[PATCH net-next 08/10] mptcp: sched: split get_subflow interface into two

From: Matthieu Baerts (NGI0)
Date: Fri Feb 21 2025 - 10:49:05 EST


From: Geliang Tang <tanggeliang@xxxxxxxxxx>

get_retrans() interface of the burst packet scheduler invokes a sleeping
function mptcp_pm_subflow_chk_stale(), which calls __lock_sock_fast().
So get_retrans() interface should be set with BPF_F_SLEEPABLE flag in
BPF. But get_send() interface of this scheduler can't be set with
BPF_F_SLEEPABLE flag since it's invoked in ack_update_msk() under mptcp
data lock.

So this patch has to split get_subflow() interface of packet scheduer into
two interfaces: get_send() and get_retrans(). Then we can set get_retrans()
interface alone with BPF_F_SLEEPABLE flag.

Signed-off-by: Geliang Tang <tanggeliang@xxxxxxxxxx>
Reviewed-by: Mat Martineau <martineau@xxxxxxxxxx>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>
---
include/net/mptcp.h | 5 +++--
net/mptcp/sched.c | 35 ++++++++++++++++++++++++-----------
2 files changed, 27 insertions(+), 13 deletions(-)

diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 814b5f2e3ed5e3e474a2bac5e4cca5a89abcfe1c..2c85ca92bb1c39989ae08a74ff4ef9b42099e60d 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -103,13 +103,14 @@ struct mptcp_out_options {
#define MPTCP_SUBFLOWS_MAX 8

struct mptcp_sched_data {
- bool reinject;
u8 subflows;
struct mptcp_subflow_context *contexts[MPTCP_SUBFLOWS_MAX];
};

struct mptcp_sched_ops {
- int (*get_subflow)(struct mptcp_sock *msk,
+ int (*get_send)(struct mptcp_sock *msk,
+ struct mptcp_sched_data *data);
+ int (*get_retrans)(struct mptcp_sock *msk,
struct mptcp_sched_data *data);

char name[MPTCP_SCHED_NAME_MAX];
diff --git a/net/mptcp/sched.c b/net/mptcp/sched.c
index df7dbcfa3b71370cc4d7e4e4f16cc1e41a50dddf..94dc4b3ad82f6a462961ae5195b7eba2271d8275 100644
--- a/net/mptcp/sched.c
+++ b/net/mptcp/sched.c
@@ -16,13 +16,25 @@
static DEFINE_SPINLOCK(mptcp_sched_list_lock);
static LIST_HEAD(mptcp_sched_list);

-static int mptcp_sched_default_get_subflow(struct mptcp_sock *msk,
+static int mptcp_sched_default_get_send(struct mptcp_sock *msk,
+ struct mptcp_sched_data *data)
+{
+ struct sock *ssk;
+
+ ssk = mptcp_subflow_get_send(msk);
+ if (!ssk)
+ return -EINVAL;
+
+ mptcp_subflow_set_scheduled(mptcp_subflow_ctx(ssk), true);
+ return 0;
+}
+
+static int mptcp_sched_default_get_retrans(struct mptcp_sock *msk,
struct mptcp_sched_data *data)
{
struct sock *ssk;

- ssk = data->reinject ? mptcp_subflow_get_retrans(msk) :
- mptcp_subflow_get_send(msk);
+ ssk = mptcp_subflow_get_retrans(msk);
if (!ssk)
return -EINVAL;

@@ -31,7 +43,8 @@ static int mptcp_sched_default_get_subflow(struct mptcp_sock *msk,
}

static struct mptcp_sched_ops mptcp_sched_default = {
- .get_subflow = mptcp_sched_default_get_subflow,
+ .get_send = mptcp_sched_default_get_send,
+ .get_retrans = mptcp_sched_default_get_retrans,
.name = "default",
.owner = THIS_MODULE,
};
@@ -73,7 +86,7 @@ void mptcp_get_available_schedulers(char *buf, size_t maxlen)

int mptcp_register_scheduler(struct mptcp_sched_ops *sched)
{
- if (!sched->get_subflow)
+ if (!sched->get_send)
return -EINVAL;

spin_lock(&mptcp_sched_list_lock);
@@ -164,10 +177,9 @@ int mptcp_sched_get_send(struct mptcp_sock *msk)
return 0;
}

- data.reinject = false;
if (msk->sched == &mptcp_sched_default || !msk->sched)
- return mptcp_sched_default_get_subflow(msk, &data);
- return msk->sched->get_subflow(msk, &data);
+ return mptcp_sched_default_get_send(msk, &data);
+ return msk->sched->get_send(msk, &data);
}

int mptcp_sched_get_retrans(struct mptcp_sock *msk)
@@ -186,8 +198,9 @@ int mptcp_sched_get_retrans(struct mptcp_sock *msk)
return 0;
}

- data.reinject = true;
if (msk->sched == &mptcp_sched_default || !msk->sched)
- return mptcp_sched_default_get_subflow(msk, &data);
- return msk->sched->get_subflow(msk, &data);
+ return mptcp_sched_default_get_retrans(msk, &data);
+ if (msk->sched->get_retrans)
+ return msk->sched->get_retrans(msk, &data);
+ return msk->sched->get_send(msk, &data);
}

--
2.47.1