arch/x86/kernel/kdebugfs.c: Ensure a consistent return value in error case

arch/x86/kernel/kdebugfs.c: Ensure a consistent return value in error case

Typically, the return value desired for the failure of a
function with an integer return value is a negative integer.  In
these cases, the return value is sometimes a negative integer
and sometimes 0, due to a subsequent initialization of the
return variable within the loop.

A simplified version of the semantic match that finds this
problem is: (http://coccinelle.lip6.fr/)

//<smpl>
@r exists@
identifier ret;
position p;
constant C;
expression e1,e3,e4;
statement S;
@@

ret = -C
... when != ret = e3
    when any
if@p (...) S
... when any
if (\(ret != 0\|ret < 0\|ret > 0\) || ...) { ... return ...; }
... when != ret = e3
    when any
*if@p (...)
{
  ... when != ret = e4
  return ret;
}
//</smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Link: http://lkml.kernel.org/r/1342284188-19176-7-git-send-email-Julia.Lawall@lip6.fr
Signed-off-by: Ingo Molnar <mingo@kernel.org>