> -----Original Message-----
> From: Max Reitz [mailto:[email protected]]
> Sent: Tuesday, October 13, 2020 10:47 PM
> To: Chenqun (kuhn) <[email protected]>; [email protected];
> [email protected]
> Cc: [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]; Zhanghailiang <[email protected]>;
> ganqixin <[email protected]>; [email protected]; Euler Robot
> <[email protected]>; Laurent Vivier <[email protected]>; Li Qiang
> <[email protected]>
> Subject: Re: [PATCH v2] migration/block-dirty-bitmap: fix uninitialized
> variable
> warning
>
> On 13.10.20 14:33, Chen Qun wrote:
> > A default value is provided for the variable 'bitmap_name' to avoid compiler
> warning.
> >
> > The compiler show warning:
> > migration/block-dirty-bitmap.c:1090:13: warning: ‘bitmap_name’
> > may be used uninitialized in this function [-Wmaybe-uninitialized]
> > g_strlcpy(s->bitmap_name, bitmap_name,
> sizeof(s->bitmap_name));
> >
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> > Reported-by: Euler Robot <[email protected]>
> > Signed-off-by: Chen Qun <[email protected]>
> > ---
> > Cc: Vladimir Sementsov-Ogievskiy <[email protected]>
> > Cc: Laurent Vivier <[email protected]>
> > Cc: Li Qiang <[email protected]>
> > ---
> > migration/block-dirty-bitmap.c | 9 ++-------
> > 1 file changed, 2 insertions(+), 7 deletions(-)
>
> No objections, semantically, but...
>
> > diff --git a/migration/block-dirty-bitmap.c
> > b/migration/block-dirty-bitmap.c index 5bef793ac0..bcb79c04ce 100644
> > --- a/migration/block-dirty-bitmap.c
> > +++ b/migration/block-dirty-bitmap.c
> > @@ -1064,15 +1064,13 @@ static int dirty_bitmap_load_header(QEMUFile
> *f, DBMLoadState *s,
> > assert(nothing || s->cancelled || !!alias_map ==
> > !!bitmap_alias_map);
> >
> > if (s->flags & DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME) {
> > - const char *bitmap_name;
> > -
> > if (!qemu_get_counted_string(f, s->bitmap_alias)) {
> > error_report("Unable to read bitmap alias string");
> > return -EINVAL;
> > }
> >
> > - if (!s->cancelled) {
> > - if (bitmap_alias_map) {
> > + const char *bitmap_name = s->bitmap_alias;
>
> qemu’s coding style mandates declarations to be placed at the beginning of
> their block, so the declaration has to stay where it is. (Putting the
> assignment
> here looks reasonable.)
>
Hi Max,
Declaration variables here to ensure that the above exceptions(Unable to read
bitmap alias string) are avoided.
If the declaration has to stay where it is, is there a possibility that the
assignment fails?
> > + if (!s->cancelled && bitmap_alias_map) {
> > bitmap_name =
> g_hash_table_lookup(bitmap_alias_map,
> >
> s->bitmap_alias);
>
> This block of course needs to be re-indented.
>
I forgot this. I will update it later.
Thanks,
ChenQun
>
> > if (!bitmap_name) {
> > @@ -1081,9 +1079,6 @@ static int dirty_bitmap_load_header(QEMUFile *f,
> DBMLoadState *s,
> > s->bs->node_name,
> s->node_alias);
> > cancel_incoming_locked(s);
> > }
> > - } else {
> > - bitmap_name = s->bitmap_alias;
> > - }
> > }
> >
> > if (!s->cancelled) {
> >
>
