[PATCH mptcp-next v13 7/9] mptcp: add call_me_again flag

[Geliang Tang <geliang.tang@suse.com>]

For supporting a "redundant" packet scheduler in the future, this patch
adds a flag of struct mptcp_sock named call_me_again to indicate that
get_subflow() function needs to be called again.

Export it in bpf_mptcp_helpers.h, and add BPF write access to it.

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
---
 net/mptcp/bpf.c                                 | 16 ++++++++++++++++
 net/mptcp/protocol.h                            |  1 +
 net/mptcp/sched.c                               |  1 +
 tools/testing/selftests/bpf/bpf_mptcp_helpers.h |  1 +
 4 files changed, 19 insertions(+)

diff --git a/net/mptcp/bpf.c b/net/mptcp/bpf.c
index e849fc3fb6c5..1611dbe63eb2 100644
--- a/net/mptcp/bpf.c
+++ b/net/mptcp/bpf.c
@@ -40,6 +40,7 @@ static int bpf_mptcp_sched_btf_struct_access(struct bpf_verifier_log *log,
 {
 	const struct btf_type *state;
 	u32 type_id;
+	size_t end;
 
 	if (atype == BPF_READ)
 		return btf_struct_access(log, btf, t, off, size, atype,
@@ -55,6 +56,21 @@ static int bpf_mptcp_sched_btf_struct_access(struct bpf_verifier_log *log,
 		return -EACCES;
 	}
 
+	switch (off) {
+	case offsetofend(struct mptcp_sock, sched):
+		end = offsetofend(struct mptcp_sock, sched) + sizeof(u8);
+		break;
+	default:
+		bpf_log(log, "no write support to mptcp_sock at off %d\n", off);
+		return -EACCES;
+	}
+
+	if (off + size > end) {
+		bpf_log(log, "access beyond mptcp_sock at off %u size %u ended at %zu",
+			off, size, end);
+		return -EACCES;
+	}
+
 	return NOT_INIT;
 }
 
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index f31bc3271bcc..13c6ad5fbade 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -299,6 +299,7 @@ struct mptcp_sock {
 	struct sock	*first;
 	struct mptcp_pm_data	pm;
 	struct mptcp_sched_ops	*sched;
+	u8		call_me_again:1;
 	struct {
 		u32	space;	/* bytes copied in last measurement window */
 		u32	copied; /* bytes copied in this measurement window */
diff --git a/net/mptcp/sched.c b/net/mptcp/sched.c
index 8025dc51fbe9..05ab45505f88 100644
--- a/net/mptcp/sched.c
+++ b/net/mptcp/sched.c
@@ -83,6 +83,7 @@ int mptcp_init_sched(struct mptcp_sock *msk,
 	msk->sched = sched_init;
 	if (msk->sched->init)
 		msk->sched->init(msk);
+	msk->call_me_again = 0;
 
 	pr_debug("sched=%s", msk->sched->name);
 
diff --git a/tools/testing/selftests/bpf/bpf_mptcp_helpers.h b/tools/testing/selftests/bpf/bpf_mptcp_helpers.h
index 81a9c5d91aae..dacee63455f5 100644
--- a/tools/testing/selftests/bpf/bpf_mptcp_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_mptcp_helpers.h
@@ -24,6 +24,7 @@ struct mptcp_sock {
 	__u32		token;
 	struct sock	*first;
 	struct mptcp_sched_ops *sched;
+	__u8		call_me_again:1;
 	char		ca_name[TCP_CA_NAME_MAX];
 } __attribute__((preserve_access_index));
 
-- 
2.34.1