[SCTP] Break out sctp_assoc_valid() from sctp_id2assoc().

sctp_id2assoc() was trying to do too many things.  Break out, so
sctp_assoc_bh_rcv() can just find out whether the assoc is valid.

net/sctp/associola.c

@@ -793,6 +793,26 @@ struct sctp_transport *sctp_assoc_is_match(struct sctp_association *asoc,
 	return transport;
 }
 
+/*  Is this a live association structure. */
+int sctp_assoc_valid(struct sock *sk, struct sctp_association *asoc)
+{
+
+	/* First, verify that this is a kernel address. */
+	if (!sctp_is_valid_kaddr((unsigned long) asoc))
+		return 0;
+
+	/* Verify that this _is_ an sctp_association
+	 * data structure and if so, that the socket matches.
+	 */
+	if (SCTP_ASSOC_EYECATCHER != asoc->eyecatcher)
+		return 0;
+	if (asoc->base.sk != sk)
+		return 0;
+
+	/* The association is valid. */
+	return 1;
+}
+
 /* Do delayed input processing.  This is scheduled by sctp_rcv(). */
 static void sctp_assoc_bh_rcv(struct sctp_association *asoc)
 {
@@ -801,7 +821,6 @@ static void sctp_assoc_bh_rcv(struct sctp_association *asoc)
 	struct sock *sk;
 	struct sctp_inq *inqueue;
 	int state, subtype;
-	sctp_assoc_t associd = sctp_assoc2id(asoc);
 	int error = 0;
 
 	/* The association should be held so we should be safe. */
@@ -831,7 +850,7 @@ static void sctp_assoc_bh_rcv(struct sctp_association *asoc)
 		/* Check to see if the association is freed in response to
 		 * the incoming chunk.  If so, get out of the while loop.
 		 */
-		if (!sctp_id2assoc(sk, associd))
+		if (!sctp_assoc_valid(sk, asoc))
 			break;
 
 		/* If there is an error on chunk, discard this packet. */

net/sctp/socket.c

@@ -101,6 +101,9 @@ static char *sctp_hmac_alg = SCTP_COOKIE_HMAC_ALG;
 
 extern kmem_cache_t *sctp_bucket_cachep;
 
+
+extern int sctp_assoc_valid(struct sock *sk, struct sctp_association *asoc);
+
 /* Look up the association by its id.  If this is not a UDP-style
  * socket, the ID field is always ignored.
  */
@@ -124,18 +127,10 @@ struct sctp_association *sctp_id2assoc(struct sock *sk, sctp_assoc_t id)
 		return asoc;
 	}
 
-	/* First, verify that this is a kernel address. */
-	if (sctp_is_valid_kaddr((unsigned long) id)) {
-		struct sctp_association *temp;
-
-		/* Verify that this _is_ an sctp_association
-		 * data structure and if so, that the socket matches.
-		 */
-		temp = (struct sctp_association *)id;
-		if ((SCTP_ASSOC_EYECATCHER == temp->eyecatcher) &&
-		    (temp->base.sk == sk))
-			asoc = temp;
-	}
+	/* Otherwise this is a UDP-style socket. */
+	asoc = (struct sctp_association *)id;
+	if (!sctp_assoc_valid(sk, asoc))
+		return NULL;
 
 	return asoc;
 }