Re: [patch 12/18] ptrace, treewide: Rename ptrace_report_syscall_entry() to ptrace_report_syscall_permit_entry()

[Oleg Nesterov <oleg@redhat.com>]

On 07/10, Michal Suchánek wrote:
>
> > --- a/arch/alpha/kernel/ptrace.c
> > +++ b/arch/alpha/kernel/ptrace.c
> > @@ -375,7 +375,7 @@ asmlinkage unsigned long syscall_trace_e
> >  	struct pt_regs *regs = current_pt_regs();
> >
> >  	if (test_thread_flag(TIF_SYSCALL_TRACE) &&
> > -		ptrace_report_syscall_entry(regs)) {
> > +		!ptrace_report_syscall_permit_entry(regs)) {
> >  		syscall_set_nr(current, regs, -1);
>
> Why is this done here?
>
> Presumably the ptrace_report_syscall_entry returns false here becasue
> the tracer put -1 into whatever register specifies the syscall number
> (or it was there to start with) which was then read back, compared to
> -1, leading to returning false.  Now it's set to -1 again?

I don't know why arch/alpha/ does syscall_set_nr(-1).

But note that ptrace_report_syscall_entry() doesn't even check whether
the syscall number was changed. It only checks fatal_signal_pending().

Oleg.