv4 (sk_prot), so
-			 * remove it from the refcnt debug socks count in the
-			 * original family...
-			 */
-			sk_refcnt_debug_dec(sk);
-
 			if (sk->sk_protocol == IPPROTO_TCP) {
 				struct inet_connection_sock *icsk = inet_csk(sk);
 
@@ -507,11 +500,6 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 
 			inet6_cleanup_sock(sk);
 
-			/*
-			 * ... and add it to the refcnt debug socks count
-			 * in the new family. -acme
-			 */
-			sk_refcnt_debug_inc(sk);
 			module_put(THIS_MODULE);
 			retv = 0;
 			break;
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 8cd6cc67c2c5..e913752df112 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2876,7 +2876,6 @@ static void __mptcp_destroy_sock(struct sock *sk)
 	sk_stream_kill_queues(sk);
 	xfrm_sk_free_policy(sk);
 
-	sk_refcnt_debug_release(sk);
 	sock_put(sk);
 }
 
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index b5ab98ca2511..a4c8f86ac12a 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1335,8 +1335,6 @@ static void packet_sock_destruct(struct sock *sk)
 		pr_err("Attempt to release alive packet socket: %p\n", sk);
 		return;
 	}
-
-	sk_refcnt_debug_dec(sk);
 }
 
 static bool fanout_flow_is_huge(struct packet_sock *po, struct sk_buff *skb)
@@ -3172,7 +3170,6 @@ static int packet_release(struct socket *sock)
 
 	skb_queue_purge(&sk->sk_receive_queue);
 	packet_free_pending(po);
-	sk_refcnt_debug_release(sk);
 
 	sock_put(sk);
 	return 0;
@@ -3362,7 +3359,6 @@ static int packet_create(struct net *net, struct socket *sock, int protocol,
 	packet_cached_dev_reset(po);
 
 	sk->sk_destruct = packet_sock_destruct;
-	sk_refcnt_debug_inc(sk);
 
 	/*
 	 *	Attach a protocol block
diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
index 097bd60ce964..62b436a2c8fe 100644
--- a/net/sctp/ipv6.c
+++ b/net/sctp/ipv6.c
@@ -807,8 +807,6 @@ static struct sock *sctp_v6_create_accept_sk(struct sock *sk,
 
 	newsk->sk_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
 
-	sk_refcnt_debug_inc(newsk);
-
 	if (newsk->sk_prot->init(newsk)) {
 		sk_common_release(newsk);
 		newsk = NULL;
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index 909a89a1cff4..c365df24ad33 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -601,8 +601,6 @@ static struct sock *sctp_v4_create_accept_sk(struct sock *sk,
 
 	newinet->inet_daddr = asoc->peer.primary_addr.v4.sin_addr.s_addr;
 
-	sk_refcnt_debug_inc(newsk);
-
 	if (newsk->sk_prot->init(newsk)) {
 		sk_common_release(newsk);
 		newsk = NULL;
diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index e12d4fa5aece..c594312e22cd 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -359,8 +359,6 @@ static void smc_destruct(struct sock *sk)
 		return;
 	if (!sock_flag(sk, SOCK_DEAD))
 		return;
-
-	sk_refcnt_debug_dec(sk);
 }
 
 static struct sock *smc_sock_alloc(struct net *net, struct socket *sock,
@@ -389,7 +387,6 @@ static struct sock *smc_sock_alloc(struct net *net, struct socket *sock,
 	spin_lock_init(&smc->accept_q_lock);
 	spin_lock_init(&smc->conn.send_lock);
 	sk->sk_prot->hash(sk);
-	sk_refcnt_debug_inc(sk);
 	mutex_init(&smc->clcsock_release_lock);
 	smc_init_saved_callbacks(smc);
 
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 9f0561b67c12..a245c1b4a21b 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -845,7 +845,6 @@ static int xsk_release(struct socket *sock)
 	sock_orphan(sk);
 	sock->sk = NULL;
 
-	sk_refcnt_debug_release(sk);
 	sock_put(sk);
 
 	return 0;
@@ -1396,8 +1395,6 @@ static void xsk_destruct(struct sock *sk)
 
 	if (!xp_put_pool(xs->pool))
 		xdp_put_umem(xs->umem, !xs->pool);
-
-	sk_refcnt_debug_dec(sk);
 }
 
 static int xsk_create(struct net *net, struct socket *sock, int protocol,
@@ -1427,7 +1424,6 @@ static int xsk_create(struct net *net, struct socket *sock, int protocol,
 	sk->sk_family = PF_XDP;
 
 	sk->sk_destruct = xsk_destruct;
-	sk_refcnt_debug_inc(sk);
 
 	sock_set_flag(sk, SOCK_RCU_FREE);
 
-- 
2.37.3

Re: net: no longer support SOCK_REFCNT_DEBUG feature: Tests Results

Posted by MPTCP CI 1 year, 2 months ago

Hi Jason,

Thank you for your modifications, that's great!

Our CI did some validations and here is its report:

- KVM Validation: normal (except selftest_mptcp_join):
  - Success! ✅:
  - Task: https://cirrus-ci.com/task/5794989825851392
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/5794989825851392/summary/summary.txt

- KVM Validation: debug (except selftest_mptcp_join):
  - Success! ✅:
  - Task: https://cirrus-ci.com/task/6357939779272704
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/6357939779272704/summary/summary.txt

- KVM Validation: debug (only selftest_mptcp_join):
  - Success! ✅:
  - Task: https://cirrus-ci.com/task/4950564895719424
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/4950564895719424/summary/summary.txt

- KVM Validation: normal (only selftest_mptcp_join):
  - Success! ✅:
  - Task: https://cirrus-ci.com/task/5232039872430080
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/5232039872430080/summary/summary.txt

Initiator: Patchew Applier
Commits: https://github.com/multipath-tcp/mptcp_net-next/commits/f52d07972da8


If there are some issues, you can reproduce them using the same environment as
the one used by the CI thanks to a docker image, e.g.:

    $ cd [kernel source code]
    $ docker run -v "${PWD}:${PWD}:rw" -w "${PWD}" --privileged --rm -it \
        --pull always mptcp/mptcp-upstream-virtme-docker:latest \
        auto-debug

For more details:

    https://github.com/multipath-tcp/mptcp-upstream-virtme-docker


Please note that despite all the efforts that have been already done to have a
stable tests suite when executed on a public CI like here, it is possible some
reported issues are not due to your modifications. Still, do not hesitate to
help us improve that ;-)

Cheers,
MPTCP GH Action bot
Bot operated by Matthieu Baerts (Tessares)