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Message-ID: <4C8E2AE2.9050309@hp.com>
Date: Mon, 13 Sep 2010 09:45:06 -0400
From: Vlad Yasevich <vladislav.yasevich@...com>
To: Yaogong Wang <ywang15@...u.edu>
CC: linux-sctp@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2 2/5] sctp: implement pluggable multistream scheduling
One small nit.
On 09/11/2010 09:12 PM, Yaogong Wang wrote:
> Implement the pluggable multistream scheduling framework.
> Provide the default first-come-first-serve (FCFS) algorithm.
>
> Signed-off-by: Yaogong Wang <ywang15@...u.edu>
> ---
> diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
> index 5027b83..d40c5cc 100644
> --- a/net/sctp/protocol.c
> +++ b/net/sctp/protocol.c
> @@ -1157,6 +1157,9 @@ SCTP_STATIC __init int sctp_init(void)
> sctp_max_instreams = SCTP_DEFAULT_INSTREAMS;
> sctp_max_outstreams = SCTP_DEFAULT_OUTSTREAMS;
>
> + /* Initialize default multistream scheduling algorithm to FCFS */
> + sctp_default_sched_ops = &sctp_fcfs;
> +
> /* Initialize handle used for association ids. */
> idr_init(&sctp_assocs_id);
>
> @@ -1304,6 +1307,11 @@ SCTP_STATIC __init int sctp_init(void)
> if (status)
> goto err_v6_add_protocol;
>
> + /* Add FCFS to sctp_sched_list */
> + status = sctp_register_sched(&sctp_fcfs);
> + if (status)
> + goto err_v6_add_protocol;
> +
This needs its own tag that will call sctp_v6_del_protocol().
-vlad
> status = 0;
> out:
> return status;
> @@ -1348,6 +1356,9 @@ SCTP_STATIC __exit void sctp_exit(void)
> * up all the remaining associations and all that memory.
> */
>
> + /* Unregister FCFS from sctp_sched_list */
> + sctp_unregister_sched(&sctp_fcfs);
> +
> /* Unregister with inet6/inet layers. */
> sctp_v6_del_protocol();
> sctp_v4_del_protocol();
> diff --git a/net/sctp/sched.c b/net/sctp/sched.c
> new file mode 100644
> index 0000000..3820e3f
> --- /dev/null
> +++ b/net/sctp/sched.c
> @@ -0,0 +1,177 @@
> +/*
> + * Plugable SCTP multistream scheduling support and
> + * the default first-come-first-serve (FCFS) algorithm
> + *
> + * Based on ideas from pluggable TCP congestion control
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/types.h>
> +#include <linux/list.h>
> +#include <net/sctp/sctp.h>
> +
> +static DEFINE_SPINLOCK(sctp_sched_list_lock);
> +static LIST_HEAD(sctp_sched_list);
> +
> +/* Simple linear search, don't expect many entries! */
> +static struct sctp_sched_ops *sctp_sched_find(const char *name)
> +{
> + struct sctp_sched_ops *e;
> +
> + list_for_each_entry_rcu(e, &sctp_sched_list, list) {
> + if (strcmp(e->name, name) == 0)
> + return e;
> + }
> +
> + return NULL;
> +}
> +
> +/*
> + * Attach new scheduling algorithm to the list
> + * of available options.
> + */
> +int sctp_register_sched(struct sctp_sched_ops *sched)
> +{
> + int ret = 0;
> +
> + /* algorithm must implement required ops */
> + if (!sched->init || !sched->release || !sched->is_empty
> + || !sched->enqueue_head_data || !sched->enqueue_tail_data
> + || !sched->dequeue_data) {
> + printk(KERN_ERR "SCTP %s does not implement required ops\n",
> + sched->name);
> + return -EINVAL;
> + }
> +
> + spin_lock(&sctp_sched_list_lock);
> + if (sctp_sched_find(sched->name)) {
> + printk(KERN_NOTICE "SCTP %s already registered\n", sched->name);
> + ret = -EEXIST;
> + } else {
> + list_add_tail_rcu(&sched->list, &sctp_sched_list);
> + printk(KERN_INFO "SCTP %s registered\n", sched->name);
> + }
> + spin_unlock(&sctp_sched_list_lock);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(sctp_register_sched);
> +
> +/*
> + * Remove scheduling algorithm, called from
> + * the module's remove function. Module ref counts are used
> + * to ensure that this can't be done till all sockets using
> + * that method are closed.
> + */
> +void sctp_unregister_sched(struct sctp_sched_ops *sched)
> +{
> + spin_lock(&sctp_sched_list_lock);
> + list_del_rcu(&sched->list);
> + spin_unlock(&sctp_sched_list_lock);
> +}
> +EXPORT_SYMBOL_GPL(sctp_unregister_sched);
> +
> +/* Manage refcounts on socket close. */
> +void sctp_cleanup_sched(struct sock *sk)
> +{
> + module_put(sctp_sk(sk)->sched_ops->owner);
> +}
> +
> +/* Change scheduling algorithm for socket */
> +int sctp_set_sched(struct sock *sk, const char *name)
> +{
> + struct sctp_sock *sp = sctp_sk(sk);
> + struct sctp_sched_ops *sched;
> + int err = 0;
> +
> + rcu_read_lock();
> + sched = sctp_sched_find(name);
> +
> + /* no change asking for existing value */
> + if (sched == sp->sched_ops)
> + goto out;
> +
> +#ifdef CONFIG_MODULES
> + /* not found attempt to autoload module */
> + if (!sched && capable(CAP_NET_ADMIN)) {
> + rcu_read_unlock();
> + request_module("sctp_%s", name);
> + rcu_read_lock();
> + sched = sctp_sched_find(name);
> + }
> +#endif
> + if (!sched)
> + err = -ENOENT;
> +
> + else if (!try_module_get(sched->owner))
> + err = -EBUSY;
> +
> + else {
> + sctp_cleanup_sched(sk);
> + sp->sched_ops = sched;
> + }
> +out:
> + rcu_read_unlock();
> + return err;
> +}
> +
> +static int fcfs_init(struct sctp_outq *q, gfp_t gfp)
> +{
> + q->out_chunk_list = kmalloc(sizeof(struct list_head), gfp);
> + if (!q->out_chunk_list)
> + return -ENOMEM;
> + INIT_LIST_HEAD(q->out_chunk_list);
> +
> + return 0;
> +}
> +
> +static void fcfs_release(struct sctp_outq *q)
> +{
> + kfree(q->out_chunk_list);
> +}
> +
> +static void fcfs_enqueue_head_data(struct sctp_outq *q,
> + struct sctp_chunk *ch)
> +{
> + list_add(&ch->list, q->out_chunk_list);
> + q->out_qlen += ch->skb->len;
> + return;
> +}
> +
> +static void fcfs_enqueue_tail_data(struct sctp_outq *q, struct sctp_chunk *ch)
> +{
> + list_add_tail(&ch->list, q->out_chunk_list);
> + q->out_qlen += ch->skb->len;
> + return;
> +}
> +
> +static struct sctp_chunk *fcfs_dequeue_data(struct sctp_outq *q)
> +{
> + struct sctp_chunk *ch = NULL;
> +
> + if (!list_empty(q->out_chunk_list)) {
> + struct list_head *entry = q->out_chunk_list->next;
> +
> + ch = list_entry(entry, struct sctp_chunk, list);
> + list_del_init(entry);
> + q->out_qlen -= ch->skb->len;
> + }
> + return ch;
> +}
> +
> +static inline int fcfs_is_empty(struct sctp_outq *q)
> +{
> + return list_empty(q->out_chunk_list);
> +}
> +
> +struct sctp_sched_ops sctp_fcfs = {
> + .name = "fcfs",
> + .owner = THIS_MODULE,
> + .init = fcfs_init,
> + .release = fcfs_release,
> + .enqueue_head_data = fcfs_enqueue_head_data,
> + .enqueue_tail_data = fcfs_enqueue_tail_data,
> + .dequeue_data = fcfs_dequeue_data,
> + .is_empty = fcfs_is_empty,
> +};
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index ca44917..7d461be 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -3644,6 +3644,9 @@ SCTP_STATIC int sctp_init_sock(struct sock *sk)
> sp->initmsg.sinit_max_attempts = sctp_max_retrans_init;
> sp->initmsg.sinit_max_init_timeo = sctp_rto_max;
>
> + /* Initialize default multistream scheduling algorithm */
> + sp->sched_ops = sctp_default_sched_ops;
> +
> /* Initialize default RTO related parameters. These parameters can
> * be modified for with the SCTP_RTOINFO socket option.
> */
--
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