[PATCH] stack overflow safe kdump: safe smp_send_nmi_allbutself()

Re-implement smp_send_nmi_allbutself() so that calls to smp_processor_id
(through send_IPI_allbutself) can be replaced with safe_smp_processor_id
without affecting other parts of the kernel (as suggested by Eric Biederman).
Signed-off-by: NFernando Vazquez <fernando@intellilink.co.jp>
Looks-reasonable-to: Andi Kleen <ak@muc.de>
Acked-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@in.ibm.com>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

arch/i386/kernel/crash.c

@@ -134,7 +134,10 @@ static int crash_nmi_callback(struct notifier_block *self,
 
 static void smp_send_nmi_allbutself(void)
 {
-	send_IPI_allbutself(NMI_VECTOR);
+	cpumask_t mask = cpu_online_map;
+	cpu_clear(safe_smp_processor_id(), mask);
+	if (!cpus_empty(mask))
+		send_IPI_mask(mask, NMI_VECTOR);
 }
 
 static struct notifier_block crash_nmi_nb = {