* [PATCH] migration/block-dirty-bitmap: fix uninitialized variable warning
@ 2020-10-10 11:07 Chen Qun
2020-10-11 1:55 ` Li Qiang
2020-10-12 15:31 ` Laurent Vivier
0 siblings, 2 replies; 9+ messages in thread
From: Chen Qun @ 2020-10-10 11:07 UTC (permalink / raw)
To: qemu-devel, qemu-trivial
Cc: fam, ganqixin, vsementsov, zhang.zhanghailiang, qemu-block,
quintela, dgilbert, mreitz, stefanha, Euler Robot, Chen Qun,
jsnow
This if statement judgment is redundant and it will cause a 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 <euler.robot@huawei.com>
Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
---
migration/block-dirty-bitmap.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index 5bef793ac0..e09ea4f22b 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -1084,9 +1084,7 @@ static int dirty_bitmap_load_header(QEMUFile *f, DBMLoadState *s,
} else {
bitmap_name = s->bitmap_alias;
}
- }
- if (!s->cancelled) {
g_strlcpy(s->bitmap_name, bitmap_name, sizeof(s->bitmap_name));
s->bitmap = bdrv_find_dirty_bitmap(s->bs, s->bitmap_name);
--
2.23.0
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH] migration/block-dirty-bitmap: fix uninitialized variable warning
2020-10-10 11:07 [PATCH] migration/block-dirty-bitmap: fix uninitialized variable warning Chen Qun
@ 2020-10-11 1:55 ` Li Qiang
2020-10-12 15:31 ` Laurent Vivier
1 sibling, 0 replies; 9+ messages in thread
From: Li Qiang @ 2020-10-11 1:55 UTC (permalink / raw)
To: Chen Qun
Cc: Fam Zheng, vsementsov, zhanghailiang, qemu-block, Juan Quintela,
qemu-trivial, Stefan Hajnoczi, Qemu Developers,
Dr. David Alan Gilbert, ganqixin, Euler Robot, Max Reitz,
John Snow
Chen Qun <kuhn.chenqun@huawei.com> 于2020年10月10日周六 下午7:08写道：
>
> This if statement judgment is redundant and it will cause a 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 <euler.robot@huawei.com>
> Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
> ---
> migration/block-dirty-bitmap.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
> index 5bef793ac0..e09ea4f22b 100644
> --- a/migration/block-dirty-bitmap.c
> +++ b/migration/block-dirty-bitmap.c
> @@ -1084,9 +1084,7 @@ static int dirty_bitmap_load_header(QEMUFile *f, DBMLoadState *s,
> } else {
> bitmap_name = s->bitmap_alias;
> }
> - }
>
> - if (!s->cancelled) {
> g_strlcpy(s->bitmap_name, bitmap_name, sizeof(s->bitmap_name));
> s->bitmap = bdrv_find_dirty_bitmap(s->bs, s->bitmap_name);
>
> --
> 2.23.0
>
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] migration/block-dirty-bitmap: fix uninitialized variable warning
2020-10-10 11:07 [PATCH] migration/block-dirty-bitmap: fix uninitialized variable warning Chen Qun
2020-10-11 1:55 ` Li Qiang
@ 2020-10-12 15:31 ` Laurent Vivier
2020-10-13 1:34 ` Li Qiang
1 sibling, 1 reply; 9+ messages in thread
From: Laurent Vivier @ 2020-10-12 15:31 UTC (permalink / raw)
To: Chen Qun, qemu-devel, qemu-trivial
Cc: fam, vsementsov, zhang.zhanghailiang, qemu-block, quintela, jsnow,
stefanha, dgilbert, mreitz, ganqixin, Euler Robot
Le 10/10/2020 à 13:07, Chen Qun a écrit :
> This if statement judgment is redundant and it will cause a 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 <euler.robot@huawei.com>
> Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
> ---
> migration/block-dirty-bitmap.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
> index 5bef793ac0..e09ea4f22b 100644
> --- a/migration/block-dirty-bitmap.c
> +++ b/migration/block-dirty-bitmap.c
> @@ -1084,9 +1084,7 @@ static int dirty_bitmap_load_header(QEMUFile *f, DBMLoadState *s,
> } else {
> bitmap_name = s->bitmap_alias;
> }
> - }
>
> - if (!s->cancelled) {
> g_strlcpy(s->bitmap_name, bitmap_name, sizeof(s->bitmap_name));
> s->bitmap = bdrv_find_dirty_bitmap(s->bs, s->bitmap_name);
>
>
I don't think it's correct as "cancel_incoming_locked(s)" can change the
value of "s->cancelled".
Thanks,
Laurent
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] migration/block-dirty-bitmap: fix uninitialized variable warning
2020-10-12 15:31 ` Laurent Vivier
@ 2020-10-13 1:34 ` Li Qiang
2020-10-13 7:11 ` Laurent Vivier
2020-10-13 7:27 ` Chenqun (kuhn)
0 siblings, 2 replies; 9+ messages in thread
From: Li Qiang @ 2020-10-13 1:34 UTC (permalink / raw)
To: Laurent Vivier
Cc: Fam Zheng, ganqixin, vsementsov, zhanghailiang, qemu-block,
Juan Quintela, qemu-trivial, Qemu Developers,
Dr. David Alan Gilbert, Stefan Hajnoczi, Euler Robot, Chen Qun,
Max Reitz, John Snow
Laurent Vivier <laurent@vivier.eu> 于2020年10月12日周一 下午11:33写道：
>
> Le 10/10/2020 à 13:07, Chen Qun a écrit :
> > This if statement judgment is redundant and it will cause a 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 <euler.robot@huawei.com>
> > Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
> > ---
> > migration/block-dirty-bitmap.c | 2 --
> > 1 file changed, 2 deletions(-)
> >
> > diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
> > index 5bef793ac0..e09ea4f22b 100644
> > --- a/migration/block-dirty-bitmap.c
> > +++ b/migration/block-dirty-bitmap.c
> > @@ -1084,9 +1084,7 @@ static int dirty_bitmap_load_header(QEMUFile *f, DBMLoadState *s,
> > } else {
> > bitmap_name = s->bitmap_alias;
> > }
> > - }
> >
> > - if (!s->cancelled) {
> > g_strlcpy(s->bitmap_name, bitmap_name, sizeof(s->bitmap_name));
> > s->bitmap = bdrv_find_dirty_bitmap(s->bs, s->bitmap_name);
> >
> >
>
> I don't think it's correct as "cancel_incoming_locked(s)" can change the
> value of "s->cancelled".
>
Hi Laurent,
You're right. So I think this can simply assign 'bitmap_name' to NULL
to make compiler happy.
Thanks,
Li Qiang
> Thanks,
> Laurent
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] migration/block-dirty-bitmap: fix uninitialized variable warning
2020-10-13 1:34 ` Li Qiang
@ 2020-10-13 7:11 ` Laurent Vivier
2020-10-13 7:49 ` Chenqun (kuhn)
2020-10-13 7:27 ` Chenqun (kuhn)
1 sibling, 1 reply; 9+ messages in thread
From: Laurent Vivier @ 2020-10-13 7:11 UTC (permalink / raw)
To: Li Qiang
Cc: Fam Zheng, vsementsov, zhanghailiang, qemu-block, Juan Quintela,
qemu-trivial, Stefan Hajnoczi, Qemu Developers,
Dr. David Alan Gilbert, ganqixin, Euler Robot, Chen Qun,
Max Reitz, John Snow
Le 13/10/2020 à 03:34, Li Qiang a écrit :
> Laurent Vivier <laurent@vivier.eu> 于2020年10月12日周一 下午11:33写道：
>>
>> Le 10/10/2020 à 13:07, Chen Qun a écrit :
>>> This if statement judgment is redundant and it will cause a 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 <euler.robot@huawei.com>
>>> Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
>>> ---
>>> migration/block-dirty-bitmap.c | 2 --
>>> 1 file changed, 2 deletions(-)
>>>
>>> diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
>>> index 5bef793ac0..e09ea4f22b 100644
>>> --- a/migration/block-dirty-bitmap.c
>>> +++ b/migration/block-dirty-bitmap.c
>>> @@ -1084,9 +1084,7 @@ static int dirty_bitmap_load_header(QEMUFile *f, DBMLoadState *s,
>>> } else {
>>> bitmap_name = s->bitmap_alias;
>>> }
>>> - }
>>>
>>> - if (!s->cancelled) {
>>> g_strlcpy(s->bitmap_name, bitmap_name, sizeof(s->bitmap_name));
>>> s->bitmap = bdrv_find_dirty_bitmap(s->bs, s->bitmap_name);
>>>
>>>
>>
>> I don't think it's correct as "cancel_incoming_locked(s)" can change the
>> value of "s->cancelled".
>>
>
> Hi Laurent,
>
> You're right. So I think this can simply assign 'bitmap_name' to NULL
> to make compiler happy.
Yes, and adding a comment before the second "if (!s->cancelled) {" to
explain the value can be changed by "cancel_incoming_locked(s)" would
avoid to have this kind of patch posted regularly to the ML.
Thanks,
Laurent
^ permalink raw reply [flat|nested] 9+ messages in thread
* RE: [PATCH] migration/block-dirty-bitmap: fix uninitialized variable warning
2020-10-13 1:34 ` Li Qiang
2020-10-13 7:11 ` Laurent Vivier
@ 2020-10-13 7:27 ` Chenqun (kuhn)
1 sibling, 0 replies; 9+ messages in thread
From: Chenqun (kuhn) @ 2020-10-13 7:27 UTC (permalink / raw)
To: Li Qiang, Laurent Vivier
Cc: Fam Zheng, ganqixin, vsementsov@virtuozzo.com, Zhanghailiang,
qemu-block@nongnu.org, Juan Quintela, qemu-trivial@nongnu.org,
Qemu Developers, Dr. David Alan Gilbert, Stefan Hajnoczi,
Euler Robot, Max Reitz, John Snow
migration/block-dirty-bitmap.c
> > > b/migration/block-dirty-bitmap.c index 5bef793ac0..e09ea4f22b 100644
> > > --- a/migration/block-dirty-bitmap.c
> > > +++ b/migration/block-dirty-bitmap.c
> > > @@ -1084,9 +1084,7 @@ static int dirty_bitmap_load_header(QEMUFile
> *f, DBMLoadState *s,
> > > } else {
> > > bitmap_name = s->bitmap_alias;
> > > }
> > > - }
> > >
> > > - if (!s->cancelled) {
> > > g_strlcpy(s->bitmap_name, bitmap_name,
> sizeof(s->bitmap_name));
> > > s->bitmap = bdrv_find_dirty_bitmap(s->bs,
> > > s->bitmap_name);
> > >
> > >
> >
> > I don't think it's correct as "cancel_incoming_locked(s)" can change
> > the value of "s->cancelled".
> >
Hi Laurent,
Yes, you're right. It will be modified value when cancel_incoming_locked is executed.
Thanks.
> So I think this can simply assign 'bitmap_name' to NULL to make
> compiler happy.
>
Hi Qiang,
I think your suggestion is feasible.
But can we just give it a default value when defining variables?
I think the default value could be "bitmap_name = s->bitmap_alias",
and then we can delete the else statement above.
Thanks,
Chen Qun
^ permalink raw reply [flat|nested] 9+ messages in thread
* RE: [PATCH] migration/block-dirty-bitmap: fix uninitialized variable warning
2020-10-13 7:11 ` Laurent Vivier
@ 2020-10-13 7:49 ` Chenqun (kuhn)
2020-10-13 11:32 ` Vladimir Sementsov-Ogievskiy
0 siblings, 1 reply; 9+ messages in thread
From: Chenqun (kuhn) @ 2020-10-13 7:49 UTC (permalink / raw)
To: Laurent Vivier, Li Qiang
Cc: Fam Zheng, vsementsov@virtuozzo.com, Zhanghailiang,
qemu-block@nongnu.org, Juan Quintela, qemu-trivial@nongnu.org,
Stefan Hajnoczi, Qemu Developers, Dr. David Alan Gilbert,
ganqixin, Euler Robot, Max Reitz, John Snow
> -----Original Message-----
> From: Laurent Vivier [mailto:laurent@vivier.eu]
> Sent: Tuesday, October 13, 2020 3:11 PM
> To: Li Qiang <liq3ea@gmail.com>
> Cc: Fam Zheng <fam@euphon.net>; ganqixin <ganqixin@huawei.com>;
> vsementsov@virtuozzo.com; Zhanghailiang
> <zhang.zhanghailiang@huawei.com>; qemu-block@nongnu.org; Juan Quintela
> <quintela@redhat.com>; qemu-trivial@nongnu.org; Qemu Developers
> <qemu-devel@nongnu.org>; Dr. David Alan Gilbert <dgilbert@redhat.com>;
> Stefan Hajnoczi <stefanha@redhat.com>; Euler Robot
> <euler.robot@huawei.com>; Chenqun (kuhn) <kuhn.chenqun@huawei.com>;
> Max Reitz <mreitz@redhat.com>; John Snow <jsnow@redhat.com>
> Subject: Re: [PATCH] migration/block-dirty-bitmap: fix uninitialized variable
> warning
>
> Le 13/10/2020 à 03:34, Li Qiang a écrit :
> > Laurent Vivier <laurent@vivier.eu> 于2020年10月12日周一 下午11:33
> 写道：
> >>
> >> Le 10/10/2020 à 13:07, Chen Qun a écrit :
> >>> This if statement judgment is redundant and it will cause a 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 <euler.robot@huawei.com>
> >>> Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
> >>> ---
> >>> migration/block-dirty-bitmap.c | 2 --
> >>> 1 file changed, 2 deletions(-)
> >>>
> >>> diff --git a/migration/block-dirty-bitmap.c
> >>> b/migration/block-dirty-bitmap.c index 5bef793ac0..e09ea4f22b 100644
> >>> --- a/migration/block-dirty-bitmap.c
> >>> +++ b/migration/block-dirty-bitmap.c
> >>> @@ -1084,9 +1084,7 @@ static int dirty_bitmap_load_header(QEMUFile
> *f, DBMLoadState *s,
> >>> } else {
> >>> bitmap_name = s->bitmap_alias;
> >>> }
> >>> - }
> >>>
> >>> - if (!s->cancelled) {
> >>> g_strlcpy(s->bitmap_name, bitmap_name,
> sizeof(s->bitmap_name));
> >>> s->bitmap = bdrv_find_dirty_bitmap(s->bs,
> >>> s->bitmap_name);
> >>>
> >>>
> >>
> >> I don't think it's correct as "cancel_incoming_locked(s)" can change
> >> the value of "s->cancelled".
> >>
> >
> > Hi Laurent,
> >
> > You're right. So I think this can simply assign 'bitmap_name' to NULL
> > to make compiler happy.
>
> Yes, and adding a comment before the second "if (!s->cancelled) {" to explain
> the value can be changed by "cancel_incoming_locked(s)" would avoid to have
> this kind of patch posted regularly to the ML.
>
Hi Laurent,
We give the bitmap_name a default value (s->bitmap_alias) so that we can remove the assignment of the else branch statement.
And then we merge the two if statements("if (!s->cancelled)", "if (bitmap_alias_map)") , avoids confusion the two "if (!s->cancelled)".
Thanks,
Chen Qun
The code show as that:
@@ -1064,15 +1064,14 @@ 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;
+ const char *bitmap_name = s->bitmap_alias;
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) {
+ if (!s->cancelled && bitmap_alias_map) {
bitmap_name = g_hash_table_lookup(bitmap_alias_map,
s->bitmap_alias);
if (!bitmap_name) {
@@ -1081,9 +1080,6 @@ 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) {
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] migration/block-dirty-bitmap: fix uninitialized variable warning
2020-10-13 7:49 ` Chenqun (kuhn)
@ 2020-10-13 11:32 ` Vladimir Sementsov-Ogievskiy
2020-10-13 11:49 ` Chenqun (kuhn)
0 siblings, 1 reply; 9+ messages in thread
From: Vladimir Sementsov-Ogievskiy @ 2020-10-13 11:32 UTC (permalink / raw)
To: Chenqun (kuhn), Laurent Vivier, Li Qiang
Cc: Fam Zheng, ganqixin, Zhanghailiang, qemu-block@nongnu.org,
Juan Quintela, qemu-trivial@nongnu.org, Qemu Developers,
Dr. David Alan Gilbert, Stefan Hajnoczi, Euler Robot, Max Reitz,
John Snow
13.10.2020 10:49, Chenqun (kuhn) wrote:
>> -----Original Message-----
>> From: Laurent Vivier [mailto:laurent@vivier.eu]
>> Sent: Tuesday, October 13, 2020 3:11 PM
>> To: Li Qiang <liq3ea@gmail.com>
>> Cc: Fam Zheng <fam@euphon.net>; ganqixin <ganqixin@huawei.com>;
>> vsementsov@virtuozzo.com; Zhanghailiang
>> <zhang.zhanghailiang@huawei.com>; qemu-block@nongnu.org; Juan Quintela
>> <quintela@redhat.com>; qemu-trivial@nongnu.org; Qemu Developers
>> <qemu-devel@nongnu.org>; Dr. David Alan Gilbert <dgilbert@redhat.com>;
>> Stefan Hajnoczi <stefanha@redhat.com>; Euler Robot
>> <euler.robot@huawei.com>; Chenqun (kuhn) <kuhn.chenqun@huawei.com>;
>> Max Reitz <mreitz@redhat.com>; John Snow <jsnow@redhat.com>
>> Subject: Re: [PATCH] migration/block-dirty-bitmap: fix uninitialized variable
>> warning
>>
>> Le 13/10/2020 à 03:34, Li Qiang a écrit :
>>> Laurent Vivier <laurent@vivier.eu> 于2020年10月12日周一 下午11:33
>> 写道：
>>>>
>>>> Le 10/10/2020 à 13:07, Chen Qun a écrit :
>>>>> This if statement judgment is redundant and it will cause a 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 <euler.robot@huawei.com>
>>>>> Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
>>>>> ---
>>>>> migration/block-dirty-bitmap.c | 2 --
>>>>> 1 file changed, 2 deletions(-)
>>>>>
>>>>> diff --git a/migration/block-dirty-bitmap.c
>>>>> b/migration/block-dirty-bitmap.c index 5bef793ac0..e09ea4f22b 100644
>>>>> --- a/migration/block-dirty-bitmap.c
>>>>> +++ b/migration/block-dirty-bitmap.c
>>>>> @@ -1084,9 +1084,7 @@ static int dirty_bitmap_load_header(QEMUFile
>> *f, DBMLoadState *s,
>>>>> } else {
>>>>> bitmap_name = s->bitmap_alias;
>>>>> }
>>>>> - }
>>>>>
>>>>> - if (!s->cancelled) {
>>>>> g_strlcpy(s->bitmap_name, bitmap_name,
>> sizeof(s->bitmap_name));
>>>>> s->bitmap = bdrv_find_dirty_bitmap(s->bs,
>>>>> s->bitmap_name);
>>>>>
>>>>>
>>>>
>>>> I don't think it's correct as "cancel_incoming_locked(s)" can change
>>>> the value of "s->cancelled".
>>>>
>>>
>>> Hi Laurent,
>>>
>>> You're right. So I think this can simply assign 'bitmap_name' to NULL
>>> to make compiler happy.
>>
>> Yes, and adding a comment before the second "if (!s->cancelled) {" to explain
>> the value can be changed by "cancel_incoming_locked(s)" would avoid to have
>> this kind of patch posted regularly to the ML.
>>
> Hi Laurent,
>
> We give the bitmap_name a default value (s->bitmap_alias) so that we can remove the assignment of the else branch statement.
>
> And then we merge the two if statements("if (!s->cancelled)", "if (bitmap_alias_map)") , avoids confusion the two "if (!s->cancelled)".
>
> Thanks,
> Chen Qun
>
>
> The code show as that:
> @@ -1064,15 +1064,14 @@ 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;
> + const char *bitmap_name = s->bitmap_alias;
>
> 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) {
> + if (!s->cancelled && bitmap_alias_map) {
> bitmap_name = g_hash_table_lookup(bitmap_alias_map,
> s->bitmap_alias);
> if (!bitmap_name) {
> @@ -1081,9 +1080,6 @@ 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) {
>
Sounds good.
--
Best regards,
Vladimir
^ permalink raw reply [flat|nested] 9+ messages in thread
* RE: [PATCH] migration/block-dirty-bitmap: fix uninitialized variable warning
2020-10-13 11:32 ` Vladimir Sementsov-Ogievskiy
@ 2020-10-13 11:49 ` Chenqun (kuhn)
0 siblings, 0 replies; 9+ messages in thread
From: Chenqun (kuhn) @ 2020-10-13 11:49 UTC (permalink / raw)
To: Vladimir Sementsov-Ogievskiy, Laurent Vivier, Li Qiang
Cc: Fam Zheng, Zhanghailiang, qemu-block@nongnu.org, Juan Quintela,
qemu-trivial@nongnu.org, Stefan Hajnoczi, Qemu Developers,
Dr. David Alan Gilbert, ganqixin, Euler Robot, Max Reitz,
John Snow
> >>>> Le 10/10/2020 à 13:07, Chen Qun a écrit :
> >>>>> This if statement judgment is redundant and it will cause a 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 <euler.robot@huawei.com>
> >>>>> Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
> >>>>> ---
> >>>>> migration/block-dirty-bitmap.c | 2 --
> >>>>> 1 file changed, 2 deletions(-)
> >>>>>
> >>>>> diff --git a/migration/block-dirty-bitmap.c
> >>>>> b/migration/block-dirty-bitmap.c index 5bef793ac0..e09ea4f22b
> >>>>> 100644
> >>>>> --- a/migration/block-dirty-bitmap.c
> >>>>> +++ b/migration/block-dirty-bitmap.c
> >>>>> @@ -1084,9 +1084,7 @@ static int
> dirty_bitmap_load_header(QEMUFile
> >> *f, DBMLoadState *s,
> >>>>> } else {
> >>>>> bitmap_name = s->bitmap_alias;
> >>>>> }
> >>>>> - }
> >>>>>
> >>>>> - if (!s->cancelled) {
> >>>>> g_strlcpy(s->bitmap_name, bitmap_name,
> >> sizeof(s->bitmap_name));
> >>>>> s->bitmap = bdrv_find_dirty_bitmap(s->bs,
> >>>>> s->bitmap_name);
> >>>>>
> >>>>>
> >>>>
> >>>> I don't think it's correct as "cancel_incoming_locked(s)" can
> >>>> change the value of "s->cancelled".
> >>>>
> >>>
> >>> Hi Laurent,
> >>>
> >>> You're right. So I think this can simply assign 'bitmap_name' to
> >>> NULL to make compiler happy.
> >>
> >> Yes, and adding a comment before the second "if (!s->cancelled) {" to
> >> explain the value can be changed by "cancel_incoming_locked(s)" would
> >> avoid to have this kind of patch posted regularly to the ML.
> >>
> > Hi Laurent,
> >
> > We give the bitmap_name a default value (s->bitmap_alias) so that we can
> remove the assignment of the else branch statement.
> >
> > And then we merge the two if statements("if (!s->cancelled)", "if
> (bitmap_alias_map)") , avoids confusion the two "if (!s->cancelled)".
> >
> > Thanks,
> > Chen Qun
> >
> >
> > The code show as that:
> > @@ -1064,15 +1064,14 @@ 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;
> > + const char *bitmap_name = s->bitmap_alias;
> >
> > 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) {
> > + if (!s->cancelled && bitmap_alias_map) {
> > bitmap_name =
> g_hash_table_lookup(bitmap_alias_map,
> >
> s->bitmap_alias);
> > if (!bitmap_name) {
> > @@ -1081,9 +1080,6 @@ 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) {
> >
>
> Sounds good.
>
OK, I'll update it later.
Thanks,
Chen Qun
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2020-10-13 11:56 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2020-10-10 11:07 [PATCH] migration/block-dirty-bitmap: fix uninitialized variable warning Chen Qun
2020-10-11 1:55 ` Li Qiang
2020-10-12 15:31 ` Laurent Vivier
2020-10-13 1:34 ` Li Qiang
2020-10-13 7:11 ` Laurent Vivier
2020-10-13 7:49 ` Chenqun (kuhn)
2020-10-13 11:32 ` Vladimir Sementsov-Ogievskiy
2020-10-13 11:49 ` Chenqun (kuhn)
2020-10-13 7:27 ` Chenqun (kuhn)
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