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    SubjectRe: The sheer number of sparse warnings in the kernel
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    On Wed, 2014-02-26 at 14:49 -0800, H. Peter Anvin wrote:
    > The number of sparse errors in the current kernel is staggering, and it
    > makes sparse a lot less valuable of a tool that it otherwise could be.
    > On a build of x86-64 allyesconfig I'm getting 20,676 sparse messages.
    > Out of those, 12,358 come from linux/err.h. Given that the latter
    > basically spams *everything*, I can only conclude that almost noone uses
    > sparse unless they have a filter script.
    >
    > So a lot of these are certainly nuisance problems, like the
    > <linux/err.h> stuff which has to do with the handling of error values,
    > but some of these look like real bugs.
    >
    > What do we need to do to actually make our tools be able to do work for
    > us? Newbie projects to clean up? Trying to get the larger Linux
    > companies to put resources on it?

    gcc 4.8 does annoyingly warn on all unsigned/signed
    mismatches/implicit conversions too.

    err.h could also return bool instead of long for the
    IS_ERR and IS_ERR_OR_NULL tests.

    Maybe something like this could be useful.

    Shut up the unsigned<->signed pointer conversions
    and implicit conversions in the Makefile.

    Use bool not long for IS_ERR and IS_ERR_OR_NULL

    Update the dentry description of kernel pointers
    left over from 2002's move to err.h

    unsigned...

    ---
    Makefile | 1 +
    include/linux/err.h | 7 ++++---
    2 files changed, 5 insertions(+), 3 deletions(-)

    diff --git a/Makefile b/Makefile
    index fce2ba7..a9c11c4 100644
    --- a/Makefile
    +++ b/Makefile
    @@ -381,6 +381,7 @@ KBUILD_CPPFLAGS := -D__KERNEL__
    KBUILD_CFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
    -fno-strict-aliasing -fno-common \
    -Werror-implicit-function-declaration \
    + -Wno-sign-conversion -Wno-pointer-sign \
    -Wno-format-security \
    -fno-delete-null-pointer-checks
    KBUILD_AFLAGS_KERNEL :=
    diff --git a/include/linux/err.h b/include/linux/err.h
    index 15f92e0..a729120 100644
    --- a/include/linux/err.h
    +++ b/include/linux/err.h
    @@ -2,12 +2,13 @@
    #define _LINUX_ERR_H

    #include <linux/compiler.h>
    +#include <linux/types.h>

    #include <asm/errno.h>

    /*
    * Kernel pointers have redundant information, so we can use a
    - * scheme where we can return either an error code or a dentry
    + * scheme where we can return either an error code or a normal
    * pointer with the same return value.
    *
    * This should be a per-architecture thing, to allow different
    @@ -29,12 +30,12 @@ static inline long __must_check PTR_ERR(__force const void *ptr)
    return (long) ptr;
    }

    -static inline long __must_check IS_ERR(__force const void *ptr)
    +static inline bool __must_check IS_ERR(__force const void *ptr)
    {
    return IS_ERR_VALUE((unsigned long)ptr);
    }

    -static inline long __must_check IS_ERR_OR_NULL(__force const void *ptr)
    +static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
    {
    return !ptr || IS_ERR_VALUE((unsigned long)ptr);
    }



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