[PATCH mptcp-next v10 0/8] BPF packet scheduler

[PATCH mptcp-next v10 0/8] BPF packet scheduler

[Geliang Tang]

v10:
 - patch 5: keep msk->last_snd setting in get_subflow().
 - patch 6: add bpf_mptcp_sched_btf_struct_access().
 - patch 8: use MIN() in sys/param.h, instead of defining a new one.
 - update commit logs.

base-commit: export/20220406T054706

v9:
 - patch 2: add the missing mptcp_sched_init() invoking in
   mptcp_proto_init().
 - patch 5: set last_snd after invoking get_subflow().
 - patch 7: merge the squash-to patch.

v8:
 - use global sched_list instead of pernet sched_list.
 - drop synchronize_rcu() in mptcp_unregister_scheduler().
 - update mptcp_init_sched and mptcp_release_sched as Mat and Florian
   suggested.
 - fix the build break in patch 8.
 - depends on: "add skc_to_mptcp_sock" v14.
 - export/20220325T055307

v7:
 - add bpf_try_module_get in mptcp_init_sched.
 - add bpf_module_put in mptcp_release_sched.
 - rename bpf_first to mptcp_bpf_first.
 - update commit logs.

v6:
 - still use pernet sched_list, use current->nsproxy->net_ns in BPF
   context instead of using init_net.
 - patch 1:
   - use rcu_read_lock instead of spin_lock in mptcp_sched_find as Florian suggested.
   - drop synchronize_rcu in sched_exit_net as Florian suggested.
   - keep synchronize_rcu in mptcp_unregister_scheduler, otherwise, got
     a workqueue lockup in my test.
   - update Makefile as Mat suggested.
 - patch 2:
   - add mptcp_sched_data_init to register default sched, instead of
     registering it in init_net.
 - patch 5:
   - move mptcp_sched_get_subflow to protocol.h as Mat suggested.
 - patch 6:
   - use current->nsproxy->net_ns instead of init_net.
 - patch 8:
   - add send_data to send more data, instead of send_byte.

v5:
 - patch 1: define per-namespace sched_list (but only used init_net
   namespace. It is difficult to get 'net' in bpf_mptcp_sched_reg and
   bpf_mptcp_sched_unreg. I need some suggestions here.)
 - patch 2: skip mptcp_sched_default in mptcp_unregister_scheduler.
 - patch 8: add tests into mptcp.c, instead of bpf_tcp_ca.c.

v4:
 - set msk->sched to &mptcp_sched_default when the sched argument is NULL
in mptcp_init_sched().

v3:
 - add mptcp_release_sched helper in patch 4.
 - rename mptcp_set_sched to mptcp_init_sched in patch 4.
 - add mptcp_sched_first_release in patch 7.
 - do some cleanups.

v2:
 - split into more small patches.
 - change all parameters of mptcp_sched_ops from sk to msk:
       void (*init)(struct mptcp_sock *msk);
       void (*release)(struct mptcp_sock *msk);
       struct sock *   (*get_subflow)(struct mptcp_sock *msk);
 - add tests in bpf_tcp_ca.c, instead of adding a new one.

v1:
 - Addressed to the commends in the RFC version.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/75

Geliang Tang (8):
  mptcp: add struct mptcp_sched_ops
  mptcp: register default scheduler
  mptcp: add a new sysctl scheduler
  mptcp: add sched in mptcp_sock
  mptcp: add get_subflow wrapper
  mptcp: add bpf_mptcp_sched_ops
  selftests: bpf: add bpf_first scheduler
  selftests: bpf: add bpf_first test

 Documentation/networking/mptcp-sysctl.rst     |   8 ++
 include/net/mptcp.h                           |  13 ++
 kernel/bpf/bpf_struct_ops_types.h             |   4 +
 net/mptcp/Makefile                            |   2 +-
 net/mptcp/bpf.c                               | 129 ++++++++++++++++++
 net/mptcp/ctrl.c                              |  14 ++
 net/mptcp/protocol.c                          |  16 ++-
 net/mptcp/protocol.h                          |  16 +++
 net/mptcp/sched.c                             | 104 ++++++++++++++
 .../testing/selftests/bpf/bpf_mptcp_helpers.h |  12 ++
 .../testing/selftests/bpf/prog_tests/mptcp.c  | 113 +++++++++++++++
 .../selftests/bpf/progs/mptcp_bpf_first.c     |  30 ++++
 12 files changed, 456 insertions(+), 5 deletions(-)
 create mode 100644 net/mptcp/sched.c
 create mode 100644 tools/testing/selftests/bpf/progs/mptcp_bpf_first.c

-- 
2.34.1

[PATCH mptcp-next v10 1/8] mptcp: add struct mptcp_sched_ops

[Geliang Tang]

This patch defines struct mptcp_sched_ops, which has three struct members,
name, owner and list, and three function pointers, init, release and
get_subflow.

Add the scheduler registering, unregistering and finding functions to add,
delete and find a packet scheduler on the global list mptcp_sched_list.

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
---
 include/net/mptcp.h  | 13 ++++++++++
 net/mptcp/Makefile   |  2 +-
 net/mptcp/protocol.h |  3 +++
 net/mptcp/sched.c    | 56 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 73 insertions(+), 1 deletion(-)
 create mode 100644 net/mptcp/sched.c

diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 877077b53200..aea7ed9a2250 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -95,6 +95,19 @@ struct mptcp_out_options {
 #endif
 };
 
+#define MPTCP_SCHED_NAME_MAX 16
+
+struct mptcp_sched_ops {
+	struct sock *	(*get_subflow)(struct mptcp_sock *msk);
+
+	char			name[MPTCP_SCHED_NAME_MAX];
+	struct module		*owner;
+	struct list_head	list;
+
+	void (*init)(struct mptcp_sock *msk);
+	void (*release)(struct mptcp_sock *msk);
+} ____cacheline_aligned_in_smp;
+
 #ifdef CONFIG_MPTCP
 extern struct request_sock_ops mptcp_subflow_request_sock_ops;
 
diff --git a/net/mptcp/Makefile b/net/mptcp/Makefile
index 168c55d1c917..a37330760b0c 100644
--- a/net/mptcp/Makefile
+++ b/net/mptcp/Makefile
@@ -2,7 +2,7 @@
 obj-$(CONFIG_MPTCP) += mptcp.o
 
 mptcp-y := protocol.o subflow.o options.o token.o crypto.o ctrl.o pm.o diag.o \
-	   mib.o pm_netlink.o sockopt.o
+	   mib.o pm_netlink.o sockopt.o sched.o
 
 obj-$(CONFIG_SYN_COOKIES) += syncookies.o
 obj-$(CONFIG_INET_MPTCP_DIAG) += mptcp_diag.o
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 187c932deef0..7cd2c1c3d25c 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -608,6 +608,9 @@ int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock);
 void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
 			 struct sockaddr_storage *addr,
 			 unsigned short family);
+struct mptcp_sched_ops *mptcp_sched_find(const char *name);
+int mptcp_register_scheduler(struct mptcp_sched_ops *sched);
+void mptcp_unregister_scheduler(struct mptcp_sched_ops *sched);
 
 static inline bool __mptcp_subflow_active(struct mptcp_subflow_context *subflow)
 {
diff --git a/net/mptcp/sched.c b/net/mptcp/sched.c
new file mode 100644
index 000000000000..c5d3bbafba71
--- /dev/null
+++ b/net/mptcp/sched.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Multipath TCP
+ *
+ * Copyright (c) 2022, SUSE.
+ */
+
+#define pr_fmt(fmt) "MPTCP: " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/rculist.h>
+#include <linux/spinlock.h>
+#include "protocol.h"
+
+static DEFINE_SPINLOCK(mptcp_sched_list_lock);
+static LIST_HEAD(mptcp_sched_list);
+
+/* Must be called with rcu read lock held */
+struct mptcp_sched_ops *mptcp_sched_find(const char *name)
+{
+	struct mptcp_sched_ops *sched, *ret = NULL;
+
+	list_for_each_entry_rcu(sched, &mptcp_sched_list, list) {
+		if (!strcmp(sched->name, name)) {
+			ret = sched;
+			break;
+		}
+	}
+
+	return ret;
+}
+
+int mptcp_register_scheduler(struct mptcp_sched_ops *sched)
+{
+	if (!sched->get_subflow)
+		return -EINVAL;
+
+	spin_lock(&mptcp_sched_list_lock);
+	if (mptcp_sched_find(sched->name)) {
+		spin_unlock(&mptcp_sched_list_lock);
+		return -EEXIST;
+	}
+	list_add_tail_rcu(&sched->list, &mptcp_sched_list);
+	spin_unlock(&mptcp_sched_list_lock);
+
+	pr_debug("%s registered", sched->name);
+	return 0;
+}
+
+void mptcp_unregister_scheduler(struct mptcp_sched_ops *sched)
+{
+	spin_lock(&mptcp_sched_list_lock);
+	list_del_rcu(&sched->list);
+	spin_unlock(&mptcp_sched_list_lock);
+}
-- 
2.34.1

[PATCH mptcp-next v10 2/8] mptcp: register default scheduler

[Geliang Tang]

This patch defines the default packet scheduler mptcp_sched_default,
register it in mptcp_sched_init(), which is invoked in mptcp_proto_init().
Skip deleting this default scheduler in mptcp_unregister_scheduler().

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
---
 net/mptcp/protocol.c |  3 ++-
 net/mptcp/protocol.h |  2 ++
 net/mptcp/sched.c    | 14 ++++++++++++++
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index b2c654992de0..8f0e71c38336 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1424,7 +1424,7 @@ bool mptcp_subflow_active(struct mptcp_subflow_context *subflow)
  * returns the subflow that will transmit the next DSS
  * additionally updates the rtx timeout
  */
-static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
+struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
 {
 	struct subflow_send_info send_info[SSK_MODE_MAX];
 	struct mptcp_subflow_context *subflow;
@@ -3804,6 +3804,7 @@ void __init mptcp_proto_init(void)
 
 	mptcp_subflow_init();
 	mptcp_pm_init();
+	mptcp_sched_init();
 	mptcp_token_init();
 
 	if (proto_register(&mptcp_prot, MPTCP_USE_SLAB) != 0)
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 7cd2c1c3d25c..a264964f8d95 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -611,6 +611,8 @@ void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
 struct mptcp_sched_ops *mptcp_sched_find(const char *name);
 int mptcp_register_scheduler(struct mptcp_sched_ops *sched);
 void mptcp_unregister_scheduler(struct mptcp_sched_ops *sched);
+struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk);
+void mptcp_sched_init(void);
 
 static inline bool __mptcp_subflow_active(struct mptcp_subflow_context *subflow)
 {
diff --git a/net/mptcp/sched.c b/net/mptcp/sched.c
index c5d3bbafba71..52828eb741c0 100644
--- a/net/mptcp/sched.c
+++ b/net/mptcp/sched.c
@@ -13,6 +13,12 @@
 #include <linux/spinlock.h>
 #include "protocol.h"
 
+static struct mptcp_sched_ops mptcp_sched_default = {
+	.get_subflow    = mptcp_subflow_get_send,
+	.name           = "default",
+	.owner          = THIS_MODULE,
+};
+
 static DEFINE_SPINLOCK(mptcp_sched_list_lock);
 static LIST_HEAD(mptcp_sched_list);
 
@@ -50,7 +56,15 @@ int mptcp_register_scheduler(struct mptcp_sched_ops *sched)
 
 void mptcp_unregister_scheduler(struct mptcp_sched_ops *sched)
 {
+	if (sched == &mptcp_sched_default)
+		return;
+
 	spin_lock(&mptcp_sched_list_lock);
 	list_del_rcu(&sched->list);
 	spin_unlock(&mptcp_sched_list_lock);
 }
+
+void mptcp_sched_init(void)
+{
+	mptcp_register_scheduler(&mptcp_sched_default);
+}
-- 
2.34.1

[PATCH mptcp-next v10 3/8] mptcp: add a new sysctl scheduler

[Geliang Tang]

This patch adds a new sysctl, named scheduler, to support for selection
of different schedulers. Export mptcp_get_scheduler helper to get this
sysctl.

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
---
 Documentation/networking/mptcp-sysctl.rst |  8 ++++++++
 net/mptcp/ctrl.c                          | 14 ++++++++++++++
 net/mptcp/protocol.h                      |  1 +
 3 files changed, 23 insertions(+)

diff --git a/Documentation/networking/mptcp-sysctl.rst b/Documentation/networking/mptcp-sysctl.rst
index e263dfcc4b40..d9e69fdc7ea3 100644
--- a/Documentation/networking/mptcp-sysctl.rst
+++ b/Documentation/networking/mptcp-sysctl.rst
@@ -75,3 +75,11 @@ stale_loss_cnt - INTEGER
 	This is a per-namespace sysctl.
 
 	Default: 4
+
+scheduler - STRING
+	Select the scheduler of your choice.
+
+	Support for selection of different schedulers. This is a per-namespace
+	sysctl.
+
+	Default: "default"
diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
index ae20b7d92e28..c46c22a84d23 100644
--- a/net/mptcp/ctrl.c
+++ b/net/mptcp/ctrl.c
@@ -32,6 +32,7 @@ struct mptcp_pernet {
 	u8 checksum_enabled;
 	u8 allow_join_initial_addr_port;
 	u8 pm_type;
+	char scheduler[MPTCP_SCHED_NAME_MAX];
 };
 
 static struct mptcp_pernet *mptcp_get_pernet(const struct net *net)
@@ -69,6 +70,11 @@ int mptcp_get_pm_type(const struct net *net)
 	return mptcp_get_pernet(net)->pm_type;
 }
 
+const char *mptcp_get_scheduler(const struct net *net)
+{
+	return mptcp_get_pernet(net)->scheduler;
+}
+
 static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet)
 {
 	pernet->mptcp_enabled = 1;
@@ -77,6 +83,7 @@ static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet)
 	pernet->allow_join_initial_addr_port = 1;
 	pernet->stale_loss_cnt = 4;
 	pernet->pm_type = MPTCP_PM_TYPE_KERNEL;
+	strcpy(pernet->scheduler, "default");
 }
 
 #ifdef CONFIG_SYSCTL
@@ -128,6 +135,12 @@ static struct ctl_table mptcp_sysctl_table[] = {
 		.extra1       = SYSCTL_ZERO,
 		.extra2       = &mptcp_pm_type_max
 	},
+	{
+		.procname = "scheduler",
+		.maxlen	= MPTCP_SCHED_NAME_MAX,
+		.mode = 0644,
+		.proc_handler = proc_dostring,
+	},
 	{}
 };
 
@@ -149,6 +162,7 @@ static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet)
 	table[3].data = &pernet->allow_join_initial_addr_port;
 	table[4].data = &pernet->stale_loss_cnt;
 	table[5].data = &pernet->pm_type;
+	table[6].data = &pernet->scheduler;
 
 	hdr = register_net_sysctl(net, MPTCP_SYSCTL_PATH, table);
 	if (!hdr)
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index a264964f8d95..65a08110268d 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -586,6 +586,7 @@ int mptcp_is_checksum_enabled(const struct net *net);
 int mptcp_allow_join_id0(const struct net *net);
 unsigned int mptcp_stale_loss_cnt(const struct net *net);
 int mptcp_get_pm_type(const struct net *net);
+const char *mptcp_get_scheduler(const struct net *net);
 void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
 				     struct mptcp_options_received *mp_opt);
 bool __mptcp_retransmit_pending_data(struct sock *sk);
-- 
2.34.1

[PATCH mptcp-next v10 4/8] mptcp: add sched in mptcp_sock

[Geliang Tang]

This patch adds a new struct member sched in struct mptcp_sock.
And two helpers mptcp_init_sched() and mptcp_release_sched() to
init and release it.

Init it with the sysctl scheduler in mptcp_init_sock(), copy the
scheduler from the parent in mptcp_sk_clone(), and release it in
__mptcp_destroy_sock().

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
---
 net/mptcp/protocol.c |  7 +++++++
 net/mptcp/protocol.h |  4 ++++
 net/mptcp/sched.c    | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 45 insertions(+)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 8f0e71c38336..37f4f6f3661d 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2657,6 +2657,11 @@ static int mptcp_init_sock(struct sock *sk)
 	if (ret)
 		return ret;
 
+	ret = mptcp_init_sched(mptcp_sk(sk),
+			       mptcp_sched_find(mptcp_get_scheduler(net)));
+	if (ret)
+		return ret;
+
 	/* fetch the ca name; do it outside __mptcp_init_sock(), so that clone will
 	 * propagate the correct value
 	 */
@@ -2816,6 +2821,7 @@ static void __mptcp_destroy_sock(struct sock *sk)
 	sk_stop_timer(sk, &sk->sk_timer);
 	mptcp_data_unlock(sk);
 	msk->pm.status = 0;
+	mptcp_release_sched(msk);
 
 	/* clears msk->subflow, allowing the following loop to close
 	 * even the initial subflow
@@ -2993,6 +2999,7 @@ struct sock *mptcp_sk_clone(const struct sock *sk,
 	msk->snd_una = msk->write_seq;
 	msk->wnd_end = msk->snd_nxt + req->rsk_rcv_wnd;
 	msk->setsockopt_seq = mptcp_sk(sk)->setsockopt_seq;
+	mptcp_init_sched(msk, mptcp_sk(sk)->sched);
 
 	if (mp_opt->suboptions & OPTIONS_MPTCP_MPC) {
 		msk->can_ack = true;
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 65a08110268d..1016dac065c8 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -288,6 +288,7 @@ struct mptcp_sock {
 	struct socket	*subflow; /* outgoing connect/listener/!mp_capable */
 	struct sock	*first;
 	struct mptcp_pm_data	pm;
+	struct mptcp_sched_ops	*sched;
 	struct {
 		u32	space;	/* bytes copied in last measurement window */
 		u32	copied; /* bytes copied in this measurement window */
@@ -614,6 +615,9 @@ int mptcp_register_scheduler(struct mptcp_sched_ops *sched);
 void mptcp_unregister_scheduler(struct mptcp_sched_ops *sched);
 struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk);
 void mptcp_sched_init(void);
+int mptcp_init_sched(struct mptcp_sock *msk,
+		     struct mptcp_sched_ops *sched);
+void mptcp_release_sched(struct mptcp_sock *msk);
 
 static inline bool __mptcp_subflow_active(struct mptcp_subflow_context *subflow)
 {
diff --git a/net/mptcp/sched.c b/net/mptcp/sched.c
index 52828eb741c0..5d20d252088f 100644
--- a/net/mptcp/sched.c
+++ b/net/mptcp/sched.c
@@ -68,3 +68,37 @@ void mptcp_sched_init(void)
 {
 	mptcp_register_scheduler(&mptcp_sched_default);
 }
+
+int mptcp_init_sched(struct mptcp_sock *msk,
+		     struct mptcp_sched_ops *sched)
+{
+	struct mptcp_sched_ops *sched_init = &mptcp_sched_default;
+
+	if (sched)
+		sched_init = sched;
+
+	if (!bpf_try_module_get(sched_init, sched_init->owner))
+		return -EBUSY;
+
+	msk->sched = sched_init;
+	if (msk->sched->init)
+		msk->sched->init(msk);
+
+	pr_debug("sched=%s", msk->sched->name);
+
+	return 0;
+}
+
+void mptcp_release_sched(struct mptcp_sock *msk)
+{
+	struct mptcp_sched_ops *sched = msk->sched;
+
+	if (!sched)
+		return;
+
+	msk->sched = NULL;
+	if (sched->release)
+		sched->release(msk);
+
+	bpf_module_put(sched, sched->owner);
+}
-- 
2.34.1

[PATCH mptcp-next v10 5/8] mptcp: add get_subflow wrapper

[Geliang Tang]

This patch defines a new wrapper mptcp_sched_get_subflow(), invoke
get_subflow() of msk->sched in it. Use the wrapper instead of using
mptcp_subflow_get_send() directly.

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
---
 net/mptcp/protocol.c | 6 +++---
 net/mptcp/protocol.h | 6 ++++++
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 37f4f6f3661d..91d8a6f2c38b 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1567,7 +1567,7 @@ void __mptcp_push_pending(struct sock *sk, unsigned int flags)
 			int ret = 0;
 
 			prev_ssk = ssk;
-			ssk = mptcp_subflow_get_send(msk);
+			ssk = mptcp_sched_get_subflow(msk);
 
 			/* First check. If the ssk has changed since
 			 * the last round, release prev_ssk
@@ -1636,7 +1636,7 @@ static void __mptcp_subflow_push_pending(struct sock *sk, struct sock *ssk)
 			 * check for a different subflow usage only after
 			 * spooling the first chunk of data
 			 */
-			xmit_ssk = first ? ssk : mptcp_subflow_get_send(mptcp_sk(sk));
+			xmit_ssk = first ? ssk : mptcp_sched_get_subflow(mptcp_sk(sk));
 			if (!xmit_ssk)
 				goto out;
 			if (xmit_ssk != ssk) {
@@ -3137,7 +3137,7 @@ void __mptcp_check_push(struct sock *sk, struct sock *ssk)
 		return;
 
 	if (!sock_owned_by_user(sk)) {
-		struct sock *xmit_ssk = mptcp_subflow_get_send(mptcp_sk(sk));
+		struct sock *xmit_ssk = mptcp_sched_get_subflow(mptcp_sk(sk));
 
 		if (xmit_ssk == ssk)
 			__mptcp_subflow_push_pending(sk, ssk);
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 1016dac065c8..60d6ee54a899 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -619,6 +619,12 @@ int mptcp_init_sched(struct mptcp_sock *msk,
 		     struct mptcp_sched_ops *sched);
 void mptcp_release_sched(struct mptcp_sock *msk);
 
+static inline struct sock *mptcp_sched_get_subflow(struct mptcp_sock *msk)
+{
+	return INDIRECT_CALL_INET_1(msk->sched->get_subflow,
+				    mptcp_subflow_get_send, msk);
+}
+
 static inline bool __mptcp_subflow_active(struct mptcp_subflow_context *subflow)
 {
 	struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
-- 
2.34.1

[PATCH mptcp-next v10 6/8] mptcp: add bpf_mptcp_sched_ops

[Geliang Tang]

This patch implements a new struct bpf_struct_ops, bpf_mptcp_sched_ops.
Register and unregister the bpf scheduler in .reg and .unreg.

This MPTCP BPF scheduler implementation is similar to BPF TCP CC. And
net/ipv4/bpf_tcp_ca.c is a frame of reference for this patch.

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
---
 kernel/bpf/bpf_struct_ops_types.h |   4 +
 net/mptcp/bpf.c                   | 129 ++++++++++++++++++++++++++++++
 2 files changed, 133 insertions(+)

diff --git a/kernel/bpf/bpf_struct_ops_types.h b/kernel/bpf/bpf_struct_ops_types.h
index 5678a9ddf817..5a6b0c0d8d3d 100644
--- a/kernel/bpf/bpf_struct_ops_types.h
+++ b/kernel/bpf/bpf_struct_ops_types.h
@@ -8,5 +8,9 @@ BPF_STRUCT_OPS_TYPE(bpf_dummy_ops)
 #ifdef CONFIG_INET
 #include <net/tcp.h>
 BPF_STRUCT_OPS_TYPE(tcp_congestion_ops)
+#ifdef CONFIG_MPTCP
+#include <net/mptcp.h>
+BPF_STRUCT_OPS_TYPE(mptcp_sched_ops)
+#endif
 #endif
 #endif
diff --git a/net/mptcp/bpf.c b/net/mptcp/bpf.c
index 535602ba2582..e849fc3fb6c5 100644
--- a/net/mptcp/bpf.c
+++ b/net/mptcp/bpf.c
@@ -10,8 +10,137 @@
 #define pr_fmt(fmt) "MPTCP: " fmt
 
 #include <linux/bpf.h>
+#include <linux/bpf_verifier.h>
+#include <linux/btf.h>
+#include <linux/btf_ids.h>
 #include "protocol.h"
 
+extern struct bpf_struct_ops bpf_mptcp_sched_ops;
+extern struct btf *btf_vmlinux;
+
+static u32 optional_ops[] = {
+	offsetof(struct mptcp_sched_ops, init),
+	offsetof(struct mptcp_sched_ops, release),
+	offsetof(struct mptcp_sched_ops, get_subflow),
+};
+
+static const struct bpf_func_proto *
+bpf_mptcp_sched_get_func_proto(enum bpf_func_id func_id,
+			       const struct bpf_prog *prog)
+{
+	return bpf_base_func_proto(func_id);
+}
+
+static int bpf_mptcp_sched_btf_struct_access(struct bpf_verifier_log *log,
+					     const struct btf *btf,
+					     const struct btf_type *t, int off,
+					     int size, enum bpf_access_type atype,
+					     u32 *next_btf_id,
+					     enum bpf_type_flag *flag)
+{
+	const struct btf_type *state;
+	u32 type_id;
+
+	if (atype == BPF_READ)
+		return btf_struct_access(log, btf, t, off, size, atype,
+					 next_btf_id, flag);
+
+	type_id = btf_find_by_name_kind(btf, "mptcp_sock", BTF_KIND_STRUCT);
+	if (type_id < 0)
+		return -EINVAL;
+
+	state = btf_type_by_id(btf, type_id);
+	if (t != state) {
+		bpf_log(log, "only read is supported\n");
+		return -EACCES;
+	}
+
+	return NOT_INIT;
+}
+
+static const struct bpf_verifier_ops bpf_mptcp_sched_verifier_ops = {
+	.get_func_proto		= bpf_mptcp_sched_get_func_proto,
+	.is_valid_access	= bpf_tracing_btf_ctx_access,
+	.btf_struct_access	= bpf_mptcp_sched_btf_struct_access,
+};
+
+static int bpf_mptcp_sched_reg(void *kdata)
+{
+	return mptcp_register_scheduler(kdata);
+}
+
+static void bpf_mptcp_sched_unreg(void *kdata)
+{
+	mptcp_unregister_scheduler(kdata);
+}
+
+static int bpf_mptcp_sched_check_member(const struct btf_type *t,
+					const struct btf_member *member)
+{
+	return 0;
+}
+
+static bool is_optional(u32 member_offset)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(optional_ops); i++) {
+		if (member_offset == optional_ops[i])
+			return true;
+	}
+
+	return false;
+}
+
+static int bpf_mptcp_sched_init_member(const struct btf_type *t,
+				       const struct btf_member *member,
+				       void *kdata, const void *udata)
+{
+	const struct mptcp_sched_ops *usched;
+	struct mptcp_sched_ops *sched;
+	int prog_fd;
+	u32 moff;
+
+	usched = (const struct mptcp_sched_ops *)udata;
+	sched = (struct mptcp_sched_ops *)kdata;
+
+	moff = __btf_member_bit_offset(t, member) / 8;
+	switch (moff) {
+	case offsetof(struct mptcp_sched_ops, name):
+		if (bpf_obj_name_cpy(sched->name, usched->name,
+				     sizeof(sched->name)) <= 0)
+			return -EINVAL;
+		if (mptcp_sched_find(usched->name))
+			return -EEXIST;
+		return 1;
+	}
+
+	if (!btf_type_resolve_func_ptr(btf_vmlinux, member->type, NULL))
+		return 0;
+
+	/* Ensure bpf_prog is provided for compulsory func ptr */
+	prog_fd = (int)(*(unsigned long *)(udata + moff));
+	if (!prog_fd && !is_optional(moff))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int bpf_mptcp_sched_init(struct btf *btf)
+{
+	return 0;
+}
+
+struct bpf_struct_ops bpf_mptcp_sched_ops = {
+	.verifier_ops	= &bpf_mptcp_sched_verifier_ops,
+	.reg		= bpf_mptcp_sched_reg,
+	.unreg		= bpf_mptcp_sched_unreg,
+	.check_member	= bpf_mptcp_sched_check_member,
+	.init_member	= bpf_mptcp_sched_init_member,
+	.init		= bpf_mptcp_sched_init,
+	.name		= "mptcp_sched_ops",
+};
+
 struct mptcp_sock *bpf_mptcp_sock_from_subflow(struct sock *sk)
 {
 	if (sk && sk_fullsock(sk) && sk->sk_protocol == IPPROTO_TCP && sk_is_mptcp(sk))
-- 
2.34.1

[PATCH mptcp-next v10 7/8] selftests: bpf: add bpf_first scheduler

[Geliang Tang]

This patch implements the simplest MPTCP scheduler, named bpf_first,
which always picks the first subflow to send data. It's a sample of
MPTCP BPF scheduler implementations.

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
---
 .../testing/selftests/bpf/bpf_mptcp_helpers.h | 12 ++++++++
 .../selftests/bpf/progs/mptcp_bpf_first.c     | 30 +++++++++++++++++++
 2 files changed, 42 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/mptcp_bpf_first.c

diff --git a/tools/testing/selftests/bpf/bpf_mptcp_helpers.h b/tools/testing/selftests/bpf/bpf_mptcp_helpers.h
index b5a43b108982..5135eb6710e8 100644
--- a/tools/testing/selftests/bpf/bpf_mptcp_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_mptcp_helpers.h
@@ -14,4 +14,16 @@ struct mptcp_sock {
 	char		ca_name[TCP_CA_NAME_MAX];
 } __attribute__((preserve_access_index));
 
+#define MPTCP_SCHED_NAME_MAX 16
+
+struct mptcp_sched_ops {
+	char name[MPTCP_SCHED_NAME_MAX];
+
+	void (*init)(struct mptcp_sock *msk);
+	void (*release)(struct mptcp_sock *msk);
+
+	struct sock *	(*get_subflow)(struct mptcp_sock *msk);
+	void *owner;
+};
+
 #endif
diff --git a/tools/testing/selftests/bpf/progs/mptcp_bpf_first.c b/tools/testing/selftests/bpf/progs/mptcp_bpf_first.c
new file mode 100644
index 000000000000..b1f9a376ab75
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/mptcp_bpf_first.c
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022, SUSE. */
+
+#include <linux/bpf.h>
+#include "bpf_mptcp_helpers.h"
+
+char _license[] SEC("license") = "GPL";
+
+SEC("struct_ops/mptcp_sched_first_init")
+void BPF_PROG(mptcp_sched_first_init, struct mptcp_sock *msk)
+{
+}
+
+SEC("struct_ops/mptcp_sched_first_release")
+void BPF_PROG(mptcp_sched_first_release, struct mptcp_sock *msk)
+{
+}
+
+struct sock *BPF_STRUCT_OPS(bpf_first_get_subflow, struct mptcp_sock *msk)
+{
+	return msk->first;
+}
+
+SEC(".struct_ops")
+struct mptcp_sched_ops first = {
+	.init		= (void *)mptcp_sched_first_init,
+	.release	= (void *)mptcp_sched_first_release,
+	.get_subflow	= (void *)bpf_first_get_subflow,
+	.name		= "bpf_first",
+};
-- 
2.34.1

[PATCH mptcp-next v10 8/8] selftests: bpf: add bpf_first test

[Geliang Tang]

This patch expends the MPTCP test base to support MPTCP packet
scheduler tests. Add the bpf_first scheduler test in it. Use sysctl
to set net.mptcp.scheduler to use this sched.

Some code in send_data() is from prog_tests/bpf_tcp_ca.c.

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
---
 .../testing/selftests/bpf/prog_tests/mptcp.c  | 113 ++++++++++++++++++
 1 file changed, 113 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/mptcp.c b/tools/testing/selftests/bpf/prog_tests/mptcp.c
index 7e704f5aab05..377ebc0fbcbe 100644
--- a/tools/testing/selftests/bpf/prog_tests/mptcp.c
+++ b/tools/testing/selftests/bpf/prog_tests/mptcp.c
@@ -1,9 +1,11 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (c) 2020, Tessares SA. */
 
+#include <sys/param.h>
 #include <test_progs.h>
 #include "cgroup_helpers.h"
 #include "network_helpers.h"
+#include "mptcp_bpf_first.skel.h"
 
 #ifndef TCP_CA_NAME_MAX
 #define TCP_CA_NAME_MAX	16
@@ -19,6 +21,8 @@ struct mptcp_storage {
 };
 
 static char monitor_log_path[64];
+static const unsigned int total_bytes = 10 * 1024 * 1024;
+static int stop, duration;
 
 static int verify_tsk(int map_fd, int client_fd)
 {
@@ -251,8 +255,117 @@ void test_base(void)
 	close(cgroup_fd);
 }
 
+static void *server(void *arg)
+{
+	int lfd = (int)(long)arg, err = 0, fd;
+	ssize_t nr_sent = 0, bytes = 0;
+	char batch[1500];
+
+	fd = accept(lfd, NULL, NULL);
+	while (fd == -1) {
+		if (errno == EINTR)
+			continue;
+		err = -errno;
+		goto done;
+	}
+
+	if (settimeo(fd, 0)) {
+		err = -errno;
+		goto done;
+	}
+
+	while (bytes < total_bytes && !READ_ONCE(stop)) {
+		nr_sent = send(fd, &batch,
+			       MIN(total_bytes - bytes, sizeof(batch)), 0);
+		if (nr_sent == -1 && errno == EINTR)
+			continue;
+		if (nr_sent == -1) {
+			err = -errno;
+			break;
+		}
+		bytes += nr_sent;
+	}
+
+	CHECK(bytes != total_bytes, "send", "%zd != %u nr_sent:%zd errno:%d\n",
+	      bytes, total_bytes, nr_sent, errno);
+
+done:
+	if (fd >= 0)
+		close(fd);
+	if (err) {
+		WRITE_ONCE(stop, 1);
+		return ERR_PTR(err);
+	}
+	return NULL;
+}
+
+static void send_data(int lfd, int fd)
+{
+	ssize_t nr_recv = 0, bytes = 0;
+	pthread_t srv_thread;
+	void *thread_ret;
+	char batch[1500];
+	int err;
+
+	WRITE_ONCE(stop, 0);
+
+	err = pthread_create(&srv_thread, NULL, server, (void *)(long)lfd);
+	if (CHECK(err != 0, "pthread_create", "err:%d errno:%d\n", err, errno))
+		return;
+
+	/* recv total_bytes */
+	while (bytes < total_bytes && !READ_ONCE(stop)) {
+		nr_recv = recv(fd, &batch,
+			       MIN(total_bytes - bytes, sizeof(batch)), 0);
+		if (nr_recv == -1 && errno == EINTR)
+			continue;
+		if (nr_recv == -1)
+			break;
+		bytes += nr_recv;
+	}
+
+	CHECK(bytes != total_bytes, "recv", "%zd != %u nr_recv:%zd errno:%d\n",
+	      bytes, total_bytes, nr_recv, errno);
+
+	WRITE_ONCE(stop, 1);
+
+	pthread_join(srv_thread, &thread_ret);
+	CHECK(IS_ERR(thread_ret), "pthread_join", "thread_ret:%ld",
+	      PTR_ERR(thread_ret));
+}
+
+static void test_first(void)
+{
+	struct mptcp_bpf_first *first_skel;
+	int server_fd, client_fd;
+	struct bpf_link *link;
+
+	first_skel = mptcp_bpf_first__open_and_load();
+	if (CHECK(!first_skel, "bpf_first__open_and_load", "failed\n"))
+		return;
+
+	link = bpf_map__attach_struct_ops(first_skel->maps.first);
+	if (!ASSERT_OK_PTR(link, "bpf_map__attach_struct_ops")) {
+		mptcp_bpf_first__destroy(first_skel);
+		return;
+	}
+
+	system("sysctl -q net.mptcp.scheduler=bpf_first");
+	server_fd = start_mptcp_server(AF_INET, NULL, 0, 0);
+	client_fd = connect_to_mptcp_fd(server_fd, 0);
+
+	send_data(server_fd, client_fd);
+
+	close(client_fd);
+	close(server_fd);
+	bpf_link__destroy(link);
+	mptcp_bpf_first__destroy(first_skel);
+}
+
 void test_mptcp(void)
 {
 	if (test__start_subtest("base"))
 		test_base();
+	if (test__start_subtest("first"))
+		test_first();
 }
-- 
2.34.1

Re: selftests: bpf: add bpf_first test: Tests Results

[MPTCP CI]

Hi Geliang,

Thank you for your modifications, that's great!

Our CI did some validations and here is its report:

- KVM Validation: normal:
  - Success! ✅:
  - Task: https://cirrus-ci.com/task/6286185919152128
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/6286185919152128/summary/summary.txt

- KVM Validation: debug:
  - Unstable: 1 failed test(s): selftest_diag 🔴:
  - Task: https://cirrus-ci.com/task/6423686008799232
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/6423686008799232/summary/summary.txt

Initiator: Patchew Applier
Commits: https://github.com/multipath-tcp/mptcp_net-next/commits/0897208a28b5

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)

Re: [PATCH mptcp-next v10 0/8] BPF packet scheduler

[Mat Martineau]

On Thu, 7 Apr 2022, Geliang Tang wrote:

> v10:
> - patch 5: keep msk->last_snd setting in get_subflow().
> - patch 6: add bpf_mptcp_sched_btf_struct_access().
> - patch 8: use MIN() in sys/param.h, instead of defining a new one.
> - update commit logs.
>
> base-commit: export/20220406T054706
>

Hi Geliang -

Thanks for updating for v10.

One thing we talked about in the meeting today morning was that the 
in-kernel scheduler doesn't use mptcp_subflow_get_send(), it uses 
mptcp_subflow_get_retrans(). The BPF scheduler needs to handle resends 
too. I think only one BPF hook is still needed, but with an arg that says 
whether it's a resend or not.

Also, the out-of-tree MPTCP kernel scheduler allows for sending 
simulataneously on multiple subflows. This would require a way for the BPF 
hook to return more than one ssk (or maybe some other representation of 
the subflows), and then a way for the MPTCP tx/rtx code to send on 
multiple ssks. Mattheiu, do you know anything about how often the 
'redundant' scheduler is used?

- Mat


> v9:
> - patch 2: add the missing mptcp_sched_init() invoking in
>   mptcp_proto_init().
> - patch 5: set last_snd after invoking get_subflow().
> - patch 7: merge the squash-to patch.
>
> v8:
> - use global sched_list instead of pernet sched_list.
> - drop synchronize_rcu() in mptcp_unregister_scheduler().
> - update mptcp_init_sched and mptcp_release_sched as Mat and Florian
>   suggested.
> - fix the build break in patch 8.
> - depends on: "add skc_to_mptcp_sock" v14.
> - export/20220325T055307
>
> v7:
> - add bpf_try_module_get in mptcp_init_sched.
> - add bpf_module_put in mptcp_release_sched.
> - rename bpf_first to mptcp_bpf_first.
> - update commit logs.
>
> v6:
> - still use pernet sched_list, use current->nsproxy->net_ns in BPF
>   context instead of using init_net.
> - patch 1:
>   - use rcu_read_lock instead of spin_lock in mptcp_sched_find as Florian suggested.
>   - drop synchronize_rcu in sched_exit_net as Florian suggested.
>   - keep synchronize_rcu in mptcp_unregister_scheduler, otherwise, got
>     a workqueue lockup in my test.
>   - update Makefile as Mat suggested.
> - patch 2:
>   - add mptcp_sched_data_init to register default sched, instead of
>     registering it in init_net.
> - patch 5:
>   - move mptcp_sched_get_subflow to protocol.h as Mat suggested.
> - patch 6:
>   - use current->nsproxy->net_ns instead of init_net.
> - patch 8:
>   - add send_data to send more data, instead of send_byte.
>
> v5:
> - patch 1: define per-namespace sched_list (but only used init_net
>   namespace. It is difficult to get 'net' in bpf_mptcp_sched_reg and
>   bpf_mptcp_sched_unreg. I need some suggestions here.)
> - patch 2: skip mptcp_sched_default in mptcp_unregister_scheduler.
> - patch 8: add tests into mptcp.c, instead of bpf_tcp_ca.c.
>
> v4:
> - set msk->sched to &mptcp_sched_default when the sched argument is NULL
> in mptcp_init_sched().
>
> v3:
> - add mptcp_release_sched helper in patch 4.
> - rename mptcp_set_sched to mptcp_init_sched in patch 4.
> - add mptcp_sched_first_release in patch 7.
> - do some cleanups.
>
> v2:
> - split into more small patches.
> - change all parameters of mptcp_sched_ops from sk to msk:
>       void (*init)(struct mptcp_sock *msk);
>       void (*release)(struct mptcp_sock *msk);
>       struct sock *   (*get_subflow)(struct mptcp_sock *msk);
> - add tests in bpf_tcp_ca.c, instead of adding a new one.
>
> v1:
> - Addressed to the commends in the RFC version.
>
> Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/75
>
> Geliang Tang (8):
>  mptcp: add struct mptcp_sched_ops
>  mptcp: register default scheduler
>  mptcp: add a new sysctl scheduler
>  mptcp: add sched in mptcp_sock
>  mptcp: add get_subflow wrapper
>  mptcp: add bpf_mptcp_sched_ops
>  selftests: bpf: add bpf_first scheduler
>  selftests: bpf: add bpf_first test
>
> Documentation/networking/mptcp-sysctl.rst     |   8 ++
> include/net/mptcp.h                           |  13 ++
> kernel/bpf/bpf_struct_ops_types.h             |   4 +
> net/mptcp/Makefile                            |   2 +-
> net/mptcp/bpf.c                               | 129 ++++++++++++++++++
> net/mptcp/ctrl.c                              |  14 ++
> net/mptcp/protocol.c                          |  16 ++-
> net/mptcp/protocol.h                          |  16 +++
> net/mptcp/sched.c                             | 104 ++++++++++++++
> .../testing/selftests/bpf/bpf_mptcp_helpers.h |  12 ++
> .../testing/selftests/bpf/prog_tests/mptcp.c  | 113 +++++++++++++++
> .../selftests/bpf/progs/mptcp_bpf_first.c     |  30 ++++
> 12 files changed, 456 insertions(+), 5 deletions(-)
> create mode 100644 net/mptcp/sched.c
> create mode 100644 tools/testing/selftests/bpf/progs/mptcp_bpf_first.c
>
> -- 
> 2.34.1
>
>
>

--
Mat Martineau
Intel