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// 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);
static int mptcp_sched_default_get_subflow(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);
if (!ssk)
return -EINVAL;
mptcp_subflow_set_scheduled(mptcp_subflow_ctx(ssk), true);
return 0;
}
static struct mptcp_sched_ops mptcp_sched_default = {
.get_subflow = mptcp_sched_default_get_subflow,
.name = "default",
.owner = THIS_MODULE,
};
/* 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;
}
/* Build string with list of available scheduler values.
* Similar to tcp_get_available_congestion_control()
*/
void mptcp_get_available_schedulers(char *buf, size_t maxlen)
{
struct mptcp_sched_ops *sched;
size_t offs = 0;
rcu_read_lock();
spin_lock(&mptcp_sched_list_lock);
list_for_each_entry_rcu(sched, &mptcp_sched_list, list) {
offs += snprintf(buf + offs, maxlen - offs,
"%s%s",
offs == 0 ? "" : " ", sched->name);
if (WARN_ON_ONCE(offs >= maxlen))
break;
}
spin_unlock(&mptcp_sched_list_lock);
rcu_read_unlock();
}
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\n", sched->name);
return 0;
}
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);
}
int mptcp_init_sched(struct mptcp_sock *msk,
struct mptcp_sched_ops *sched)
{
if (!sched)
sched = &mptcp_sched_default;
if (!bpf_try_module_get(sched, sched->owner))
return -EBUSY;
msk->sched = sched;
if (msk->sched->init)
msk->sched->init(msk);
pr_debug("sched=%s\n", 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);
}
void mptcp_subflow_set_scheduled(struct mptcp_subflow_context *subflow,
bool scheduled)
{
WRITE_ONCE(subflow->scheduled, scheduled);
}
int mptcp_sched_get_send(struct mptcp_sock *msk)
{
struct mptcp_subflow_context *subflow;
struct mptcp_sched_data data;
msk_owned_by_me(msk);
/* the following check is moved out of mptcp_subflow_get_send */
if (__mptcp_check_fallback(msk)) {
if (msk->first &&
__tcp_can_send(msk->first) &&
sk_stream_memory_free(msk->first)) {
mptcp_subflow_set_scheduled(mptcp_subflow_ctx(msk->first), true);
return 0;
}
return -EINVAL;
}
mptcp_for_each_subflow(msk, subflow) {
if (READ_ONCE(subflow->scheduled))
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);
}
int mptcp_sched_get_retrans(struct mptcp_sock *msk)
{
struct mptcp_subflow_context *subflow;
struct mptcp_sched_data data;
msk_owned_by_me(msk);
/* the following check is moved out of mptcp_subflow_get_retrans */
if (__mptcp_check_fallback(msk))
return -EINVAL;
mptcp_for_each_subflow(msk, subflow) {
if (READ_ONCE(subflow->scheduled))
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);
}
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