write in 30M

hc

2024-02-20 ea08eeccae9297f7aabd2ef7f0c2517ac4549acc

 kernel/net/ipv4/tcp_cong.c
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@@ -1,3 +1,4 @@
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+// SPDX-License-Identifier: GPL-2.0-only
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 /*
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  * Pluggable TCP congestion control support and newReno
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  * congestion control.
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@@ -20,7 +21,7 @@
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 static LIST_HEAD(tcp_cong_list);
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 /* Simple linear search, don't expect many entries! */
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-static struct tcp_congestion_ops *tcp_ca_find(const char *name)
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+struct tcp_congestion_ops *tcp_ca_find(const char *name)
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 {
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 	struct tcp_congestion_ops *e;
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@@ -161,7 +162,7 @@
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 	rcu_read_lock();
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 	ca = rcu_dereference(net->ipv4.tcp_congestion_control);
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-	if (unlikely(!try_module_get(ca->owner)))
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+	if (unlikely(!bpf_try_module_get(ca, ca->owner)))
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 		ca = &tcp_reno;
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 	icsk->icsk_ca_ops = ca;
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 	rcu_read_unlock();
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@@ -175,7 +176,7 @@
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 void tcp_init_congestion_control(struct sock *sk)
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 {
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-	const struct inet_connection_sock *icsk = inet_csk(sk);
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+	struct inet_connection_sock *icsk = inet_csk(sk);
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 	tcp_sk(sk)->prior_ssthresh = 0;
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 	if (icsk->icsk_ca_ops->init)
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@@ -184,6 +185,7 @@
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 		INET_ECN_xmit(sk);
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 	else
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 		INET_ECN_dontxmit(sk);
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+	icsk->icsk_ca_initialized = 1;
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 }
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 static void tcp_reinit_congestion_control(struct sock *sk,
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@@ -212,7 +214,7 @@
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 	if (icsk->icsk_ca_ops->release)
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 		icsk->icsk_ca_ops->release(sk);
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-	module_put(icsk->icsk_ca_ops->owner);
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+	bpf_module_put(icsk->icsk_ca_ops, icsk->icsk_ca_ops->owner);
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 }
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 /* Used by sysctl to change default congestion control */
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@@ -226,7 +228,7 @@
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 	ca = tcp_ca_find_autoload(net, name);
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 	if (!ca) {
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 		ret = -ENOENT;
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-	} else if (!try_module_get(ca->owner)) {
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+	} else if (!bpf_try_module_get(ca, ca->owner)) {
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 		ret = -EBUSY;
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 	} else if (!net_eq(net, &init_net) &&
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 			!(ca->flags & TCP_CONG_NON_RESTRICTED)) {
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@@ -235,7 +237,7 @@
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 	} else {
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 		prev = xchg(&net->ipv4.tcp_congestion_control, ca);
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 		if (prev)
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-			module_put(prev->owner);
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+			bpf_module_put(prev, prev->owner);
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 		ca->flags |= TCP_CONG_NON_RESTRICTED;
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 		ret = 0;
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@@ -264,6 +266,9 @@
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 		offs += snprintf(buf + offs, maxlen - offs,
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 				 "%s%s",
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 				 offs == 0 ? "" : " ", ca->name);
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+
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+		if (WARN_ON_ONCE(offs >= maxlen))
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+			break;
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 	}
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 	rcu_read_unlock();
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 }
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@@ -293,6 +298,9 @@
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 		offs += snprintf(buf + offs, maxlen - offs,
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 				 "%s%s",
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 				 offs == 0 ? "" : " ", ca->name);
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+
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+		if (WARN_ON_ONCE(offs >= maxlen))
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+			break;
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 	}
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 	rcu_read_unlock();
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 }
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@@ -342,7 +350,7 @@
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  * already initialized.
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  */
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 int tcp_set_congestion_control(struct sock *sk, const char *name, bool load,
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-			       bool reinit, bool cap_net_admin)
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+			       bool cap_net_admin)
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 {
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 	struct inet_connection_sock *icsk = inet_csk(sk);
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 	const struct tcp_congestion_ops *ca;
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@@ -363,28 +371,14 @@
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 		goto out;
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 	}
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-	if (!ca) {
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+	if (!ca)
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 		err = -ENOENT;
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-	} else if (!load) {
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-		const struct tcp_congestion_ops *old_ca = icsk->icsk_ca_ops;
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-
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-		if (try_module_get(ca->owner)) {
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-			if (reinit) {
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-				tcp_reinit_congestion_control(sk, ca);
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-			} else {
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-				icsk->icsk_ca_ops = ca;
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-				module_put(old_ca->owner);
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-			}
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-		} else {
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-			err = -EBUSY;
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-		}
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-	} else if (!((ca->flags & TCP_CONG_NON_RESTRICTED) || cap_net_admin)) {
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+	else if (!((ca->flags & TCP_CONG_NON_RESTRICTED) || cap_net_admin))
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 		err = -EPERM;
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-	} else if (!try_module_get(ca->owner)) {
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+	else if (!bpf_try_module_get(ca, ca->owner))
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 		err = -EBUSY;
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-	} else {
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+	else
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 		tcp_reinit_congestion_control(sk, ca);
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-	}
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  out:
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 	rcu_read_unlock();
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 	return err;