Messages in this thread | | | Date | Fri, 12 Mar 2010 21:45:17 +0200 | From | Phil Carmody <> | Subject | Re: [PATCH] err.h: add __must_check to error pointer handlers |
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On 12/03/10 19:40 +0100, ext Alexey Dobriyan wrote: > On Fri, Mar 12, 2010 at 03:45:40PM +0200, Jani Nikula wrote: > > Add __must_check to error pointer handlers to have the compiler warn > > about mistakes like: > > > > if (err) > > ERR_PTR(err); > > > -static inline void *ERR_PTR(long error) > > +static inline void * __must_check ERR_PTR(long error) > > We had bugs like that?
Two popped out immediately. Patches have been sent to appropriate maintainers. Grepping my inbox:
Mar 12 Nikula Jani [PATCH] enclosure: fix error path - actually return ERR_PTR() on error Mar 12 Nikula Jani [PATCH] sunrpc: fix error path - actually return ERR_PTR() on error
There's a slim chance that there may be others (grep doesn't find any more obvious ones), but as allmodconfig seems broken currently, there may be others which are as yet undiscovered.
> Pretty much every non-void function should be marked then.
All functions where it makes no sense ignore the return value. You really wouldn't be doing an ERR_PTR unless you wanted to use the result.
Note that __must_check doesn't actually require 'checking', merely 'using' the return value, which includes just storing it in a variable, and then later ignoring it.
An alternative static code analysis method could be used to detect such things. Coverity Prevent uses a heuristic algorithm to detect missing checks of return values using a popularity contest. Most people check it - then everyone should probably check it.
Phil
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