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

From: Johannes Weiner
Date: Mon May 19 2008 - 08:11:53 EST


Hi,

Alexey Dobriyan <adobriyan@xxxxxxxxx> writes:

> 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 ?

Well, okay. Perhaps ratelimiting? I really prefer a bigger image size
over a spammed dmesg.

Hannes
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