migration/rdma: Clean up two more harmless signed vs. unsigned issues

qemu_rdma_exchange_get_response() compares int parameter @expecting
with uint32_t head->type.  Actual arguments are non-negative
enumeration constants, RDMAControlHeader uint32_t member type, or
qemu_rdma_exchange_recv() int parameter expecting.  Actual arguments
for the latter are non-negative enumeration constants.  Change both
parameters to uint32_t.

In qio_channel_rdma_readv(), loop control variable @i is ssize_t, and
counts from 0 up to @niov, which is size_t.  Change @i to size_t.

While there, make qio_channel_rdma_readv() and
qio_channel_rdma_writev() more consistent: change the former's @done
to ssize_t, and delete the latter's useless initialization of @len.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20230928132019.2544702-8-armbru@redhat.com>

migration/rdma.c

@@ -1801,7 +1801,7 @@ static int qemu_rdma_post_recv_control(RDMAContext *rdma, int idx)
  * Block and wait for a RECV control channel message to arrive.
  */
 static int qemu_rdma_exchange_get_response(RDMAContext *rdma,
-                RDMAControlHeader *head, int expecting, int idx)
+                RDMAControlHeader *head, uint32_t expecting, int idx)
 {
     uint32_t byte_len;
     int ret = qemu_rdma_block_for_wrid(rdma, RDMA_WRID_RECV_CONTROL + idx,
@@ -1961,7 +1961,7 @@ static int qemu_rdma_exchange_send(RDMAContext *rdma, RDMAControlHeader *head,
  * control-channel message.
  */
 static int qemu_rdma_exchange_recv(RDMAContext *rdma, RDMAControlHeader *head,
-                                int expecting)
+                                   uint32_t expecting)
 {
     RDMAControlHeader ready = {
                                 .len = 0,
@@ -2784,8 +2784,7 @@ static ssize_t qio_channel_rdma_writev(QIOChannel *ioc,
     RDMAContext *rdma;
     int ret;
     ssize_t done = 0;
-    size_t i;
-    size_t len = 0;
+    size_t i, len;
 
     RCU_READ_LOCK_GUARD();
     rdma = qatomic_rcu_read(&rioc->rdmaout);
@@ -2870,8 +2869,8 @@ static ssize_t qio_channel_rdma_readv(QIOChannel *ioc,
     RDMAContext *rdma;
     RDMAControlHeader head;
     int ret = 0;
-    ssize_t i;
-    size_t done = 0, len;
+    ssize_t done = 0;
+    size_t i, len;
 
     RCU_READ_LOCK_GUARD();
     rdma = qatomic_rcu_read(&rioc->rdmain);