Re: [PATCH 6/6] ERR_PTR: warn when ERR_PTR parameter is not errnovalue

[Alexey Dobriyan]

On Mon, May 19, 2008 at 01:13:20AM +0200, Johannes Weiner wrote:
> Marcin Slusarz <marcin.slusarz@xxxxxxxxx> writes:
> 
> > Check at runtime whether error argument of ERR_PTR and ERR_OR_0_PTR
> > is valid. It can catch bugs which possibly lead to oops or panic earlier.
> >
> > Currently there are > 600 calls of ERR_PTR with non-constant argument
> > in Linux kernel sources.

> > --- a/include/linux/err.h
> > +++ b/include/linux/err.h
> > @@ -3,6 +3,7 @@
> >  
> >  #include <linux/compiler.h>
> >  
> > +#include <asm/bug.h>
> >  #include <asm/errno.h>
> >  
> >  /*
> > @@ -21,6 +22,7 @@
> >  
> >  static inline void *__ERR_PTR(long error)
> >  {
> > +	WARN_ON(!IS_ERR_VALUE(error));
> >  	return (void *) error;
> >  }
> >  
> > @@ -28,6 +30,7 @@ static inline void *__ERR_PTR(long error)
> >  
> >  static inline void *__ERR_OR_0_PTR(long error)
> >  {
> > +	WARN_ON(!IS_ERR_VALUE(error) && error);
> >  	return (void *) error;
> >  }
> 
> How about WARN_ON_ONCE() instead?  That would warn once for each erroneous user
> which should be enough.

And blow up .bss ?

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