From: Andrew Morton <akpm@linux-foundation.org>
Date: Thu, 22 May 2014 00:44:05 +0000 (+1000)
Subject: smp-print-more-useful-debug-info-upon-receiving-ipi-on-an-offline-cpu-fix
X-Git-Tag: next-20140530~2^2~63
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=ff3b5849fc1447f8e2e424fb71bf2d6f119f580f;p=karo-tx-linux.git

smp-print-more-useful-debug-info-upon-receiving-ipi-on-an-offline-cpu-fix

correctly suppress warning output on second and later occurrences

Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Gautham R Shenoy <ego@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <mgalbraith@suse.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Rik van Riel <riel@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/kernel/smp.c b/kernel/smp.c
index 6cb0e2ef9fe9..f864921fc82c 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -185,20 +185,17 @@ void generic_smp_call_function_single_interrupt(void)
 {
 	struct llist_node *entry;
 	struct call_single_data *csd, *csd_next;
-	int warn = 0;
-
-	/*
-	 * Shouldn't receive this interrupt on a cpu that is not yet online.
-	 */
-	if (unlikely(!cpu_online(smp_processor_id()))) {
-		warn = 1;
-		WARN_ON_ONCE(1);
-	}
+	static bool warned;
 
 	entry = llist_del_all(&__get_cpu_var(call_single_queue));
 	entry = llist_reverse_order(entry);
 
-	if (unlikely(warn)) {
+	/*
+	 * Shouldn't receive this interrupt on a cpu that is not yet online.
+	 */
+	if (unlikely(!cpu_online(smp_processor_id()) && !warned)) {
+		warned = true;
+		WARN_ON(1);
 		/*
 		 * We don't have to use the _safe() variant here
 		 * because we are not invoking the IPI handlers yet.