migration: Change ram_dirty_bitmap_reload() retval to bool

Now we have a Error** passed into the return path thread stack, which is
even clearer than an int retval.  Change ram_dirty_bitmap_reload() and the
callers to use a bool instead to replace errnos.

Suggested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20231017202633.296756-5-peterx@redhat.com>

migration/migration.c

@@ -1971,29 +1971,29 @@ migrate_handle_rp_req_pages(MigrationState *ms, const char* rbname,
     ram_save_queue_pages(rbname, start, len, errp);
 }
 
-static int migrate_handle_rp_recv_bitmap(MigrationState *s, char *block_name,
-                                         Error **errp)
+static bool migrate_handle_rp_recv_bitmap(MigrationState *s, char *block_name,
+                                          Error **errp)
 {
     RAMBlock *block = qemu_ram_block_by_name(block_name);
 
     if (!block) {
         error_setg(errp, "MIG_RP_MSG_RECV_BITMAP has invalid block name '%s'",
                    block_name);
-        return -EINVAL;
+        return false;
     }
 
     /* Fetch the received bitmap and refresh the dirty bitmap */
     return ram_dirty_bitmap_reload(s, block, errp);
 }
 
-static int migrate_handle_rp_resume_ack(MigrationState *s,
-                                        uint32_t value, Error **errp)
+static bool migrate_handle_rp_resume_ack(MigrationState *s,
+                                         uint32_t value, Error **errp)
 {
     trace_source_return_path_thread_resume_ack(value);
 
     if (value != MIGRATION_RESUME_ACK_VALUE) {
         error_setg(errp, "illegal resume_ack value %"PRIu32, value);
-        return -1;
+        return false;
     }
 
     /* Now both sides are active. */
@@ -2003,7 +2003,7 @@ static int migrate_handle_rp_resume_ack(MigrationState *s,
     /* Notify send thread that time to continue send pages */
     migration_rp_kick(s);
 
-    return 0;
+    return true;
 }
 
 /*
@@ -2154,14 +2154,14 @@ static void *source_return_path_thread(void *opaque)
             }
             /* Format: len (1B) + idstr (<255B). This ends the idstr. */
             buf[buf[0] + 1] = '\0';
-            if (migrate_handle_rp_recv_bitmap(ms, (char *)(buf + 1), &err)) {
+            if (!migrate_handle_rp_recv_bitmap(ms, (char *)(buf + 1), &err)) {
                 goto out;
             }
             break;
 
         case MIG_RP_MSG_RESUME_ACK:
             tmp32 = ldl_be_p(buf);
-            if (migrate_handle_rp_resume_ack(ms, tmp32, &err)) {
+            if (!migrate_handle_rp_resume_ack(ms, tmp32, &err)) {
                 goto out;
             }
             break;

migration/ram.c

@@ -4113,10 +4113,11 @@ static int ram_dirty_bitmap_sync_all(MigrationState *s, RAMState *rs)
  * Read the received bitmap, revert it as the initial dirty bitmap.
  * This is only used when the postcopy migration is paused but wants
  * to resume from a middle point.
+ *
+ * Returns true if succeeded, false for errors.
  */
-int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *block, Error **errp)
+bool ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *block, Error **errp)
 {
-    int ret = -EINVAL;
     /* from_dst_file is always valid because we're within rp_thread */
     QEMUFile *file = s->rp_state.from_dst_file;
     g_autofree unsigned long *le_bitmap = NULL;
@@ -4130,7 +4131,7 @@ int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *block, Error **errp)
     if (s->state != MIGRATION_STATUS_POSTCOPY_RECOVER) {
         error_setg(errp, "Reload bitmap in incorrect state %s",
                    MigrationStatus_str(s->state));
-        return -EINVAL;
+        return false;
     }
 
     /*
@@ -4148,24 +4149,23 @@ int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *block, Error **errp)
     if (size != local_size) {
         error_setg(errp, "ramblock '%s' bitmap size mismatch (0x%"PRIx64
                    " != 0x%"PRIx64")", block->idstr, size, local_size);
-        return -EINVAL;
+        return false;
     }
 
     size = qemu_get_buffer(file, (uint8_t *)le_bitmap, local_size);
     end_mark = qemu_get_be64(file);
 
-    ret = qemu_file_get_error(file);
-    if (ret || size != local_size) {
-        error_setg(errp, "read bitmap failed for ramblock '%s': %d"
-                   " (size 0x%"PRIx64", got: 0x%"PRIx64")",
-                   block->idstr, ret, local_size, size);
-        return -EIO;
+    if (qemu_file_get_error(file) || size != local_size) {
+        error_setg(errp, "read bitmap failed for ramblock '%s': "
+                   "(size 0x%"PRIx64", got: 0x%"PRIx64")",
+                   block->idstr, local_size, size);
+        return false;
     }
 
     if (end_mark != RAMBLOCK_RECV_BITMAP_ENDING) {
         error_setg(errp, "ramblock '%s' end mark incorrect: 0x%"PRIx64,
                    block->idstr, end_mark);
-        return -EINVAL;
+        return false;
     }
 
     /*
@@ -4197,7 +4197,7 @@ int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *block, Error **errp)
      */
     migration_rp_kick(s);
 
-    return 0;
+    return true;
 }
 
 static int ram_resume_prepare(MigrationState *s, void *opaque)

migration/ram.h

@@ -71,7 +71,7 @@ void ramblock_recv_bitmap_set(RAMBlock *rb, void *host_addr);
 void ramblock_recv_bitmap_set_range(RAMBlock *rb, void *host_addr, size_t nr);
 int64_t ramblock_recv_bitmap_send(QEMUFile *file,
                                   const char *block_name);
-int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *rb, Error **errp);
+bool ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *rb, Error **errp);
 bool ramblock_page_is_discarded(RAMBlock *rb, ram_addr_t start);
 void postcopy_preempt_shutdown_file(MigrationState *s);
 void *postcopy_preempt_thread(void *opaque);