Re: [Xen-devel] [PATCH v3 39/52] xen: check parameter validity when parsing command line

[Juergen Gross <jgross@xxxxxxxx>]

On 23/08/17 11:38, Jan Beulich wrote:
>>>> On 23.08.17 at 11:30, <jgross@xxxxxxxx> wrote:
>> On 22/08/17 13:24, Jan Beulich wrote:
>>>>>> On 16.08.17 at 14:52, <jgross@xxxxxxxx> wrote:
>>>> @@ -176,7 +210,8 @@ int __init parse_bool(const char *s)
>>>>           !strcmp("on", s) ||
>>>>           !strcmp("true", s) ||
>>>>           !strcmp("enable", s) ||
>>>> -         !strcmp("1", s) )
>>>> +         !strcmp("1", s) ||
>>>> +         !*s )
>>>>          return 1;
>>>
>>> Careful with this: Taking the "iommu=" example that I've commented
>>> on in the other patch already, much depends on what you mean to
>>> do about the problem there: "iommu=,..." should not end up
>>> meaning "iommu=on,...".
>>
>> It won't. *s will be ',' in this case.
> 
> Right, but as said - much depends on what you mean to do about
> the problem in the earlier patch.

So I just hit this. And looking more thoroughly into it: today it in
fact has exactly this meaning. iommu_enable is "1" per default. So
specifying "iommu=,..." won't change this and has the same semantics
as "iommu=on,...".

So should I change this or not? With the new parse_bool() parameter
(end of the string pointer or NULL) I can easily tell the difference
between a boolean with or without following options.


Juergen

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