block/accounting: Use lock guard macros

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

Signed-off-by: Gan Qixin <ganqixin@huawei.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20201203075055.127773-2-ganqixin@huawei.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/accounting.c

@@ -199,29 +199,27 @@ static void block_account_one_io(BlockAcctStats *stats, BlockAcctCookie *cookie,
         return;
     }
 
-    qemu_mutex_lock(&stats->lock);
-
-    if (failed) {
-        stats->failed_ops[cookie->type]++;
-    } else {
-        stats->nr_bytes[cookie->type] += cookie->bytes;
-        stats->nr_ops[cookie->type]++;
-    }
+    WITH_QEMU_LOCK_GUARD(&stats->lock) {
+        if (failed) {
+            stats->failed_ops[cookie->type]++;
+        } else {
+            stats->nr_bytes[cookie->type] += cookie->bytes;
+            stats->nr_ops[cookie->type]++;
+        }
 
-    block_latency_histogram_account(&stats->latency_histogram[cookie->type],
-                                    latency_ns);
+        block_latency_histogram_account(&stats->latency_histogram[cookie->type],
+                                        latency_ns);
 
-    if (!failed || stats->account_failed) {
-        stats->total_time_ns[cookie->type] += latency_ns;
-        stats->last_access_time_ns = time_ns;
+        if (!failed || stats->account_failed) {
+            stats->total_time_ns[cookie->type] += latency_ns;
+            stats->last_access_time_ns = time_ns;
 
-        QSLIST_FOREACH(s, &stats->intervals, entries) {
-            timed_average_account(&s->latency[cookie->type], latency_ns);
+            QSLIST_FOREACH(s, &stats->intervals, entries) {
+                timed_average_account(&s->latency[cookie->type], latency_ns);
+            }
         }
     }
 
-    qemu_mutex_unlock(&stats->lock);
-
     cookie->type = BLOCK_ACCT_NONE;
 }