From: Paolo Bonzini <pbonzini@redhat.com>
Date: Mon, 14 Jun 2021 08:11:26 +0000 (+0200)
Subject: ratelimit: treat zero speed as unlimited
X-Git-Tag: v6.1.0-rc0~53^2~9
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=720507ed95023e45620f305767d12cd716e8b8ca;p=thirdparty%2Fqemu.git

ratelimit: treat zero speed as unlimited

Both users of RateLimit, block-copy.c and blockjob.c, treat
a speed of zero as unlimited, while RateLimit treats it as
"as slow as possible".  The latter is nicer from the code
point of view but pretty useless, so disable rate limiting
if a speed of zero is provided.

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20210614081130.22134-2-eesposit@redhat.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---

diff --git a/include/qemu/ratelimit.h b/include/qemu/ratelimit.h
index 003ea6d5a36..48bf59e8572 100644
--- a/include/qemu/ratelimit.h
+++ b/include/qemu/ratelimit.h
@@ -43,7 +43,11 @@ static inline int64_t ratelimit_calculate_delay(RateLimit *limit, uint64_t n)
     double delay_slices;
 
     QEMU_LOCK_GUARD(&limit->lock);
-    assert(limit->slice_quota && limit->slice_ns);
+    if (!limit->slice_quota) {
+        /* Throttling disabled.  */
+        return 0;
+    }
+    assert(limit->slice_ns);
 
     if (limit->slice_end_time < now) {
         /* Previous, possibly extended, time slice finished; reset the
@@ -83,7 +87,11 @@ static inline void ratelimit_set_speed(RateLimit *limit, uint64_t speed,
 {
     QEMU_LOCK_GUARD(&limit->lock);
     limit->slice_ns = slice_ns;
-    limit->slice_quota = MAX(((double)speed * slice_ns) / 1000000000ULL, 1);
+    if (speed == 0) {
+        limit->slice_quota = 0;
+    } else {
+        limit->slice_quota = MAX(((double)speed * slice_ns) / 1000000000ULL, 1);
+    }
 }
 
 #endif