[Qemu-devel] [PATCH v2] numa: clarify error message when node index is out of range in -numa dist, ...

[Qemu-devel] [PATCH v2] numa: clarify error message when node index is out of range in -numa dist, ...

[Igor Mammedov]

When using following CLI:
  -numa dist,src=128,dst=1,val=20
user gets a rather confusing error message:
   "Invalid node 128, max possible could be 128"

Where 128 is number of nodes that QEMU supports (MAX_NODES),
while src/dst is an index up to that limit, so it should be
MAX_NODES - 1 in error message.
Make error message to explicitly state valid range for node
index to be more clear.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
---
 numa.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/numa.c b/numa.c
index a3637cc..9f0c49f 100644
--- a/numa.c
+++ b/numa.c
@@ -142,8 +142,8 @@ static void parse_numa_distance(NumaDistOptions *dist, Error **errp)
 
     if (src >= MAX_NODES || dst >= MAX_NODES) {
         error_setg(errp,
-                   "Invalid node %d, max possible could be %d",
-                   MAX(src, dst), MAX_NODES);
+                   "Invalid node %d, The valid node range is [0 - %d]",
+                   MAX(src, dst), MAX_NODES - 1);
         return;
     }
 
-- 
2.7.4

Re: [Qemu-devel] [PATCH v2] numa: clarify error message when node index is out of range in -numa dist, ...

[Andrew Jones]

On Tue, May 15, 2018 at 04:48:33PM +0200, Igor Mammedov wrote:
> When using following CLI:
>   -numa dist,src=128,dst=1,val=20
> user gets a rather confusing error message:
>    "Invalid node 128, max possible could be 128"
> 
> Where 128 is number of nodes that QEMU supports (MAX_NODES),
> while src/dst is an index up to that limit, so it should be
> MAX_NODES - 1 in error message.
> Make error message to explicitly state valid range for node
> index to be more clear.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> Reviewed-by: Andrew Jones <drjones@redhat.com>
> ---
>  numa.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/numa.c b/numa.c
> index a3637cc..9f0c49f 100644
> --- a/numa.c
> +++ b/numa.c
> @@ -142,8 +142,8 @@ static void parse_numa_distance(NumaDistOptions *dist, Error **errp)
>  
>      if (src >= MAX_NODES || dst >= MAX_NODES) {
>          error_setg(errp,
> -                   "Invalid node %d, max possible could be %d",
> -                   MAX(src, dst), MAX_NODES);
> +                   "Invalid node %d, The valid node range is [0 - %d]",
                                      ^ should be a '.'

And maybe need a '.' at the end of the second sentence too, as it's not
an error phrase, but a real sentence.

> +                   MAX(src, dst), MAX_NODES - 1);
>          return;
>      }
>  
> -- 
> 2.7.4
> 

[Qemu-devel] [PATCH v3] numa: clarify error message when node index is out of range in -numa dist, ...

[Igor Mammedov]

When using following CLI:
  -numa dist,src=128,dst=1,val=20
user gets a rather confusing error message:
   "Invalid node 128, max possible could be 128"

Where 128 is number of nodes that QEMU supports (MAX_NODES),
while src/dst is an index up to that limit, so it should be
MAX_NODES - 1 in error message.
Make error message to explicitly state valid range for node
index to be more clear.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
---
v3:
 - s/,/./ in error message
 - add '.' at the end of sentence
---
 numa.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/numa.c b/numa.c
index 188bfdf..d98c106 100644
--- a/numa.c
+++ b/numa.c
@@ -142,8 +142,8 @@ static void parse_numa_distance(NumaDistOptions *dist, Error **errp)
 
     if (src >= MAX_NODES || dst >= MAX_NODES) {
         error_setg(errp,
-                   "Invalid node %d, max possible could be %d",
-                   MAX(src, dst), MAX_NODES);
+                   "Invalid node %d. The valid node range is [0 - %d].",
+                   MAX(src, dst), MAX_NODES - 1);
         return;
     }
 
-- 
2.7.4

Re: [Qemu-devel] [PATCH v2] numa: clarify error message when node index is out of range in -numa dist, ...

[Eric Blake]

On 05/15/2018 10:26 AM, Andrew Jones wrote:
> On Tue, May 15, 2018 at 04:48:33PM +0200, Igor Mammedov wrote:
>> When using following CLI:
>>    -numa dist,src=128,dst=1,val=20
>> user gets a rather confusing error message:
>>     "Invalid node 128, max possible could be 128"
>>
>> Where 128 is number of nodes that QEMU supports (MAX_NODES),
>> while src/dst is an index up to that limit, so it should be
>> MAX_NODES - 1 in error message.
>> Make error message to explicitly state valid range for node
>> index to be more clear.
>>
>> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
>> Reviewed-by: Andrew Jones <drjones@redhat.com>
>> ---

>>       if (src >= MAX_NODES || dst >= MAX_NODES) {
>>           error_setg(errp,
>> -                   "Invalid node %d, max possible could be %d",
>> -                   MAX(src, dst), MAX_NODES);
>> +                   "Invalid node %d, The valid node range is [0 - %d]",
>                                        ^ should be a '.'
> 
> And maybe need a '.' at the end of the second sentence too, as it's not
> an error phrase, but a real sentence.

Actually, error_setg() is documented as taking a single phrase (no '.' 
included), and that if you need a second sentence, it's better to use 
error_append_hint().  Maybe Markus has an opinion on the best way to 
word this error message.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

Re: [Qemu-devel] [PATCH v2] numa: clarify error message when node index is out of range in -numa dist, ...

[Markus Armbruster]

Eric Blake <eblake@redhat.com> writes:

> On 05/15/2018 10:26 AM, Andrew Jones wrote:
>> On Tue, May 15, 2018 at 04:48:33PM +0200, Igor Mammedov wrote:
>>> When using following CLI:
>>>    -numa dist,src=128,dst=1,val=20
>>> user gets a rather confusing error message:
>>>     "Invalid node 128, max possible could be 128"
>>>
>>> Where 128 is number of nodes that QEMU supports (MAX_NODES),
>>> while src/dst is an index up to that limit, so it should be
>>> MAX_NODES - 1 in error message.
>>> Make error message to explicitly state valid range for node
>>> index to be more clear.
>>>
>>> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
>>> Reviewed-by: Andrew Jones <drjones@redhat.com>
>>> ---
>
>>>       if (src >= MAX_NODES || dst >= MAX_NODES) {
>>>           error_setg(errp,
>>> -                   "Invalid node %d, max possible could be %d",
>>> -                   MAX(src, dst), MAX_NODES);
>>> +                   "Invalid node %d, The valid node range is [0 - %d]",
>>                                        ^ should be a '.'
>>
>> And maybe need a '.' at the end of the second sentence too, as it's not
>> an error phrase, but a real sentence.
>>
>>> +                   MAX(src, dst), MAX_NODES - 1);
>>>          return;
>>>      }
>
> Actually, error_setg() is documented as taking a single phrase (no '.'
> included), and that if you need a second sentence, it's better to use
> error_append_hint().

Correct.  Providing help on valid values is exactly what
error_append_hint() is for.

>                       Maybe Markus has an opinion on the best way to
> word this error message.

Yes: "Parameter 'src' expects an integer between 0 and 127"

Referring to an erroneous key=value by value is not nice.  What if the
value occurs in multiple places, and is valid in at least one?  key is
there, it's unique[*], so use it.


[*] Except in the few places that use repeated keys to form lists.  Ugh.

Re: [Qemu-devel] [PATCH v2] numa: clarify error message when node index is out of range in -numa dist, ...

[Igor Mammedov]

On Tue, 15 May 2018 19:37:02 +0200
Markus Armbruster <armbru@redhat.com> wrote:

> Eric Blake <eblake@redhat.com> writes:
> 
> > On 05/15/2018 10:26 AM, Andrew Jones wrote:  
> >> On Tue, May 15, 2018 at 04:48:33PM +0200, Igor Mammedov wrote:  
> >>> When using following CLI:
> >>>    -numa dist,src=128,dst=1,val=20
> >>> user gets a rather confusing error message:
> >>>     "Invalid node 128, max possible could be 128"
> >>>
> >>> Where 128 is number of nodes that QEMU supports (MAX_NODES),
> >>> while src/dst is an index up to that limit, so it should be
> >>> MAX_NODES - 1 in error message.
> >>> Make error message to explicitly state valid range for node
> >>> index to be more clear.
> >>>
> >>> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> >>> Reviewed-by: Andrew Jones <drjones@redhat.com>
> >>> ---  
> >  
> >>>       if (src >= MAX_NODES || dst >= MAX_NODES) {
> >>>           error_setg(errp,
> >>> -                   "Invalid node %d, max possible could be %d",
> >>> -                   MAX(src, dst), MAX_NODES);
> >>> +                   "Invalid node %d, The valid node range is [0 - %d]",  
> >>                                        ^ should be a '.'
> >>
> >> And maybe need a '.' at the end of the second sentence too, as it's not
> >> an error phrase, but a real sentence.
> >>  
> >>> +                   MAX(src, dst), MAX_NODES - 1);
> >>>          return;
> >>>      }  
> >
> > Actually, error_setg() is documented as taking a single phrase (no '.'
> > included), and that if you need a second sentence, it's better to use
> > error_append_hint(). 
well, using append_hint makes it less readable, before using it we get following error:

$ qemu-system-x86_64 -numa dist,src=128,dst=1,val=20
qemu-system-x86_64: -numa dist,src=128,dst=1,val=20: Invalid node 128, The valid node range is [0 - 127]
$

after using it we get:
  
$ qemu-system-x86_64 -numa dist,src=128,dst=1,val=20
qemu-system-x86_64: -numa dist,src=128,dst=1,val=20: Invalid node value 128
The valid node range is [0 - 127]$ 

i.e. an extra newline in the middle of error message and looses automatic
newline at the end so the shell prompt continues error message


> Correct.  Providing help on valid values is exactly what
> error_append_hint() is for.
> 
> >                       Maybe Markus has an opinion on the best way to
> > word this error message.  
> 
> Yes: "Parameter 'src' expects an integer between 0 and 127"
> 
> Referring to an erroneous key=value by value is not nice.  What if the
> value occurs in multiple places, and is valid in at least one?  key is
> there, it's unique[*], so use it.
> 
> 
> [*] Except in the few places that use repeated keys to form lists.  Ugh.

Re: [Qemu-devel] [PATCH v2] numa: clarify error message when node index is out of range in -numa dist, ...

[Eric Blake]

On 05/16/2018 09:32 AM, Igor Mammedov wrote:
>>> Actually, error_setg() is documented as taking a single phrase (no '.'
>>> included), and that if you need a second sentence, it's better to use
>>> error_append_hint().
> well, using append_hint makes it less readable, before using it we get following error:
> 
> $ qemu-system-x86_64 -numa dist,src=128,dst=1,val=20
> qemu-system-x86_64: -numa dist,src=128,dst=1,val=20: Invalid node 128, The valid node range is [0 - 127]
> $
> 
> after using it we get:
>    
> $ qemu-system-x86_64 -numa dist,src=128,dst=1,val=20
> qemu-system-x86_64: -numa dist,src=128,dst=1,val=20: Invalid node value 128
> The valid node range is [0 - 127]$
> 
> i.e. an extra newline in the middle of error message and looses automatic
> newline at the end so the shell prompt continues error message
> 

Use of error_append_hint() requires you to provide a newline (unlike 
error_setg().  But as Markus pointed out, you don't need to use it:

> 
>> Correct.  Providing help on valid values is exactly what
>> error_append_hint() is for.
>>
>>>                        Maybe Markus has an opinion on the best way to
>>> word this error message.
>>
>> Yes: "Parameter 'src' expects an integer between 0 and 127"

I like this wording better, which avoids the shortfalls that 
error_append_hint() would introduce.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org