1 files changed, 59 insertions, 17 deletions

diff --git a/tools/testing/selftests/bpf/progs/bpf_dctcp.c b/tools/testing/selftests/bpf/progs/bpf_dctcp.c
index b631fb5032d2..460682759aed 100644
--- a/tools/testing/selftests/bpf/progs/bpf_dctcp.c
+++ b/tools/testing/selftests/bpf/progs/bpf_dctcp.c
@@ -6,14 +6,33 @@
  * the kernel BPF logic.
  */
 
+#include <stddef.h>
 #include <linux/bpf.h>
 #include <linux/types.h>
+#include <linux/stddef.h>
+#include <linux/tcp.h>
+#include <errno.h>
 #include <bpf/bpf_helpers.h>
-#include "bpf_trace_helpers.h"
+#include <bpf/bpf_tracing.h>
 #include "bpf_tcp_helpers.h"
 
 char _license[] SEC("license") = "GPL";
 
+volatile const char fallback[TCP_CA_NAME_MAX];
+const char bpf_dctcp[] = "bpf_dctcp";
+const char tcp_cdg[] = "cdg";
+char cc_res[TCP_CA_NAME_MAX];
+int tcp_cdg_res = 0;
+int stg_result = 0;
+int ebusy_cnt = 0;
+
+struct {
+	__uint(type, BPF_MAP_TYPE_SK_STORAGE);
+	__uint(map_flags, BPF_F_NO_PREALLOC);
+	__type(key, int);
+	__type(value, int);
+} sk_stg_map SEC(".maps");
+
 #define DCTCP_MAX_ALPHA	1024U
 
 struct dctcp {
@@ -43,12 +62,45 @@ void BPF_PROG(dctcp_init, struct sock *sk)
 {
 	const struct tcp_sock *tp = tcp_sk(sk);
 	struct dctcp *ca = inet_csk_ca(sk);
+	int *stg;
+
+	if (!(tp->ecn_flags & TCP_ECN_OK) && fallback[0]) {
+		/* Switch to fallback */
+		if (bpf_setsockopt(sk, SOL_TCP, TCP_CONGESTION,
+				   (void *)fallback, sizeof(fallback)) == -EBUSY)
+			ebusy_cnt++;
+
+		/* Switch back to myself and the recurred dctcp_init()
+		 * will get -EBUSY for all bpf_setsockopt(TCP_CONGESTION),
+		 * except the last "cdg" one.
+		 */
+		if (bpf_setsockopt(sk, SOL_TCP, TCP_CONGESTION,
+				   (void *)bpf_dctcp, sizeof(bpf_dctcp)) == -EBUSY)
+			ebusy_cnt++;
+
+		/* Switch back to fallback */
+		if (bpf_setsockopt(sk, SOL_TCP, TCP_CONGESTION,
+				   (void *)fallback, sizeof(fallback)) == -EBUSY)
+			ebusy_cnt++;
+
+		/* Expecting -ENOTSUPP for tcp_cdg_res */
+		tcp_cdg_res = bpf_setsockopt(sk, SOL_TCP, TCP_CONGESTION,
+					     (void *)tcp_cdg, sizeof(tcp_cdg));
+		bpf_getsockopt(sk, SOL_TCP, TCP_CONGESTION,
+			       (void *)cc_res, sizeof(cc_res));
+		return;
+	}
 
 	ca->prior_rcv_nxt = tp->rcv_nxt;
 	ca->dctcp_alpha = min(dctcp_alpha_on_init, DCTCP_MAX_ALPHA);
 	ca->loss_cwnd = 0;
 	ca->ce_state = 0;
 
+	stg = bpf_sk_storage_get(&sk_stg_map, (void *)tp, NULL, 0);
+	if (stg) {
+		stg_result = *stg;
+		bpf_sk_storage_delete(&sk_stg_map, (void *)tp);
+	}
 	dctcp_reset(tp, ca);
 }
 
@@ -176,22 +228,12 @@ __u32 BPF_PROG(dctcp_cwnd_undo, struct sock *sk)
 	return max(tcp_sk(sk)->snd_cwnd, ca->loss_cwnd);
 }
 
-SEC("struct_ops/tcp_reno_cong_avoid")
-void BPF_PROG(tcp_reno_cong_avoid, struct sock *sk, __u32 ack, __u32 acked)
-{
-	struct tcp_sock *tp = tcp_sk(sk);
-
-	if (!tcp_is_cwnd_limited(sk))
-		return;
+extern void tcp_reno_cong_avoid(struct sock *sk, __u32 ack, __u32 acked) __ksym;
 
-	/* In "safe" area, increase. */
-	if (tcp_in_slow_start(tp)) {
-		acked = tcp_slow_start(tp, acked);
-		if (!acked)
-			return;
-	}
-	/* In dangerous area, increase slowly. */
-	tcp_cong_avoid_ai(tp, tp->snd_cwnd, acked);
+SEC("struct_ops/dctcp_reno_cong_avoid")
+void BPF_PROG(dctcp_cong_avoid, struct sock *sk, __u32 ack, __u32 acked)
+{
+	tcp_reno_cong_avoid(sk, ack, acked);
 }
 
 SEC(".struct_ops")
@@ -208,7 +250,7 @@ struct tcp_congestion_ops dctcp = {
 	.in_ack_event   = (void *)dctcp_update_alpha,
 	.cwnd_event	= (void *)dctcp_cwnd_event,
 	.ssthresh	= (void *)dctcp_ssthresh,
-	.cong_avoid	= (void *)tcp_reno_cong_avoid,
+	.cong_avoid	= (void *)dctcp_cong_avoid,
 	.undo_cwnd	= (void *)dctcp_cwnd_undo,
 	.set_state	= (void *)dctcp_state,
 	.flags		= TCP_CONG_NEEDS_ECN,