block/throttle-groups: Use lock guard macros

Replace manual lock()/unlock() calls with lock guard macros
(QEMU_LOCK_GUARD/WITH_QEMU_LOCK_GUARD) in block/throttle-groups.

Signed-off-by: Gan Qixin <ganqixin@huawei.com>
Message-Id: <20201203075055.127773-4-ganqixin@huawei.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/throttle-groups.c

@@ -546,7 +546,7 @@ void throttle_group_register_tgm(ThrottleGroupMember *tgm,
     tgm->aio_context = ctx;
     qatomic_set(&tgm->restart_pending, 0);
 
-    qemu_mutex_lock(&tg->lock);
+    QEMU_LOCK_GUARD(&tg->lock);
     /* If the ThrottleGroup is new set this ThrottleGroupMember as the token */
     for (i = 0; i < 2; i++) {
         if (!tg->tokens[i]) {
@@ -565,8 +565,6 @@ void throttle_group_register_tgm(ThrottleGroupMember *tgm,
     qemu_co_mutex_init(&tgm->throttled_reqs_lock);
     qemu_co_queue_init(&tgm->throttled_reqs[0]);
     qemu_co_queue_init(&tgm->throttled_reqs[1]);
-
-    qemu_mutex_unlock(&tg->lock);
 }
 
 /* Unregister a ThrottleGroupMember from its group, removing it from the list,
@@ -594,25 +592,25 @@ void throttle_group_unregister_tgm(ThrottleGroupMember *tgm)
     /* Wait for throttle_group_restart_queue_entry() coroutines to finish */
     AIO_WAIT_WHILE(tgm->aio_context, qatomic_read(&tgm->restart_pending) > 0);
 
-    qemu_mutex_lock(&tg->lock);
-    for (i = 0; i < 2; i++) {
-        assert(tgm->pending_reqs[i] == 0);
-        assert(qemu_co_queue_empty(&tgm->throttled_reqs[i]));
-        assert(!timer_pending(tgm->throttle_timers.timers[i]));
-        if (tg->tokens[i] == tgm) {
-            token = throttle_group_next_tgm(tgm);
-            /* Take care of the case where this is the last tgm in the group */
-            if (token == tgm) {
-                token = NULL;
+    WITH_QEMU_LOCK_GUARD(&tg->lock) {
+        for (i = 0; i < 2; i++) {
+            assert(tgm->pending_reqs[i] == 0);
+            assert(qemu_co_queue_empty(&tgm->throttled_reqs[i]));
+            assert(!timer_pending(tgm->throttle_timers.timers[i]));
+            if (tg->tokens[i] == tgm) {
+                token = throttle_group_next_tgm(tgm);
+                /* Take care of the case where this is the last tgm in the group */
+                if (token == tgm) {
+                    token = NULL;
+                }
+                tg->tokens[i] = token;
             }
-            tg->tokens[i] = token;
         }
-    }
 
-    /* remove the current tgm from the list */
-    QLIST_REMOVE(tgm, round_robin);
-    throttle_timers_destroy(&tgm->throttle_timers);
-    qemu_mutex_unlock(&tg->lock);
+        /* remove the current tgm from the list */
+        QLIST_REMOVE(tgm, round_robin);
+        throttle_timers_destroy(&tgm->throttle_timers);
+    }
 
     throttle_group_unref(&tg->ts);
     tgm->throttle_state = NULL;
@@ -638,14 +636,14 @@ void throttle_group_detach_aio_context(ThrottleGroupMember *tgm)
     assert(qemu_co_queue_empty(&tgm->throttled_reqs[1]));
 
     /* Kick off next ThrottleGroupMember, if necessary */
-    qemu_mutex_lock(&tg->lock);
-    for (i = 0; i < 2; i++) {
-        if (timer_pending(tt->timers[i])) {
-            tg->any_timer_armed[i] = false;
-            schedule_next_request(tgm, i);
+    WITH_QEMU_LOCK_GUARD(&tg->lock) {
+        for (i = 0; i < 2; i++) {
+            if (timer_pending(tt->timers[i])) {
+                tg->any_timer_armed[i] = false;
+                schedule_next_request(tgm, i);
+            }
         }
     }
-    qemu_mutex_unlock(&tg->lock);
 
     throttle_timers_detach_aio_context(tt);
     tgm->aio_context = NULL;