migration/rdma: Return -1 instead of negative errno code

Several functions return negative errno codes on failure.  Callers
check for specific codes exactly never.  For some of the functions,
callers couldn't check even if they wanted to, because the functions
also return negative values that aren't errno codes, leaving readers
confused on what the function actually returns.

Clean up and simplify: return -1 instead of negative errno code.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Li Zhijian <lizhijian@fujitsu.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20230928132019.2544702-26-armbru@redhat.com>

migration/rdma.c

@@ -863,14 +863,14 @@ static int qemu_rdma_broken_ipv6_kernel(struct ibv_context *verbs, Error **errp)
                 } else {
                     error_setg_errno(errp, errno,
                                      "could not open RDMA device context");
-                    return -EINVAL;
+                    return -1;
                 }
             }
 
             if (ibv_query_port(verbs, 1, &port_attr)) {
                 ibv_close_device(verbs);
                 ERROR(errp, "Could not query initial IB port");
-                return -EINVAL;
+                return -1;
             }
 
             if (port_attr.link_layer == IBV_LINK_LAYER_INFINIBAND) {
@@ -895,7 +895,7 @@ static int qemu_rdma_broken_ipv6_kernel(struct ibv_context *verbs, Error **errp)
                 ERROR(errp, "You only have RoCE / iWARP devices in your systems"
                             " and your management software has specified '[::]'"
                             ", but IPv6 over RoCE / iWARP is not supported in Linux.");
-                return -ENONET;
+                return -1;
             }
         }
 
@@ -911,13 +911,13 @@ static int qemu_rdma_broken_ipv6_kernel(struct ibv_context *verbs, Error **errp)
     /* IB ports start with 1, not 0 */
     if (ibv_query_port(verbs, 1, &port_attr)) {
         ERROR(errp, "Could not query initial IB port");
-        return -EINVAL;
+        return -1;
     }
 
     if (port_attr.link_layer == IBV_LINK_LAYER_ETHERNET) {
         ERROR(errp, "Linux kernel's RoCE / iWARP does not support IPv6 "
                     "(but patches on linux-rdma in progress)");
-        return -ENONET;
+        return -1;
     }
 
 #endif
@@ -1425,7 +1425,7 @@ static int qemu_rdma_unregister_waiting(RDMAContext *rdma)
              * this series.
              */
             perror("unregistration chunk failed");
-            return -ret;
+            return -1;
         }
         rdma->total_registrations--;
 
@@ -1570,15 +1570,15 @@ static int qemu_rdma_wait_comp_channel(RDMAContext *rdma,
                     if (ret) {
                         error_report("failed to get cm event while wait "
                                      "completion channel");
-                        return -EPIPE;
+                        return -1;
                     }
 
                     error_report("receive cm event while wait comp channel,"
                                  "cm event is %d", cm_event->event);
                     if (cm_event->event == RDMA_CM_EVENT_DISCONNECTED ||
                         cm_event->event == RDMA_CM_EVENT_DEVICE_REMOVAL) {
                         rdma_ack_cm_event(cm_event);
-                        return -EPIPE;
+                        return -1;
                     }
                     rdma_ack_cm_event(cm_event);
                 }
@@ -1591,18 +1591,18 @@ static int qemu_rdma_wait_comp_channel(RDMAContext *rdma,
                       * I don't trust errno from qemu_poll_ns
                      */
                 error_report("%s: poll failed", __func__);
-                return -EPIPE;
+                return -1;
             }
 
             if (migrate_get_current()->state == MIGRATION_STATUS_CANCELLING) {
                 /* Bail out and let the cancellation happen */
-                return -EPIPE;
+                return -1;
             }
         }
     }
 
     if (rdma->received_error) {
-        return -EPIPE;
+        return -1;
     }
     return rdma->error_state;
 }
@@ -1772,7 +1772,7 @@ static int qemu_rdma_post_send_control(RDMAContext *rdma, uint8_t *buf,
 
     if (ret > 0) {
         error_report("Failed to use post IB SEND for control");
-        return -ret;
+        return -1;
     }
 
     ret = qemu_rdma_block_for_wrid(rdma, RDMA_WRID_SEND_CONTROL, NULL);
@@ -1841,15 +1841,15 @@ static int qemu_rdma_exchange_get_response(RDMAContext *rdma,
         if (head->type == RDMA_CONTROL_ERROR) {
             rdma->received_error = true;
         }
-        return -EIO;
+        return -1;
     }
     if (head->len > RDMA_CONTROL_MAX_BUFFER - sizeof(*head)) {
         error_report("too long length: %d", head->len);
-        return -EINVAL;
+        return -1;
     }
     if (sizeof(*head) + head->len != byte_len) {
         error_report("Malformed length: %d byte_len %d", head->len, byte_len);
-        return -EINVAL;
+        return -1;
     }
 
     return 0;
@@ -2115,7 +2115,7 @@ static int qemu_rdma_write_one(RDMAContext *rdma,
                                 (uint8_t *) &comp, NULL, NULL, NULL);
 
                 if (ret < 0) {
-                    return -EIO;
+                    return -1;
                 }
 
                 /*
@@ -2159,7 +2159,7 @@ static int qemu_rdma_write_one(RDMAContext *rdma,
                                                 &sge.lkey, NULL, chunk,
                                                 chunk_start, chunk_end)) {
                 error_report("cannot get lkey");
-                return -EINVAL;
+                return -1;
             }
 
             reg_result = (RDMARegisterResult *)
@@ -2178,7 +2178,7 @@ static int qemu_rdma_write_one(RDMAContext *rdma,
                                                 &sge.lkey, NULL, chunk,
                                                 chunk_start, chunk_end)) {
                 error_report("cannot get lkey!");
-                return -EINVAL;
+                return -1;
             }
         }
 
@@ -2190,7 +2190,7 @@ static int qemu_rdma_write_one(RDMAContext *rdma,
                                                      &sge.lkey, NULL, chunk,
                                                      chunk_start, chunk_end)) {
             error_report("cannot get lkey!");
-            return -EINVAL;
+            return -1;
         }
     }
 
@@ -2237,7 +2237,7 @@ static int qemu_rdma_write_one(RDMAContext *rdma,
          * in this series.
          */
         perror("rdma migration: post rdma write failed");
-        return -ret;
+        return -1;
     }
 
     set_bit(chunk, block->transit_bitmap);
@@ -2969,14 +2969,14 @@ static int qemu_rdma_drain_cq(RDMAContext *rdma)
     int ret;
 
     if (qemu_rdma_write_flush(rdma) < 0) {
-        return -EIO;
+        return -1;
     }
 
     while (rdma->nb_sent) {
         ret = qemu_rdma_block_for_wrid(rdma, RDMA_WRID_RDMA_WRITE, NULL);
         if (ret < 0) {
             error_report("rdma migration: complete polling error!");
-            return -EIO;
+            return -1;
         }
     }