Re: [PATCH] exec: Remove the duplicated check in parse_cpu_option()

[Gavin Shan <gshan@redhat.com>]

On 12/7/19 3:58 AM, Greg Kurz wrote:
> On Fri,  6 Dec 2019 17:33:37 +1100
> Gavin Shan <gshan@redhat.com> wrote:
> 
>> The @cpu_option shouldn't be NULL, otherwise assertion from g_strsplit()
>> should be raised as below message indicates. So it's meaningless to validate
>> @model_pices[0] in parse_cpu_option() as it shouldn't be NULL either.
>>
>>     qemu-system-aarch64: GLib: g_strsplit: assertion 'string != NULL' failed
>>
>> This just removes the check and unused message.
>>
> 
> Hrm... the check isn't about @cpu_option being NULL. It is about filtering out
> invalid syntaxes like:
> 
> -cpu ''
> 
> or
> 
> -cpu ,some-prop
> 

Greg, Thanks for your review on this trivial patch.

@cpu_option[0] is NULL when we have "-cpu ''". We run into assertion raised
by subsequent cpu_class_by_name(). However, @cpu_option[0] isn't NULL with
something like "-cpu ,xxx", but the CPU model specific class can't be found
at last.

So the validation mostly relies on cpu_class_by_name() if I'm correct. It's
fine to remove the check. However, it provides explicit error message, which
isn't bad though:

    error_report("-cpu option cannot be empty");

>> Signed-off-by: Gavin Shan <gshan@redhat.com>
>> ---
>>   exec.c | 5 -----
>>   1 file changed, 5 deletions(-)
>>
>> diff --git a/exec.c b/exec.c
>> index ffdb518535..3cff459e43 100644
>> --- a/exec.c
>> +++ b/exec.c
>> @@ -963,11 +963,6 @@ const char *parse_cpu_option(const char *cpu_option)
>>       const char *cpu_type;
>>   
>>       model_pieces = g_strsplit(cpu_option, ",", 2);
>> -    if (!model_pieces[0]) {
>> -        error_report("-cpu option cannot be empty");
>> -        exit(1);
>> -    }
>> -
>>       oc = cpu_class_by_name(CPU_RESOLVING_TYPE, model_pieces[0]);
>>       if (oc == NULL) {
>>           error_report("unable to find CPU model '%s'", model_pieces[0]);
> 

Regards,
Gavin