linux-kernel - Re: [next:akpm 798/1000] drivers/rtc/rtc-ds1286.c:343:24: sparse: incorrect type in argument 1 (different address spaces)

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Message-ID: <20130423061600.GN6638@mwanda>
Date:	Tue, 23 Apr 2013 09:16:00 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Christopher Li <sparse@...isli.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	kbuild test robot <fengguang.wu@...el.com>,
	Jingoo Han <jg1.han@...sung.com>, kbuild-all@...org,
	Linux-Sparse <linux-sparse@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [next:akpm 798/1000] drivers/rtc/rtc-ds1286.c:343:24: sparse:
 incorrect type in argument 1 (different address spaces)

On Mon, Apr 22, 2013 at 07:56:19PM -0700, Christopher Li wrote:
> On Mon, Apr 22, 2013 at 4:56 PM, Andrew Morton
> <akpm@...ux-foundation.org> wrote:
> > I think doing IS_ERR() and PTR_ERR() on __iomem pointers is a natural
> > thing, and we should be able to do this without adding call-site
> > trickery to make sparse happy.
> >
> > Is there some sort of annotation which we can add to the
> > IS_ERR()/PTR_ERR() definitions so that sparse will stop warning about
> > this usage?
> 
> Yes, the force attribute should silent the address check on conversion.
> 
> Can some one try this patch (totally untested).
> 

That didn't work.  It's the the void * in the parameter list that's
the problem.  We'd need to do something like the patch below:

Otherwise we could add "__ok_to_cast" thing to Sparse maybe?

regards,
dan carpenter

diff --git a/include/linux/err.h b/include/linux/err.h
index f2edce2..2cbe8fb 100644
--- a/include/linux/err.h
+++ b/include/linux/err.h
@@ -24,20 +24,23 @@ static inline void * __must_check ERR_PTR(long error)
 	return (void *) error;
 }
 
-static inline long __must_check PTR_ERR(const void *ptr)
+static inline long __must_check _PTR_ERR(const void *ptr)
 {
 	return (long) ptr;
 }
+#define PTR_ERR(x) _PTR_ERR((const void __force *)(x))
 
-static inline long __must_check IS_ERR(const void *ptr)
+static inline long __must_check _IS_ERR(const void *ptr)
 {
 	return IS_ERR_VALUE((unsigned long)ptr);
 }
+#define IS_ERR(x) _IS_ERR((const void __force *)(x))
 
-static inline long __must_check IS_ERR_OR_NULL(const void *ptr)
+static inline long __must_check _IS_ERR_OR_NULL(const void *ptr)
 {
 	return !ptr || IS_ERR_VALUE((unsigned long)ptr);
 }
+#define IS_ERR_OR_NULL(x) _IS_ERR_OR_NULL((const void __force *)(x))
 
 /**
  * ERR_CAST - Explicitly cast an error-valued pointer to another pointer type
@@ -46,19 +49,21 @@ static inline long __must_check IS_ERR_OR_NULL(const void *ptr)
  * Explicitly cast an error-valued pointer to another pointer type in such a
  * way as to make it clear that's what's going on.
  */
-static inline void * __must_check ERR_CAST(const void *ptr)
+static inline void * __must_check _ERR_CAST(const void *ptr)
 {
 	/* cast away the const */
 	return (void *) ptr;
 }
+#define ERR_CAST(x) _ERR_CAST((const void __force *)(x))
 
-static inline int __must_check PTR_RET(const void *ptr)
+static inline int __must_check _PTR_RET(const void *ptr)
 {
 	if (IS_ERR(ptr))
 		return PTR_ERR(ptr);
 	else
 		return 0;
 }
+#define PTR_RET(x) _PTR_RET((const void __force *)(x))
 
 #endif
 
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