sctp: fix some type cast warnings introduced since very beginning

These warnings were found by running 'make C=2 M=net/sctp/'.
They are there since very beginning.

Note after this patch, there still one warning left in
sctp_outq_flush():
  sctp_chunk_fail(chunk, SCTP_ERROR_INV_STRM)

Since it has been moved to sctp_stream_outq_migrate on net-next,
to avoid the extra job when merging net-next to net, I will post
the fix for it after the merging is done.
Reported-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NXin Long <lucien.xin@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/sctp.h

@@ -231,7 +231,7 @@ struct sctp_datahdr {
 	__be32 tsn;
 	__be16 stream;
 	__be16 ssn;
-	__be32 ppid;
+	__u32 ppid;
 	__u8  payload[0];
 };
 

include/uapi/linux/sctp.h

@@ -376,7 +376,7 @@ struct sctp_remote_error {
 	__u16 sre_type;
 	__u16 sre_flags;
 	__u32 sre_length;
-	__u16 sre_error;
+	__be16 sre_error;
 	sctp_assoc_t sre_assoc_id;
 	__u8 sre_data[0];
 };

net/sctp/ipv6.c

@@ -738,7 +738,7 @@ static int sctp_v6_skb_iif(const struct sk_buff *skb)
 /* Was this packet marked by Explicit Congestion Notification? */
 static int sctp_v6_is_ce(const struct sk_buff *skb)
 {
-	return *((__u32 *)(ipv6_hdr(skb))) & htonl(1 << 20);
+	return *((__u32 *)(ipv6_hdr(skb))) & (__force __u32)htonl(1 << 20);
 }
 
 /* Dump the v6 addr to the seq file. */

net/sctp/sm_make_chunk.c

@@ -2854,7 +2854,7 @@ struct sctp_chunk *sctp_make_asconf_update_ip(struct sctp_association *asoc,
 		addr_param_len = af->to_addr_param(addr, &addr_param);
 		param.param_hdr.type = flags;
 		param.param_hdr.length = htons(paramlen + addr_param_len);
-		param.crr_id = i;
+		param.crr_id = htonl(i);
 
 		sctp_addto_chunk(retval, paramlen, &param);
 		sctp_addto_chunk(retval, addr_param_len, &addr_param);
@@ -2867,7 +2867,7 @@ struct sctp_chunk *sctp_make_asconf_update_ip(struct sctp_association *asoc,
 		addr_param_len = af->to_addr_param(addr, &addr_param);
 		param.param_hdr.type = SCTP_PARAM_DEL_IP;
 		param.param_hdr.length = htons(paramlen + addr_param_len);
-		param.crr_id = i;
+		param.crr_id = htonl(i);
 
 		sctp_addto_chunk(retval, paramlen, &param);
 		sctp_addto_chunk(retval, addr_param_len, &addr_param);

net/sctp/sm_sideeffect.c

@@ -1607,12 +1607,12 @@ static int sctp_cmd_interpreter(enum sctp_event event_type,
 			break;
 
 		case SCTP_CMD_INIT_FAILED:
-			sctp_cmd_init_failed(commands, asoc, cmd->obj.err);
+			sctp_cmd_init_failed(commands, asoc, cmd->obj.u32);
 			break;
 
 		case SCTP_CMD_ASSOC_FAILED:
 			sctp_cmd_assoc_failed(commands, asoc, event_type,
-					      subtype, chunk, cmd->obj.err);
+					      subtype, chunk, cmd->obj.u32);
 			break;
 
 		case SCTP_CMD_INIT_COUNTER_INC: