migration: Don't use INT64_MAX for unlimited rate

Define and use RATE_LIMIT_DISABLED instead.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Message-Id: <20230515195709.63843-2-quintela@redhat.com>

migration/migration-stats.h

@@ -15,6 +15,12 @@
 
 #include "qemu/stats64.h"
 
+/*
+ * If rate_limit_max is 0, there is special code to remove the rate
+ * limit.
+ */
+#define RATE_LIMIT_DISABLED 0
+
 /*
  * These are the ram migration statistic counters.  It is loosely
  * based on MigrationStats.  We change to Stat64 any counter that

migration/migration.c

@@ -2304,7 +2304,7 @@ static void migration_completion(MigrationState *s)
                  * them if migration fails or is cancelled.
                  */
                 s->block_inactive = !migrate_colo();
-                qemu_file_set_rate_limit(s->to_dst_file, INT64_MAX);
+                qemu_file_set_rate_limit(s->to_dst_file, RATE_LIMIT_DISABLED);
                 ret = qemu_savevm_state_complete_precopy(s->to_dst_file, false,
                                                          s->block_inactive);
             }
@@ -3048,7 +3048,7 @@ static void *bg_migration_thread(void *opaque)
     rcu_register_thread();
     object_ref(OBJECT(s));
 
-    qemu_file_set_rate_limit(s->to_dst_file, INT64_MAX);
+    qemu_file_set_rate_limit(s->to_dst_file, RATE_LIMIT_DISABLED);
 
     setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST);
     /*

migration/qemu-file.c

@@ -27,6 +27,7 @@
 #include "qemu/error-report.h"
 #include "qemu/iov.h"
 #include "migration.h"
+#include "migration-stats.h"
 #include "qemu-file.h"
 #include "trace.h"
 #include "options.h"
@@ -732,7 +733,10 @@ int qemu_file_rate_limit(QEMUFile *f)
     if (qemu_file_get_error(f)) {
         return 1;
     }
-    if (f->rate_limit_max > 0 && f->rate_limit_used > f->rate_limit_max) {
+    if (f->rate_limit_max == RATE_LIMIT_DISABLED) {
+        return 0;
+    }
+    if (f->rate_limit_used > f->rate_limit_max) {
         return 1;
     }
     return 0;