Re: [PATCH] ptrace/x86: introduce TS_COMPAT_RESTART to fix get_nr_restart_syscall()

[Oleg Nesterov]

On 11/28, Linus Torvalds wrote:
>
> > --- a/arch/x86/include/asm/signal.h
> > +++ b/arch/x86/include/asm/signal.h
> > @@ -5,6 +5,10 @@
> >  #ifndef __ASSEMBLY__
> >  #include <linux/linkage.h>
> >
> > +struct restart_block;
> > +extern void arch_set_restart_data(struct restart_block *);
> > +#define arch_set_restart_data  arch_set_restart_data
> 
> I'd just replace this with
> 
>    /* We need to save TS_COMPAT at the time of the call */
>    #define arch_set_restart_data(blk) (blk)->arch_data =
> current_thread_info()->status

OK, but then this code should live in {linux,asm}/thread_info.h. And this
is probably better, linux/thread_info.h already includes restart_block.h.

What do you think about 1-4 below?

Please note that 3/4 adds TS_COMPAT_RESTART you do not like, 4/4 kills it
and adds restart_block->arch_data.

This is because I will need to backport this fix, and 4/4 is not trivially
backportable due to KABI issues.

Oleg.