sctp: delete free member from struct sctp_sched_ops

After commit 9ed7bfc79542 ("sctp: fix memory leak in
sctp_stream_outq_migrate()"), sctp_sched_set_sched() is the only
place calling sched->free(), and it can actually be replaced by
sched->free_sid() on each stream, and yet there's already a loop
to traverse all streams in sctp_sched_set_sched().

This patch adds a function sctp_sched_free_sched() where it calls
sched->free_sid() for each stream to replace sched->free() calls
in sctp_sched_set_sched() and then deletes the unused free member
from struct sctp_sched_ops.

Signed-off-by: Xin Long <[e-mail]>
Acked-by: Marcelo Ricardo Leitner <[e-mail]>
Link: https://lore.kernel.org/r/e1[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

include/net/sctp/stream_sched.h

···
 	int (*init_sid)(struct sctp_stream *stream, __u16 sid, gfp_t gfp);
 	/* free a stream */
 	void (*free_sid)(struct sctp_stream *stream, __u16 sid);
-	/* Frees the entire thing */
-	void (*free)(struct sctp_stream *stream);
 
 	/* Enqueue a chunk */
 	void (*enqueue)(struct sctp_outq *q, struct sctp_datamsg *msg);

net/sctp/stream_sched.c

···
 {
 }
 
-static void sctp_sched_fcfs_free(struct sctp_stream *stream)
-{
-}
-
 static void sctp_sched_fcfs_enqueue(struct sctp_outq *q,
 				    struct sctp_datamsg *msg)
 {
···
 	.init = sctp_sched_fcfs_init,
 	.init_sid = sctp_sched_fcfs_init_sid,
 	.free_sid = sctp_sched_fcfs_free_sid,
-	.free = sctp_sched_fcfs_free,
 	.enqueue = sctp_sched_fcfs_enqueue,
 	.dequeue = sctp_sched_fcfs_dequeue,
 	.dequeue_done = sctp_sched_fcfs_dequeue_done,
···
 	sctp_sched_ops_rr_init();
 }
 
+static void sctp_sched_free_sched(struct sctp_stream *stream)
+{
+	struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream);
+	struct sctp_stream_out_ext *soute;
+	int i;
+
+	sched->unsched_all(stream);
+	for (i = 0; i < stream->outcnt; i++) {
+		soute = SCTP_SO(stream, i)->ext;
+		if (!soute)
+			continue;
+		sched->free_sid(stream, i);
+		/* Give the next scheduler a clean slate. */
+		memset_after(soute, 0, outq);
+	}
+}
+
 int sctp_sched_set_sched(struct sctp_association *asoc,
 			 enum sctp_sched_type sched)
 {
···
 	if (sched > SCTP_SS_MAX)
 		return -EINVAL;
 
-	if (old) {
-		old->free(&asoc->stream);
-
-		/* Give the next scheduler a clean slate. */
-		for (i = 0; i < asoc->stream.outcnt; i++) {
-			struct sctp_stream_out_ext *ext = SCTP_SO(&asoc->stream, i)->ext;
-
-			if (!ext)
-				continue;
-			memset_after(ext, 0, outq);
-		}
-	}
+	if (old)
+		sctp_sched_free_sched(&asoc->stream);
 
 	asoc->outqueue.sched = n;
 	n->init(&asoc->stream);
···
 	return ret;
 
 err:
-	n->free(&asoc->stream);
+	sctp_sched_free_sched(&asoc->stream);
 	asoc->outqueue.sched = &sctp_sched_fcfs; /* Always safe */
 
 	return ret;

net/sctp/stream_sched_prio.c

···
 	kfree(prio);
 }
 
-static void sctp_sched_prio_free(struct sctp_stream *stream)
-{
-	struct sctp_stream_priorities *prio, *n;
-	LIST_HEAD(list);
-	int i;
-
-	/* As we don't keep a list of priorities, to avoid multiple
-	 * frees we have to do it in 3 steps:
-	 *   1. unsched everyone, so the lists are free to use in 2.
-	 *   2. build the list of the priorities
-	 *   3. free the list
-	 */
-	sctp_sched_prio_unsched_all(stream);
-	for (i = 0; i < stream->outcnt; i++) {
-		if (!SCTP_SO(stream, i)->ext)
-			continue;
-		prio = SCTP_SO(stream, i)->ext->prio_head;
-		if (prio && list_empty(&prio->prio_sched))
-			list_add(&prio->prio_sched, &list);
-	}
-	list_for_each_entry_safe(prio, n, &list, prio_sched) {
-		list_del_init(&prio->prio_sched);
-		kfree(prio);
-	}
-}
-
 static void sctp_sched_prio_enqueue(struct sctp_outq *q,
 				    struct sctp_datamsg *msg)
 {
···
 	.init = sctp_sched_prio_init,
 	.init_sid = sctp_sched_prio_init_sid,
 	.free_sid = sctp_sched_prio_free_sid,
-	.free = sctp_sched_prio_free,
 	.enqueue = sctp_sched_prio_enqueue,
 	.dequeue = sctp_sched_prio_dequeue,
 	.dequeue_done = sctp_sched_prio_dequeue_done,

net/sctp/stream_sched_rr.c

···
 {
 }
 
-static void sctp_sched_rr_free(struct sctp_stream *stream)
-{
-	sctp_sched_rr_unsched_all(stream);
-}
-
 static void sctp_sched_rr_enqueue(struct sctp_outq *q,
 				  struct sctp_datamsg *msg)
 {
···
 	.init = sctp_sched_rr_init,
 	.init_sid = sctp_sched_rr_init_sid,
 	.free_sid = sctp_sched_rr_free_sid,
-	.free = sctp_sched_rr_free,
 	.enqueue = sctp_sched_rr_enqueue,
 	.dequeue = sctp_sched_rr_dequeue,
 	.dequeue_done = sctp_sched_rr_dequeue_done,