throttle: Use throttle_config_init() to initialize ThrottleConfig

We can currently initialize ThrottleConfig by zeroing all its fields,
but this will change with the new fields to define the length of the
burst periods.

This patch introduces a new throttle_config_init() function and uses it
to replace all memset() calls that initialize ThrottleConfig directly.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

blockdev.c

@@ -387,7 +387,7 @@ static void extract_common_blockdev_options(QemuOpts *opts, int *bdrv_flags,
     }
 
     if (throttle_cfg) {
-        memset(throttle_cfg, 0, sizeof(*throttle_cfg));
+        throttle_config_init(throttle_cfg);
         throttle_cfg->buckets[THROTTLE_BPS_TOTAL].avg =
             qemu_opt_get_number(opts, "throttling.bps-total", 0);
         throttle_cfg->buckets[THROTTLE_BPS_READ].avg  =
@@ -2611,7 +2611,7 @@ void qmp_block_set_io_throttle(const char *device, int64_t bps, int64_t bps_rd,
         goto out;
     }
 
-    memset(&cfg, 0, sizeof(cfg));
+    throttle_config_init(&cfg);
     cfg.buckets[THROTTLE_BPS_TOTAL].avg = bps;
     cfg.buckets[THROTTLE_BPS_READ].avg  = bps_rd;
     cfg.buckets[THROTTLE_BPS_WRITE].avg = bps_wr;

include/qemu/throttle.h

@@ -114,6 +114,8 @@ void throttle_config(ThrottleState *ts,
 
 void throttle_get_config(ThrottleState *ts, ThrottleConfig *cfg);
 
+void throttle_config_init(ThrottleConfig *cfg);
+
 /* usage */
 bool throttle_schedule_timer(ThrottleState *ts,
                              ThrottleTimers *tt,

tests/test-throttle.c

@@ -35,6 +35,9 @@ static bool double_cmp(double x, double y)
 /* tests for single bucket operations */
 static void test_leak_bucket(void)
 {
+    throttle_config_init(&cfg);
+    bkt = cfg.buckets[THROTTLE_BPS_TOTAL];
+
     /* set initial value */
     bkt.avg = 150;
     bkt.max = 15;
@@ -64,6 +67,9 @@ static void test_compute_wait(void)
     int64_t wait;
     int64_t result;
 
+    throttle_config_init(&cfg);
+    bkt = cfg.buckets[THROTTLE_BPS_TOTAL];
+
     /* no operation limit set */
     bkt.avg = 0;
     bkt.max = 15;
@@ -233,17 +239,17 @@ static void test_enabled(void)
 {
     int i;
 
-    memset(&cfg, 0, sizeof(cfg));
+    throttle_config_init(&cfg);
     g_assert(!throttle_enabled(&cfg));
 
     for (i = 0; i < BUCKETS_COUNT; i++) {
-        memset(&cfg, 0, sizeof(cfg));
+        throttle_config_init(&cfg);
         set_cfg_value(false, i, 150);
         g_assert(throttle_enabled(&cfg));
     }
 
     for (i = 0; i < BUCKETS_COUNT; i++) {
-        memset(&cfg, 0, sizeof(cfg));
+        throttle_config_init(&cfg);
         set_cfg_value(false, i, -150);
         g_assert(!throttle_enabled(&cfg));
     }
@@ -256,29 +262,29 @@ static void test_conflicts_for_one_set(bool is_max,
                                        int read,
                                        int write)
 {
-    memset(&cfg, 0, sizeof(cfg));
+    throttle_config_init(&cfg);
     g_assert(throttle_is_valid(&cfg, NULL));
 
     set_cfg_value(is_max, total, 1);
     set_cfg_value(is_max, read,  1);
     g_assert(!throttle_is_valid(&cfg, NULL));
 
-    memset(&cfg, 0, sizeof(cfg));
+    throttle_config_init(&cfg);
     set_cfg_value(is_max, total, 1);
     set_cfg_value(is_max, write, 1);
     g_assert(!throttle_is_valid(&cfg, NULL));
 
-    memset(&cfg, 0, sizeof(cfg));
+    throttle_config_init(&cfg);
     set_cfg_value(is_max, total, 1);
     set_cfg_value(is_max, read,  1);
     set_cfg_value(is_max, write, 1);
     g_assert(!throttle_is_valid(&cfg, NULL));
 
-    memset(&cfg, 0, sizeof(cfg));
+    throttle_config_init(&cfg);
     set_cfg_value(is_max, total, 1);
     g_assert(throttle_is_valid(&cfg, NULL));
 
-    memset(&cfg, 0, sizeof(cfg));
+    throttle_config_init(&cfg);
     set_cfg_value(is_max, read,  1);
     set_cfg_value(is_max, write, 1);
     g_assert(throttle_is_valid(&cfg, NULL));
@@ -315,7 +321,7 @@ static void test_is_valid_for_value(int value, bool should_be_valid)
     int is_max, index;
     for (is_max = 0; is_max < 2; is_max++) {
         for (index = 0; index < BUCKETS_COUNT; index++) {
-            memset(&cfg, 0, sizeof(cfg));
+            throttle_config_init(&cfg);
             set_cfg_value(is_max, index, value);
             g_assert(throttle_is_valid(&cfg, NULL) == should_be_valid);
         }
@@ -337,7 +343,7 @@ static void test_max_is_missing_limit(void)
     int i;
 
     for (i = 0; i < BUCKETS_COUNT; i++) {
-        memset(&cfg, 0, sizeof(cfg));
+        throttle_config_init(&cfg);
         cfg.buckets[i].max = 100;
         cfg.buckets[i].avg = 0;
         g_assert(!throttle_is_valid(&cfg, NULL));
@@ -552,7 +558,7 @@ static void test_groups(void)
     g_assert(bdrv1->throttle_state == bdrv3->throttle_state);
 
     /* Setting the config of a group member affects the whole group */
-    memset(&cfg1, 0, sizeof(cfg1));
+    throttle_config_init(&cfg1);
     cfg1.buckets[THROTTLE_BPS_READ].avg  = 500000;
     cfg1.buckets[THROTTLE_BPS_WRITE].avg = 285000;
     cfg1.buckets[THROTTLE_OPS_READ].avg  = 20000;

util/throttle.c

@@ -171,10 +171,20 @@ void throttle_timers_attach_aio_context(ThrottleTimers *tt,
                                   tt->write_timer_cb, tt->timer_opaque);
 }
 
+/*
+ * Initialize the ThrottleConfig structure to a valid state
+ * @cfg: the config to initialize
+ */
+void throttle_config_init(ThrottleConfig *cfg)
+{
+    memset(cfg, 0, sizeof(*cfg));
+}
+
 /* To be called first on the ThrottleState */
 void throttle_init(ThrottleState *ts)
 {
     memset(ts, 0, sizeof(ThrottleState));
+    throttle_config_init(&ts->cfg);
 }
 
 /* To be called first on the ThrottleTimers */