linux-kernel - Re: [PATCH] creds: suppress warning in get

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Date:	Mon, 19 Jan 2009 15:59:00 +0100
From:	"Hannes Eder" <hannes@...neseder.net>
To:	"Stephen Rothwell" <sfr@...b.auug.org.au>
Cc:	"David Howells" <dhowells@...hat.com>,
	"James Morris" <jmorris@...ei.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] creds: suppress warning in get_cred

On Mon, Jan 19, 2009 at 3:52 PM, Stephen Rothwell <sfr@...b.auug.org.au> wrote:
> Hi David,
>
> On Mon, 19 Jan 2009 12:29:31 +0000 David Howells <dhowells@...hat.com> wrote:
>>
>> Stephen Rothwell <sfr@...b.auug.org.au> wrote:
>>
>> > +   return get_new_cred((struct cred *)(uintptr_t)cred);
>>
>> That should probably be 'unsigned long' within the kernel.  This is also a
>> compiler bug, but I think we can live with this fix.
>
> We do have uintptr_t inside the kernel (it is typedeffed to unsigned
> long) but I used it explicitly because its type is defined to be large
> enough to store any pointer.

When working around this compiler bug would it be better to do it like this:

+     return get_new_cred((struct cred *)(void *)cred);

instead of relying on the size of a pointer and using an large enough
integer data type?

Maybe would should just add a comment, to note that if such a warning
is issued, that
this is a compiler bug.

Or disable the warning for this region, but as far as I know gcc _does
not_ have this feature yet.

> However, I have also verified that using a newer compiler (4.3.2 in my
> case) makes the warning go away as Hannes Eder pointed out when
> mentioning his earlier patch.

Hannes
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