migration/rdma: Plug memory leaks in qemu_rdma_registration_stop()

qemu_rdma_registration_stop() uses the ERROR() macro to create, report
to stderr, and store an Error object.  The stored Error object is
never used, and its memory is leaked.

Even where ERROR() doesn't leak, it is ill-advised.  The whole point
of passing an Error to the caller is letting the caller handle the
error.  Error handling may report to stderr, to somewhere else, or not
at all.  Also reporting in the callee mixes up concerns that should be
kept separate.  Since I don't know what reporting to stderr is
supposed to accomplish, I'm not touching it.

Commit 2a1bc8b "migration/rdma: rdma_accept_incoming_migration fix
error handling" plugged the same leak in
rdma_accept_incoming_migration().

Plug the memory leak the same way: keep the report part, delete the
store part.

The report part uses fprintf().  If it's truly an error, it should use
error_report() instead.  But I don't know, so I leave it alone, just
like commit 2a1bc8b did.

Fixes: 2da776d
Cc: Dr. David Alan Gilbert <[email protected]>
Cc: Juan Quintela <[email protected]>
Signed-off-by: Markus Armbruster <[email protected]>
Message-Id: <[email protected]>
Reviewed-by: Dr. David Alan Gilbert <[email protected]>

Author: Markus Armbruster

migration/rdma.c

@@ -3787,7 +3787,6 @@ static int qemu_rdma_registration_start(QEMUFile *f, void *opaque,
 static int qemu_rdma_registration_stop(QEMUFile *f, void *opaque,
                                        uint64_t flags, void *data)
 {
-    Error *local_err = NULL, **errp = &local_err;
     QIOChannelRDMA *rioc = QIO_CHANNEL_RDMA(opaque);
     RDMAContext *rdma;
     RDMAControlHeader head = { .len = 0, .repeat = 1 };
@@ -3832,7 +3831,7 @@ static int qemu_rdma_registration_stop(QEMUFile *f, void *opaque,
                     &reg_result_idx, rdma->pin_all ?
                     qemu_rdma_reg_whole_ram_blocks : NULL);
         if (ret < 0) {
-            ERROR(errp, "receiving remote info!");
+            fprintf(stderr, "receiving remote info!");
             return ret;
         }
 
@@ -3851,10 +3850,10 @@ static int qemu_rdma_registration_stop(QEMUFile *f, void *opaque,
          */
 
         if (local->nb_blocks != nb_dest_blocks) {
-            ERROR(errp, "ram blocks mismatch (Number of blocks %d vs %d) "
-                        "Your QEMU command line parameters are probably "
-                        "not identical on both the source and destination.",
-                        local->nb_blocks, nb_dest_blocks);
+            fprintf(stderr, "ram blocks mismatch (Number of blocks %d vs %d) "
+                    "Your QEMU command line parameters are probably "
+                    "not identical on both the source and destination.",
+                    local->nb_blocks, nb_dest_blocks);
             rdma->error_state = -EINVAL;
             return -EINVAL;
         }
@@ -3867,10 +3866,10 @@ static int qemu_rdma_registration_stop(QEMUFile *f, void *opaque,
 
             /* We require that the blocks are in the same order */
             if (rdma->dest_blocks[i].length != local->block[i].length) {
-                ERROR(errp, "Block %s/%d has a different length %" PRIu64
-                            "vs %" PRIu64, local->block[i].block_name, i,
-                            local->block[i].length,
-                            rdma->dest_blocks[i].length);
+                fprintf(stderr, "Block %s/%d has a different length %" PRIu64
+                        "vs %" PRIu64, local->block[i].block_name, i,
+                        local->block[i].length,
+                        rdma->dest_blocks[i].length);
                 rdma->error_state = -EINVAL;
                 return -EINVAL;
             }