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SubjectRe: [PATCH 6/6] ERR_PTR: warn when ERR_PTR parameter is not errno value
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Hi Marcin,

Marcin Slusarz <marcin.slusarz@gmail.com> 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.
>
> Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> ---
> include/linux/err.h | 3 +++
> 1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/err.h b/include/linux/err.h
> index cdec8b6..51e2459 100644
> --- 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.

Hannes


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