migration/postcopy: break the loop when there is no more page to discard

When one is equal or bigger then end, it means there is no page to
discard. Just break the loop in this case instead of processing it.

No functional change, just refactor it a little.

Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Message-Id: <20190627020822.15485-3-richardw.yang@linux.intel.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

diff --git a/migration/ram.c b/migration/ram.c
index 68bc11c9e7a3f43921baa57ce3ce78dac2e8efda..8a97dadec4973cb6b4b7cf1c0b94a0f0b9e3228d 100644 (file)
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -2864,23 +2864,23 @@ static int postcopy_send_discard_bm_ram(MigrationState *ms,
 
     for (current = 0; current < end; ) {
         unsigned long one = find_next_bit(unsentmap, end, current);
+        unsigned long zero, discard_length;
 
-        if (one < end) {
-            unsigned long zero = find_next_zero_bit(unsentmap, end, one + 1);
-            unsigned long discard_length;
+        if (one >= end) {
+            break;
+        }
 
-            if (zero >= end) {
-                discard_length = end - one;
-            } else {
-                discard_length = zero - one;
-            }
-            if (discard_length) {
-                postcopy_discard_send_range(ms, pds, one, discard_length);
-            }
-            current = one + discard_length;
+        zero = find_next_zero_bit(unsentmap, end, one + 1);
+
+        if (zero >= end) {
+            discard_length = end - one;
         } else {
-            current = one;
+            discard_length = zero - one;
+        }
+        if (discard_length) {
+            postcopy_discard_send_range(ms, pds, one, discard_length);
         }
+        current = one + discard_length;
     }
 
     return 0;