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    SubjectRe: [PATCH 1/5] tools: Add err.h with ERR_PTR PTR_ERR interface
    2015-09-07 4:38 GMT-04:00 Jiri Olsa <jolsa@kernel.org>:
    > Adding part of the kernel's <linux/err.h> interface:
    > inline void * __must_check ERR_PTR(long error);
    > inline long __must_check PTR_ERR(__force const void *ptr);
    > inline bool __must_check IS_ERR(__force const void *ptr);
    >
    > it will be used to propagate error through pointers
    > in following patches.
    >
    > Link: http://lkml.kernel.org/n/tip-ufgnyf683uab69anmmrabgdf@git.kernel.org
    > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
    > ---
    > tools/include/linux/err.h | 49 +++++++++++++++++++++++++++++++++++++++++++++++
    > 1 file changed, 49 insertions(+)
    > create mode 100644 tools/include/linux/err.h

    Reviewed-by: Raphaël Beamonte <raphael.beamonte@gmail.com>

    >
    > diff --git a/tools/include/linux/err.h b/tools/include/linux/err.h
    > new file mode 100644
    > index 000000000000..c9ada48f5156
    > --- /dev/null
    > +++ b/tools/include/linux/err.h
    > @@ -0,0 +1,49 @@
    > +#ifndef __TOOLS_LINUX_ERR_H
    > +#define __TOOLS_LINUX_ERR_H
    > +
    > +#include <linux/compiler.h>
    > +#include <linux/types.h>
    > +
    > +#include <asm/errno.h>
    > +
    > +/*
    > + * Original kernel header comment:
    > + *
    > + * Kernel pointers have redundant information, so we can use a
    > + * 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
    > + * error and pointer decisions.
    > + *
    > + * Userspace note:
    > + * The same principle works for userspace, because 'error' pointers
    > + * fall down to the unused hole far from user space, as described
    > + * in Documentation/x86/x86_64/mm.txt for x86_64 arch:
    > + *
    > + * 0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm hole caused by [48:63] sign extension
    > + * ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole
    > + *
    > + * It should be the same case for other architectures, because
    > + * this code is used in generic kernel code.
    > + */
    > +#define MAX_ERRNO 4095
    > +
    > +#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)
    > +
    > +static inline void * __must_check ERR_PTR(long error)
    > +{
    > + return (void *) error;
    > +}
    > +
    > +static inline long __must_check PTR_ERR(__force const void *ptr)
    > +{
    > + return (long) ptr;
    > +}
    > +
    > +static inline bool __must_check IS_ERR(__force const void *ptr)
    > +{
    > + return IS_ERR_VALUE((unsigned long)ptr);
    > +}
    > +
    > +#endif /* _LINUX_ERR_H */
    > --
    > 2.4.3
    >


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