Messages in this thread | | | Date | Tue, 8 Sep 2015 18:06:52 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH 1/5] tools: Add err.h with ERR_PTR PTR_ERR interface |
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Em Tue, Sep 08, 2015 at 04:22:39PM -0400, Raphaël Beamonte escreveu: > 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 > > > > 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 > > Perhaps a dumb question, but it seems the code is exactly the same as > in linux/err.h besides the part of the comment you added. Why not > using that file directly in the other patches then?
We can't do that.
Read:
commit 3f735377bfd6567d80815a6242c147211963680a Author: Arnaldo Carvalho de Melo <acme@redhat.com> Date: Sun Jul 5 22:48:21 2015 -0300
tools: Copy lib/rbtree.c to tools/lib/
So that we can remove kernel specific stuff we've been stubbing out via a tools/include/linux/export.h that gets removed in this patch and to avoid breakages in the future like the one fixed recently where rcupdate.h started being used in rbtree.h.
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There are more copies like that, but the explanation above should be enough, no?
- Arnaldo
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