[Qemu-devel] [PATCH] Avoid divide by zero when there is no block device to migrate

[Pierre Riteau <Pierre.Riteau@irisa.fr>]

When block migration is requested and no read-write block device is
present, a divide by zero exception is triggered because
total_sector_sum equals zero.

Signed-off-by: Pierre Riteau <Pierre.Riteau@irisa.fr>
---
 block-migration.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/block-migration.c b/block-migration.c
index 1475325..d62d63e 100644
--- a/block-migration.c
+++ b/block-migration.c
@@ -350,7 +350,11 @@ static int blk_mig_save_bulked_block(Monitor *mon, QEMUFile *f)
         }
     }
 
-    progress = completed_sector_sum * 100 / block_mig_state.total_sector_sum;
+    if (block_mig_state.total_sector_sum != 0) {
+        progress = completed_sector_sum * 100 / block_mig_state.total_sector_sum;
+    } else {
+        progress = 100;
+    }
     if (progress != block_mig_state.prev_progress) {
         block_mig_state.prev_progress = progress;
         qemu_put_be64(f, (progress << BDRV_SECTOR_BITS)
-- 
1.7.3.4