linux-kernel - [RFC v0 4/9] smpboot: Use freeze_active() instead CPU_DEAD

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Date:	Fri,  4 Sep 2015 15:34:57 +0200
From:	Daniel Wagner <daniel.wagner@...-carit.de>
To:	linux-kernel@...r.kernel.org
Cc:	Daniel Wagner <daniel.wagner@...-carit.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Chris Metcalf <cmetcalf@...hip.com>,
	Don Zickus <dzickus@...hat.com>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Peter Zijlstra <peterz@...radead.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [RFC v0 4/9] smpboot: Use freeze_active() instead CPU_DEAD_FROZEN state information

In order to get rid of all CPU_*_FROZEN states we need to convert all
users first.

cpu_check_up_prepare() wants to report different errors depending on
an ongoing suspend or not. freeze_active() reports back if that is the
case so we don't have to rely on the CPU_DEAD_FROZEN anymore.

Signed-off-by: Daniel Wagner <daniel.wagner@...-carit.de>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Chris Metcalf <cmetcalf@...hip.com>
Cc: Don Zickus <dzickus@...hat.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Lai Jiangshan <laijs@...fujitsu.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc: linux-kernel@...r.kernel.org
---
 kernel/smpboot.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/kernel/smpboot.c b/kernel/smpboot.c
index e37efbf..49ce4e9 100644
--- a/kernel/smpboot.c
+++ b/kernel/smpboot.c
@@ -13,6 +13,7 @@
 #include <linux/percpu.h>
 #include <linux/kthread.h>
 #include <linux/smpboot.h>
+#include <linux/suspend.h>
 
 #include "smpboot.h"
 
@@ -407,26 +408,25 @@ int cpu_check_up_prepare(int cpu)
 	switch (atomic_read(&per_cpu(cpu_hotplug_state, cpu))) {
 
 	case CPU_POST_DEAD:
+		if (freeze_active()) {
+			/*
+			 * Timeout during CPU death, so let caller know.
+			 * The outgoing CPU completed its processing, but after
+			 * cpu_wait_death() timed out and reported the error. The
+			 * caller is free to proceed, in which case the state
+			 * will be reset properly by cpu_set_state_online().
+			 * Proceeding despite this -EBUSY return makes sense
+			 * for systems where the outgoing CPUs take themselves
+			 * offline, with no post-death manipulation required from
+			 * a surviving CPU.
+			 */
+			return -EBUSY;
+		}
 
 		/* The CPU died properly, so just start it up again. */
 		atomic_set(&per_cpu(cpu_hotplug_state, cpu), CPU_UP_PREPARE);
 		return 0;
 
-	case CPU_DEAD_FROZEN:
-
-		/*
-		 * Timeout during CPU death, so let caller know.
-		 * The outgoing CPU completed its processing, but after
-		 * cpu_wait_death() timed out and reported the error. The
-		 * caller is free to proceed, in which case the state
-		 * will be reset properly by cpu_set_state_online().
-		 * Proceeding despite this -EBUSY return makes sense
-		 * for systems where the outgoing CPUs take themselves
-		 * offline, with no post-death manipulation required from
-		 * a surviving CPU.
-		 */
-		return -EBUSY;
-
 	case CPU_BROKEN:
 
 		/*
-- 
2.4.3

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