x86, alternative: Call stop_machine_text_poke() on all cpus

Currently, text_poke_smp() passes a NULL as the third argument to
__stop_machine(), which will only run stop_machine_text_poke()
on 1 cpu. Change NULL -> cpu_online_mask, as stop_machine_text_poke()
is intended to be run on all cpus.

I actually didn't notice any problems with stop_machine_text_poke()
only being called on 1 cpu, but found this via code inspection.
Signed-off-by: NJason Baron <jbaron@redhat.com>
LKML-Reference: <20101028152026.GB2875@redhat.com>
Acked-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

arch/x86/kernel/alternative.c

@@ -638,7 +638,7 @@ void *__kprobes text_poke_smp(void *addr, const void *opcode, size_t len)
 	atomic_set(&stop_machine_first, 1);
 	wrote_text = 0;
 	/* Use __stop_machine() because the caller already got online_cpus. */
-	__stop_machine(stop_machine_text_poke, (void *)&tpp, NULL);
+	__stop_machine(stop_machine_text_poke, (void *)&tpp, cpu_online_mask);
 	return addr;
 }