Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH v3] err.h: allow IS_ERR_VALUE to handle properly more types | Date | Thu, 11 Feb 2016 17:39:49 +0100 |
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On Thursday 11 February 2016 08:00:54 Andrzej Hajda wrote: > > I think the easiest way to express this would be to ensure that the argument > > is 'unsigned long', like: > > > > #define IS_ERR_VALUE(x) ((unsigned long*)NULL == (typeof (x)*)NULL && \ > > unlikely((unsigned long long)(x) >= (unsigned long long)(typeof(x))-MAX_ERRNO)) > > This way you will limit it only to unsigned long type, which seems too > strict to me. > I think the macro should accept all long enough unsigned types, otherwise we > could end up with bunch of macros IS_ERR_VALUE_U32, IS_ERR_VALUE_ULL...
I think in practice we only care about 'int' and 'unsigned long', which are the ones that 90% of the existing users pass in today. u32 has never worked on 64-bit architectures so far, so we don't necessarily have to make it work. As Al mentioned, most users of IS_ERR_VALUE are wrong anyway and should just use 'if (err < 0)' or 'if (err)'.
We could also consider making just 'int' and 'unsigned long' allowed types for the moment, and then change all users passing 'int' before forbidding them.
Arnd
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