On Fri, May 05, 2017 at 12:47:35PM +0200, Paolo Bonzini wrote: > > > On 05/05/2017 12:36, Stefan Hajnoczi wrote: > > On Thu, Apr 20, 2017 at 02:00:57PM +0200, Paolo Bonzini wrote: > >> @@ -410,6 +442,18 @@ int bdrv_get_dirty(BlockDriverState *bs, > >> BdrvDirtyBitmap *bitmap, > >> } > >> } > >> > >> +int bdrv_get_dirty(BlockDriverState *bs, BdrvDirtyBitmap *bitmap, > >> + int64_t sector) > > > > Is it a good idea to offer an unlocked bdrv_get_dirty() API? It > > encourages non-atomic access to the bitmap, e.g. > > > > if (bdrv_get_dirty()) { > > ...do something outside the lock... > > bdrv_reset_dirty_bitmap(); > > } > > > > The unlocked API should be test-and-set/clear instead so that callers > > automatically avoid race conditions. > > I'm not sure it's possible to implement atomic test and clear for > HBitmap. But I can look into removing unlocked bdrv_get_dirty, the only > user is block migration.
Removing unlocked bdrv_get_dirty() is good. Stefan
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