sctp: convert to genradix

This also makes sctp_stream_alloc_(out|in) saner, in that they no longer
allocate new flex_arrays/genradixes, they just preallocate more
elements.

This code does however have a suspicious lack of locking.

Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Kent Overstreet <[e-mail]>
Cc: Vlad Yasevich <[e-mail]>
Cc: Neil Horman <[e-mail]>
Cc: Marcelo Ricardo Leitner <[e-mail]>
Cc: Alexey Dobriyan <[e-mail]>
Cc: Al Viro <[e-mail]>
Cc: Dave Hansen <[e-mail]>
Cc: Eric Paris <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Cc: Paul Moore <[e-mail]>
Cc: Pravin B Shelar <[e-mail]>
Cc: Shaohua Li <[e-mail]>
Cc: Stephen Smalley <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/net/sctp/structs.h

···
 #define __sctp_structs_h__
 
 #include <linux/ktime.h>
+#include <linux/generic-radix-tree.h>
 #include <linux/rhashtable-types.h>
 #include <linux/socket.h>	/* linux/in.h needs this!!    */
 #include <linux/in.h>		/* We get struct sockaddr_in. */
···
 #include <linux/atomic.h>		/* This gets us atomic counters.  */
 #include <linux/skbuff.h>	/* We need sk_buff_head. */
 #include <linux/workqueue.h>	/* We need tq_struct.	 */
-#include <linux/flex_array.h>	/* We need flex_array.   */
 #include <linux/sctp.h>		/* We need sctp* header structs.  */
 #include <net/sctp/auth.h>	/* We need auth specific structs */
 #include <net/ip.h>		/* For inet_skb_parm */
···
 };
 
 struct sctp_stream {
-	struct flex_array *out;
-	struct flex_array *in;
+	GENRADIX(struct sctp_stream_out) out;
+	GENRADIX(struct sctp_stream_in)	in;
+
 	__u16 outcnt;
 	__u16 incnt;
 	/* Current stream being sent, if any */
···
 };
 
 static inline struct sctp_stream_out *sctp_stream_out(
-	const struct sctp_stream *stream,
+	struct sctp_stream *stream,
 	__u16 sid)
 {
-	return flex_array_get(stream->out, sid);
+	return genradix_ptr(&stream->out, sid);
 }
 
 static inline struct sctp_stream_in *sctp_stream_in(
-	const struct sctp_stream *stream,
+	struct sctp_stream *stream,
 	__u16 sid)
 {
-	return flex_array_get(stream->in, sid);
+	return genradix_ptr(&stream->in, sid);
 }
 
 #define SCTP_SO(s, i) sctp_stream_out((s), (i))

net/sctp/stream.c

···
 #include <net/sctp/sm.h>
 #include <net/sctp/stream_sched.h>
 
-static struct flex_array *fa_alloc(size_t elem_size, size_t elem_count,
-				   gfp_t gfp)
-{
-	struct flex_array *result;
-	int err;
-
-	result = flex_array_alloc(elem_size, elem_count, gfp);
-	if (result) {
-		err = flex_array_prealloc(result, 0, elem_count, gfp);
-		if (err) {
-			flex_array_free(result);
-			result = NULL;
-		}
-	}
-
-	return result;
-}
-
-static void fa_free(struct flex_array *fa)
-{
-	if (fa)
-		flex_array_free(fa);
-}
-
-static void fa_copy(struct flex_array *fa, struct flex_array *from,
-		    size_t index, size_t count)
-{
-	void *elem;
-
-	while (count--) {
-		elem = flex_array_get(from, index);
-		flex_array_put(fa, index, elem, 0);
-		index++;
-	}
-}
-
-static void fa_zero(struct flex_array *fa, size_t index, size_t count)
-{
-	void *elem;
-
-	while (count--) {
-		elem = flex_array_get(fa, index);
-		memset(elem, 0, fa->element_size);
-		index++;
-	}
-}
-
-static size_t fa_index(struct flex_array *fa, void *elem, size_t count)
-{
-	size_t index = 0;
-
-	while (count--) {
-		if (elem == flex_array_get(fa, index))
-			break;
-		index++;
-	}
-
-	return index;
-}
-
 /* Migrates chunks from stream queues to new stream queues if needed,
  * but not across associations. Also, removes those chunks to streams
  * higher than the new max.
···
 static int sctp_stream_alloc_out(struct sctp_stream *stream, __u16 outcnt,
 				 gfp_t gfp)
 {
-	struct flex_array *out;
-	size_t elem_size = sizeof(struct sctp_stream_out);
+	int ret;
 
-	out = fa_alloc(elem_size, outcnt, gfp);
-	if (!out)
-		return -ENOMEM;
+	if (outcnt <= stream->outcnt)
+		return 0;
 
-	if (stream->out) {
-		fa_copy(out, stream->out, 0, min(outcnt, stream->outcnt));
-		if (stream->out_curr) {
-			size_t index = fa_index(stream->out, stream->out_curr,
-						stream->outcnt);
+	ret = genradix_prealloc(&stream->out, outcnt, gfp);
+	if (ret)
+		return ret;
 
-			BUG_ON(index == stream->outcnt);
-			stream->out_curr = flex_array_get(out, index);
-		}
-		fa_free(stream->out);
-	}
-
-	if (outcnt > stream->outcnt)
-		fa_zero(out, stream->outcnt, (outcnt - stream->outcnt));
-
-	stream->out = out;
-
+	stream->outcnt = outcnt;
 	return 0;
 }
 
 static int sctp_stream_alloc_in(struct sctp_stream *stream, __u16 incnt,
 				gfp_t gfp)
 {
-	struct flex_array *in;
-	size_t elem_size = sizeof(struct sctp_stream_in);
+	int ret;
 
-	in = fa_alloc(elem_size, incnt, gfp);
-	if (!in)
-		return -ENOMEM;
+	if (incnt <= stream->incnt)
+		return 0;
 
-	if (stream->in) {
-		fa_copy(in, stream->in, 0, min(incnt, stream->incnt));
-		fa_free(stream->in);
-	}
+	ret = genradix_prealloc(&stream->in, incnt, gfp);
+	if (ret)
+		return ret;
 
-	if (incnt > stream->incnt)
-		fa_zero(in, stream->incnt, (incnt - stream->incnt));
-
-	stream->in = in;
-
+	stream->incnt = incnt;
 	return 0;
 }
 
···
 	if (ret)
 		goto out;
 
-	stream->outcnt = outcnt;
 	for (i = 0; i < stream->outcnt; i++)
 		SCTP_SO(stream, i)->state = SCTP_STREAM_OPEN;
 
···
 	ret = sctp_stream_alloc_in(stream, incnt, gfp);
 	if (ret) {
 		sched->free(stream);
-		fa_free(stream->out);
-		stream->out = NULL;
+		genradix_free(&stream->out);
 		stream->outcnt = 0;
 		goto out;
 	}
-
-	stream->incnt = incnt;
 
 out:
 	return ret;
···
 	sched->free(stream);
 	for (i = 0; i < stream->outcnt; i++)
 		kfree(SCTP_SO(stream, i)->ext);
-	fa_free(stream->out);
-	fa_free(stream->in);
+	genradix_free(&stream->out);
+	genradix_free(&stream->in);
 }
 
 void sctp_stream_clear(struct sctp_stream *stream)
···
 
 	sched->sched_all(stream);
 
-	new->out = NULL;
-	new->in  = NULL;
+	new->out.tree.root = NULL;
+	new->in.tree.root  = NULL;
 	new->outcnt = 0;
 	new->incnt  = 0;
 }
···
 		asoc->strreset_chunk = NULL;
 		goto out;
 	}
-
-	stream->outcnt = outcnt;
 
 	asoc->strreset_outstanding = !!out + !!in;
 

net/sctp/stream_interleave.c

···
 
 static bool sctp_validate_data(struct sctp_chunk *chunk)
 {
-	const struct sctp_stream *stream;
+	struct sctp_stream *stream;
 	__u16 sid, ssn;
 
 	if (chunk->chunk_hdr->type != SCTP_CID_DATA)