[Qemu-devel] [PATCH] sheepdog: Fix error message if failed to load vmstate

[Qemu-devel] [PATCH] sheepdog: Fix error message if failed to load vmstate

[Fam Zheng]

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/sheepdog.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/block/sheepdog.c b/block/sheepdog.c
index bd7cbed..a22f838 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -2556,7 +2556,11 @@ static int do_load_save_vmstate(BDRVSheepdogState *s, uint8_t *data,
         }
 
         if (ret < 0) {
-            error_report("failed to save vmstate %s", strerror(errno));
+            if (load) {
+                error_report("failed to load vmstate %s", strerror(errno));
+            } else {
+                error_report("failed to save vmstate %s", strerror(errno));
+            }
             goto cleanup;
         }
 
-- 
2.4.2

Re: [Qemu-devel] [PATCH] sheepdog: Fix error message if failed to load vmstate

[Kevin Wolf]

[ CC to Sheepdog maintainers ]

Am 02.06.2015 um 11:32 hat Fam Zheng geschrieben:
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  block/sheepdog.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/block/sheepdog.c b/block/sheepdog.c
> index bd7cbed..a22f838 100644
> --- a/block/sheepdog.c
> +++ b/block/sheepdog.c
> @@ -2556,7 +2556,11 @@ static int do_load_save_vmstate(BDRVSheepdogState *s, uint8_t *data,
>          }
>  
>          if (ret < 0) {
> -            error_report("failed to save vmstate %s", strerror(errno));
> +            if (load) {
> +                error_report("failed to load vmstate %s", strerror(errno));
> +            } else {
> +                error_report("failed to save vmstate %s", strerror(errno));
> +            }
>              goto cleanup;
>          }

Why do we even print this message? We usually don't do this for a failed
request, and much less so if we don't actually add any information that
isn't covered by the return code. qemu_savevm_state() will already set
an error that is even visible in QMP.

In fact, errno doesn't even contain anything relevant here, or in most
(all?) other places that it's used in the sheepdog block driver.

I think we might be better off just removing the message.

Kevin

Re: [Qemu-devel] [PATCH] sheepdog: Fix error message if failed to load vmstate

[Fam Zheng]

On Tue, 06/02 11:45, Kevin Wolf wrote:
> [ CC to Sheepdog maintainers ]
> 
> Am 02.06.2015 um 11:32 hat Fam Zheng geschrieben:
> > Signed-off-by: Fam Zheng <famz@redhat.com>
> > ---
> >  block/sheepdog.c | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > diff --git a/block/sheepdog.c b/block/sheepdog.c
> > index bd7cbed..a22f838 100644
> > --- a/block/sheepdog.c
> > +++ b/block/sheepdog.c
> > @@ -2556,7 +2556,11 @@ static int do_load_save_vmstate(BDRVSheepdogState *s, uint8_t *data,
> >          }
> >  
> >          if (ret < 0) {
> > -            error_report("failed to save vmstate %s", strerror(errno));
> > +            if (load) {
> > +                error_report("failed to load vmstate %s", strerror(errno));
> > +            } else {
> > +                error_report("failed to save vmstate %s", strerror(errno));
> > +            }
> >              goto cleanup;
> >          }
> 
> Why do we even print this message? We usually don't do this for a failed
> request, and much less so if we don't actually add any information that
> isn't covered by the return code. qemu_savevm_state() will already set
> an error that is even visible in QMP.
> 
> In fact, errno doesn't even contain anything relevant here, or in most
> (all?) other places that it's used in the sheepdog block driver.

Now I followed the called function and agree that reporting errno is not
helpful.  Maybe it's better to do a clean up on error reportings in this
driver, later.

Fam

Re: [Qemu-devel] [PATCH] sheepdog: Fix error message if failed to load vmstate

[Michael Tokarev]

02.06.2015 12:32, Fam Zheng wrote:
>          if (ret < 0) {
> -            error_report("failed to save vmstate %s", strerror(errno));
> +            if (load) {
> +                error_report("failed to load vmstate %s", strerror(errno));
> +            } else {
> +                error_report("failed to save vmstate %s", strerror(errno));
> +            }

 +            error_report("failed to %s vmstate: %s", load ? "load" : "save", strerror(errno));

(note also the addition of ":")
(besides what Kevin said).

Thanks,

/mjt

Re: [Qemu-devel] [PATCH] sheepdog: Fix error message if failed to load vmstate

[Fam Zheng]

On Tue, 06/02 13:16, Michael Tokarev wrote:
> 02.06.2015 12:32, Fam Zheng wrote:
> >          if (ret < 0) {
> > -            error_report("failed to save vmstate %s", strerror(errno));
> > +            if (load) {
> > +                error_report("failed to load vmstate %s", strerror(errno));
> > +            } else {
> > +                error_report("failed to save vmstate %s", strerror(errno));
> > +            }
> 
>  +            error_report("failed to %s vmstate: %s", load ? "load" : "save", strerror(errno));

The reason I didn't use a one-liner was, "git grep 'failed to load vmstate'"
in the code base would just work, besides my eyes also like the readability.

> 
> (note also the addition of ":")

Yes that applies to all error_report() in this file.

> (besides what Kevin said).
> 
> Thanks,

Thanks,

Fam

Re: [Qemu-devel] [Qemu-block] [PATCH] sheepdog: Fix error message if failed to load vmstate

[John Snow]

On 06/02/2015 06:26 AM, Fam Zheng wrote:
> On Tue, 06/02 13:16, Michael Tokarev wrote:
>> 02.06.2015 12:32, Fam Zheng wrote:
>>>          if (ret < 0) {
>>> -            error_report("failed to save vmstate %s", strerror(errno));
>>> +            if (load) {
>>> +                error_report("failed to load vmstate %s", strerror(errno));
>>> +            } else {
>>> +                error_report("failed to save vmstate %s", strerror(errno));
>>> +            }
>>
>>  +            error_report("failed to %s vmstate: %s", load ? "load" : "save", strerror(errno));
> 
> The reason I didn't use a one-liner was, "git grep 'failed to load vmstate'"
> in the code base would just work, besides my eyes also like the readability.
> 

+1, Error messages should be kept on one line and intact where possible
and convenient. Greppable code is happy code.

>>
>> (note also the addition of ":")
> 
> Yes that applies to all error_report() in this file.
> 
>> (besides what Kevin said).
>>
>> Thanks,
> 
> Thanks,
> 
> Fam
>