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![Xin Long](/assets/img/avatar_default.png)
With this refcnt added in sctp_stream_priorities, we don't need to
traverse all streams to check if the prio is used by other streams
when freeing one stream's prio in sctp_sched_prio_free_sid(). This
can avoid a nested loop (up to 65535 * 65535), which may cause a
stuck as Ying reported:
watchdog: BUG: soft lockup - CPU#23 stuck for 26s! [ksoftirqd/23:136]
Call Trace:
<TASK>
sctp_sched_prio_free_sid+0xab/0x100 [sctp]
sctp_stream_free_ext+0x64/0xa0 [sctp]
sctp_stream_free+0x31/0x50 [sctp]
sctp_association_free+0xa5/0x200 [sctp]
Note that it doesn't need to use refcount_t type for this counter,
as its accessing is always protected under the sock lock.
v1->v2:
- add a check in sctp_sched_prio_set to avoid the possible prio_head
refcnt overflow.
Fixes: 9ed7bfc795
("sctp: fix memory leak in sctp_stream_outq_migrate()")
Reported-by: Ying Xu <yinxu@redhat.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Link: https://lore.kernel.org/r/825eb0c905cb864991eba335f4a2b780e543f06b.1677085641.git.lucien.xin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
319 lines
7.9 KiB
C
319 lines
7.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* SCTP kernel implementation
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* (C) Copyright Red Hat Inc. 2017
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*
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* This file is part of the SCTP kernel implementation
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*
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* These functions manipulate sctp stream queue/scheduling.
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*
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* Please send any bug reports or fixes you make to the
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* email addresched(es):
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* lksctp developers <linux-sctp@vger.kernel.org>
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*
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* Written or modified by:
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* Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
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*/
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#include <linux/list.h>
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#include <net/sctp/sctp.h>
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#include <net/sctp/sm.h>
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#include <net/sctp/stream_sched.h>
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/* Priority handling
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* RFC DRAFT ndata section 3.4
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*/
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static void sctp_sched_prio_unsched_all(struct sctp_stream *stream);
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static struct sctp_stream_priorities *sctp_sched_prio_head_get(struct sctp_stream_priorities *p)
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{
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p->users++;
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return p;
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}
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static void sctp_sched_prio_head_put(struct sctp_stream_priorities *p)
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{
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if (p && --p->users == 0)
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kfree(p);
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}
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static struct sctp_stream_priorities *sctp_sched_prio_new_head(
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struct sctp_stream *stream, int prio, gfp_t gfp)
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{
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struct sctp_stream_priorities *p;
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p = kmalloc(sizeof(*p), gfp);
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if (!p)
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return NULL;
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INIT_LIST_HEAD(&p->prio_sched);
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INIT_LIST_HEAD(&p->active);
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p->next = NULL;
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p->prio = prio;
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p->users = 1;
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return p;
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}
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static struct sctp_stream_priorities *sctp_sched_prio_get_head(
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struct sctp_stream *stream, int prio, gfp_t gfp)
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{
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struct sctp_stream_priorities *p;
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int i;
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/* Look into scheduled priorities first, as they are sorted and
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* we can find it fast IF it's scheduled.
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*/
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list_for_each_entry(p, &stream->prio_list, prio_sched) {
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if (p->prio == prio)
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return sctp_sched_prio_head_get(p);
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if (p->prio > prio)
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break;
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}
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/* No luck. So we search on all streams now. */
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for (i = 0; i < stream->outcnt; i++) {
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if (!SCTP_SO(stream, i)->ext)
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continue;
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p = SCTP_SO(stream, i)->ext->prio_head;
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if (!p)
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/* Means all other streams won't be initialized
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* as well.
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*/
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break;
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if (p->prio == prio)
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return sctp_sched_prio_head_get(p);
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}
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/* If not even there, allocate a new one. */
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return sctp_sched_prio_new_head(stream, prio, gfp);
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}
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static void sctp_sched_prio_next_stream(struct sctp_stream_priorities *p)
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{
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struct list_head *pos;
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pos = p->next->prio_list.next;
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if (pos == &p->active)
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pos = pos->next;
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p->next = list_entry(pos, struct sctp_stream_out_ext, prio_list);
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}
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static bool sctp_sched_prio_unsched(struct sctp_stream_out_ext *soute)
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{
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bool scheduled = false;
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if (!list_empty(&soute->prio_list)) {
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struct sctp_stream_priorities *prio_head = soute->prio_head;
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/* Scheduled */
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scheduled = true;
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if (prio_head->next == soute)
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/* Try to move to the next stream */
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sctp_sched_prio_next_stream(prio_head);
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list_del_init(&soute->prio_list);
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/* Also unsched the priority if this was the last stream */
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if (list_empty(&prio_head->active)) {
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list_del_init(&prio_head->prio_sched);
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/* If there is no stream left, clear next */
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prio_head->next = NULL;
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}
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}
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return scheduled;
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}
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static void sctp_sched_prio_sched(struct sctp_stream *stream,
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struct sctp_stream_out_ext *soute)
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{
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struct sctp_stream_priorities *prio, *prio_head;
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prio_head = soute->prio_head;
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/* Nothing to do if already scheduled */
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if (!list_empty(&soute->prio_list))
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return;
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/* Schedule the stream. If there is a next, we schedule the new
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* one before it, so it's the last in round robin order.
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* If there isn't, we also have to schedule the priority.
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*/
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if (prio_head->next) {
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list_add(&soute->prio_list, prio_head->next->prio_list.prev);
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return;
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}
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list_add(&soute->prio_list, &prio_head->active);
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prio_head->next = soute;
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list_for_each_entry(prio, &stream->prio_list, prio_sched) {
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if (prio->prio > prio_head->prio) {
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list_add(&prio_head->prio_sched, prio->prio_sched.prev);
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return;
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}
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}
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list_add_tail(&prio_head->prio_sched, &stream->prio_list);
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}
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static int sctp_sched_prio_set(struct sctp_stream *stream, __u16 sid,
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__u16 prio, gfp_t gfp)
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{
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struct sctp_stream_out *sout = SCTP_SO(stream, sid);
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struct sctp_stream_out_ext *soute = sout->ext;
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struct sctp_stream_priorities *prio_head, *old;
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bool reschedule = false;
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old = soute->prio_head;
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if (old && old->prio == prio)
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return 0;
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prio_head = sctp_sched_prio_get_head(stream, prio, gfp);
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if (!prio_head)
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return -ENOMEM;
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reschedule = sctp_sched_prio_unsched(soute);
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soute->prio_head = prio_head;
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if (reschedule)
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sctp_sched_prio_sched(stream, soute);
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sctp_sched_prio_head_put(old);
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return 0;
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}
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static int sctp_sched_prio_get(struct sctp_stream *stream, __u16 sid,
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__u16 *value)
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{
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*value = SCTP_SO(stream, sid)->ext->prio_head->prio;
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return 0;
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}
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static int sctp_sched_prio_init(struct sctp_stream *stream)
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{
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INIT_LIST_HEAD(&stream->prio_list);
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return 0;
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}
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static int sctp_sched_prio_init_sid(struct sctp_stream *stream, __u16 sid,
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gfp_t gfp)
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{
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INIT_LIST_HEAD(&SCTP_SO(stream, sid)->ext->prio_list);
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return sctp_sched_prio_set(stream, sid, 0, gfp);
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}
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static void sctp_sched_prio_free_sid(struct sctp_stream *stream, __u16 sid)
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{
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sctp_sched_prio_head_put(SCTP_SO(stream, sid)->ext->prio_head);
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SCTP_SO(stream, sid)->ext->prio_head = NULL;
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}
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static void sctp_sched_prio_enqueue(struct sctp_outq *q,
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struct sctp_datamsg *msg)
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{
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struct sctp_stream *stream;
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struct sctp_chunk *ch;
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__u16 sid;
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ch = list_first_entry(&msg->chunks, struct sctp_chunk, frag_list);
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sid = sctp_chunk_stream_no(ch);
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stream = &q->asoc->stream;
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sctp_sched_prio_sched(stream, SCTP_SO(stream, sid)->ext);
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}
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static struct sctp_chunk *sctp_sched_prio_dequeue(struct sctp_outq *q)
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{
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struct sctp_stream *stream = &q->asoc->stream;
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struct sctp_stream_priorities *prio;
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struct sctp_stream_out_ext *soute;
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struct sctp_chunk *ch = NULL;
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/* Bail out quickly if queue is empty */
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if (list_empty(&q->out_chunk_list))
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goto out;
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/* Find which chunk is next. It's easy, it's either the current
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* one or the first chunk on the next active stream.
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*/
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if (stream->out_curr) {
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soute = stream->out_curr->ext;
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} else {
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prio = list_entry(stream->prio_list.next,
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struct sctp_stream_priorities, prio_sched);
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soute = prio->next;
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}
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ch = list_entry(soute->outq.next, struct sctp_chunk, stream_list);
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sctp_sched_dequeue_common(q, ch);
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out:
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return ch;
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}
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static void sctp_sched_prio_dequeue_done(struct sctp_outq *q,
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struct sctp_chunk *ch)
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{
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struct sctp_stream_priorities *prio;
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struct sctp_stream_out_ext *soute;
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__u16 sid;
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/* Last chunk on that msg, move to the next stream on
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* this priority.
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*/
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sid = sctp_chunk_stream_no(ch);
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soute = SCTP_SO(&q->asoc->stream, sid)->ext;
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prio = soute->prio_head;
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sctp_sched_prio_next_stream(prio);
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if (list_empty(&soute->outq))
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sctp_sched_prio_unsched(soute);
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}
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static void sctp_sched_prio_sched_all(struct sctp_stream *stream)
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{
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struct sctp_association *asoc;
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struct sctp_stream_out *sout;
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struct sctp_chunk *ch;
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asoc = container_of(stream, struct sctp_association, stream);
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list_for_each_entry(ch, &asoc->outqueue.out_chunk_list, list) {
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__u16 sid;
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sid = sctp_chunk_stream_no(ch);
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sout = SCTP_SO(stream, sid);
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if (sout->ext)
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sctp_sched_prio_sched(stream, sout->ext);
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}
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}
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static void sctp_sched_prio_unsched_all(struct sctp_stream *stream)
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{
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struct sctp_stream_priorities *p, *tmp;
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struct sctp_stream_out_ext *soute, *souttmp;
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list_for_each_entry_safe(p, tmp, &stream->prio_list, prio_sched)
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list_for_each_entry_safe(soute, souttmp, &p->active, prio_list)
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sctp_sched_prio_unsched(soute);
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}
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static struct sctp_sched_ops sctp_sched_prio = {
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.set = sctp_sched_prio_set,
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.get = sctp_sched_prio_get,
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.init = sctp_sched_prio_init,
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.init_sid = sctp_sched_prio_init_sid,
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.free_sid = sctp_sched_prio_free_sid,
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.enqueue = sctp_sched_prio_enqueue,
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.dequeue = sctp_sched_prio_dequeue,
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.dequeue_done = sctp_sched_prio_dequeue_done,
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.sched_all = sctp_sched_prio_sched_all,
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.unsched_all = sctp_sched_prio_unsched_all,
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};
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void sctp_sched_ops_prio_init(void)
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{
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sctp_sched_ops_register(SCTP_SS_PRIO, &sctp_sched_prio);
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}
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