Commit 58f72b96 authored Jul 04, 2018 by Vladimir Sementsov-Ogievskiy Committed by John Snow Jul 04, 2018

dirty-bitmap: fix double lock on bitmap enabling



Bitmap lock/unlock were added to bdrv_enable_dirty_bitmap in
8b1402ce, but some places were not updated correspondingly, which
leads to trying to take this lock twice, which is dead-lock. Fix this.

Actually, iotest 199 (about dirty bitmap postcopy migration) is broken
now, and this fixes it.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20180625165745.25259-3-vsementsov@virtuozzo.com
Signed-off-by: John Snow <jsnow@redhat.com>

parent 92bcea40

block/dirty-bitmap.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -250,8 +250,9 @@ void bdrv_enable_dirty_bitmap_locked(BdrvDirtyBitmap *bitmap)
		/* Called with BQL taken. */
		void bdrv_dirty_bitmap_enable_successor(BdrvDirtyBitmap *bitmap)
		{
		assert(bitmap->mutex == bitmap->successor->mutex);
		qemu_mutex_lock(bitmap->mutex);
		bdrv_enable_dirty_bitmap(bitmap->successor);
		bdrv_enable_dirty_bitmap_locked(bitmap->successor);
		qemu_mutex_unlock(bitmap->mutex);
		}

migration/block-dirty-bitmap.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -511,7 +511,7 @@ void dirty_bitmap_mig_before_vm_start(void)
		DirtyBitmapLoadBitmapState *b = item->data;

		if (b->migrated) {
		bdrv_enable_dirty_bitmap(b->bitmap);
		bdrv_enable_dirty_bitmap_locked(b->bitmap);
		} else {
		bdrv_dirty_bitmap_enable_successor(b->bitmap);
		}
		@@ -547,7 +547,7 @@ static void dirty_bitmap_load_complete(QEMUFile f, DirtyBitmapLoadState s)
		if (enabled_bitmaps == NULL) {
		/* in postcopy */
		bdrv_reclaim_dirty_bitmap_locked(s->bs, s->bitmap, &error_abort);
		bdrv_enable_dirty_bitmap(s->bitmap);
		bdrv_enable_dirty_bitmap_locked(s->bitmap);
		} else {
		/* target not started, successor must be empty */
		int64_t count = bdrv_get_dirty_count(s->bitmap);