Re: + uapi-fix-linux-sysctlh-userspace-compilation-errors.patch added to -mm tree

[Dmitry V. Levin]

On Fri, Feb 24, 2017 at 05:35:33PM +0300, Alexey Dobriyan wrote:
> On Thu, Feb 23, 2017 at 02:44:31PM -0800, akpm@xxxxxxxxxxxxxxxxxxxx wrote:
> > /usr/include/linux/sysctl.h:38:2: error: unknown type name 'size_t'
> >   size_t *oldlenp;
> > /usr/include/linux/sysctl.h:40:2: error: unknown type name 'size_t'
> >   size_t newlen;
> 
> > --- a/include/uapi/linux/sysctl.h~uapi-fix-linux-sysctlh-userspace-compilation-errors
> > +++ a/include/uapi/linux/sysctl.h
> > @@ -26,6 +26,10 @@
> >  #include <linux/types.h>
> >  #include <linux/compiler.h>
> >  
> > +#ifndef __KERNEL__
> > +#include <stddef.h>		/* For size_t. */
> > +#endif
> 
> There is __kernel_size_t for cases like this.

No, __kernel_size_t is not for cases like this because size_t differs
from __kernel_size_t on x32 and mips n32.

Fortunately, there is no sysctl syscall entry on x32, but on mips m32
it is there with number 6152, implemented using compat_sys_sysctl.
The latter operates with argument of type struct compat_sysctl_args*
where newlen is of type compat_size_t.

If you change it from size_t to __kernel_size_t, you'll break mips n32.


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