s390/kernel: Fix smp_call_ipl_cpu() for offline CPUs

static void pcpu_delegate(struct pcpu *pcpu, void (*func)(void *),

			  void *data, unsigned long stack)

{

	struct _lowcore *lc = pcpu->lowcore;

	unsigned short this_cpu;

	struct _lowcore *lc = lowcore_ptr[pcpu - pcpu_devices];

	struct {

		unsigned long	stack;

		void		*func;

		void		*data;

		unsigned long	source;

	} restart = { stack, func, data, stap() };

	__load_psw_mask(psw_kernel_bits);

	this_cpu = stap();

	if (pcpu->address == this_cpu)

	if (pcpu->address == restart.source)

		func(data);	/* should not return */

	/* Stop target cpu (if func returns this stops the current cpu). */

	pcpu_sigp_retry(pcpu, sigp_stop, 0);

	/* Restart func on the target cpu and stop the current cpu. */

	lc->restart_stack = stack;

	lc->restart_fn = (unsigned long) func;

	lc->restart_data = (unsigned long) data;

	lc->restart_source = (unsigned long) this_cpu;

	memcpy_absolute(&lc->restart_stack, &restart, sizeof(restart));

	asm volatile(

		"0:	sigp	0,%0,6	# sigp restart to target cpu\n"

		"	brc	2,0b	# busy, try again\n"

		"1:	sigp	0,%1,5	# sigp stop to current cpu\n"

		"	brc	2,1b	# busy, try again\n"

		: : "d" (pcpu->address), "d" (this_cpu) : "0", "1", "cc");

		: : "d" (pcpu->address), "d" (restart.source) : "0", "1", "cc");

	for (;;) ;

}