net: factor-out _sk_charge() helper

Move out of __inet_accept() the code dealing charging newly
accepted socket to memcg. MPTCP will soon use it to on a per
subflow basis, in different contexts.

No functional changes intended.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Geliang Tang <geliang@kernel.org>
Acked-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20251121-net-next-mptcp-memcg-backlog-imp-v1-1-1f34b6c1e0b1@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

3 files changed, 21 insertions, 16 deletions

diff --git a/include/net/sock.h b/include/net/sock.h
index a5f36ea9d46f..38d48cfe0741 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1631,6 +1631,8 @@ static inline void sk_mem_uncharge(struct sock *sk, int size)
 	sk_mem_reclaim(sk);
 }
 
+void __sk_charge(struct sock *sk, gfp_t gfp);
+
 #if IS_ENABLED(CONFIG_PROVE_LOCKING) && IS_ENABLED(CONFIG_MODULES)
 static inline void sk_owner_set(struct sock *sk, struct module *owner)
 {
diff --git a/net/core/sock.c b/net/core/sock.c
index 3b74fc71f51c..b26a6cdc9bcd 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -3448,6 +3448,24 @@ void __sk_mem_reclaim(struct sock *sk, int amount)
 }
 EXPORT_SYMBOL(__sk_mem_reclaim);
 
+void __sk_charge(struct sock *sk, gfp_t gfp)
+{
+	int amt;
+
+	gfp |= __GFP_NOFAIL;
+	if (mem_cgroup_from_sk(sk)) {
+		/* The socket has not been accepted yet, no need
+		 * to look at newsk->sk_wmem_queued.
+		 */
+		amt = sk_mem_pages(sk->sk_forward_alloc +
+				   atomic_read(&sk->sk_rmem_alloc));
+		if (amt)
+			mem_cgroup_sk_charge(sk, amt, gfp);
+	}
+
+	kmem_cache_charge(sk, gfp);
+}
+
 int sk_set_peek_off(struct sock *sk, int val)
 {
 	WRITE_ONCE(sk->sk_peek_off, val);
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index a31b94ce8968..08d811f11896 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -756,23 +756,8 @@ EXPORT_SYMBOL(inet_stream_connect);
 void __inet_accept(struct socket *sock, struct socket *newsock, struct sock *newsk)
 {
 	if (mem_cgroup_sockets_enabled) {
-		gfp_t gfp = GFP_KERNEL | __GFP_NOFAIL;
-
 		mem_cgroup_sk_alloc(newsk);
-
-		if (mem_cgroup_from_sk(newsk)) {
-			int amt;
-
-			/* The socket has not been accepted yet, no need
-			 * to look at newsk->sk_wmem_queued.
-			 */
-			amt = sk_mem_pages(newsk->sk_forward_alloc +
-					   atomic_read(&newsk->sk_rmem_alloc));
-			if (amt)
-				mem_cgroup_sk_charge(newsk, amt, gfp);
-		}
-
-		kmem_cache_charge(newsk, gfp);
+		__sk_charge(newsk, GFP_KERNEL);
 	}
 
 	sock_rps_record_flow(newsk);