3.1-stable patches

added patches:
	pm-sleep-fix-race-between-cpu-hotplug-and-freezer.patch

diff --git a/queue-3.1/pm-sleep-fix-race-between-cpu-hotplug-and-freezer.patch b/queue-3.1/pm-sleep-fix-race-between-cpu-hotplug-and-freezer.patch
new file mode 100644 (file)
index 0000000..412f317
--- /dev/null
+++ b/queue-3.1/pm-sleep-fix-race-between-cpu-hotplug-and-freezer.patch
@@ -0,0 +1,125 @@
+From 79cfbdfa87e84992d509e6c1648a18e1d7e68c20 Mon Sep 17 00:00:00 2001
+From: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
+Date: Thu, 3 Nov 2011 00:59:25 +0100
+Subject: PM / Sleep: Fix race between CPU hotplug and freezer
+
+From: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
+
+commit 79cfbdfa87e84992d509e6c1648a18e1d7e68c20 upstream.
+
+The CPU hotplug notifications sent out by the _cpu_up() and _cpu_down()
+functions depend on the value of the 'tasks_frozen' argument passed to them
+(which indicates whether tasks have been frozen or not).
+(Examples for such CPU hotplug notifications: CPU_ONLINE, CPU_ONLINE_FROZEN,
+CPU_DEAD, CPU_DEAD_FROZEN).
+
+Thus, it is essential that while the callbacks for those notifications are
+running, the state of the system with respect to the tasks being frozen or
+not remains unchanged, *throughout that duration*. Hence there is a need for
+synchronizing the CPU hotplug code with the freezer subsystem.
+
+Since the freezer is involved only in the Suspend/Hibernate call paths, this
+patch hooks the CPU hotplug code to the suspend/hibernate notifiers
+PM_[SUSPEND|HIBERNATE]_PREPARE and PM_POST_[SUSPEND|HIBERNATE] to prevent
+the race between CPU hotplug and freezer, thus ensuring that CPU hotplug
+notifications will always be run with the state of the system really being
+what the notifications indicate, _throughout_ their execution time.
+
+Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
+Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
+Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
+
+---
+ kernel/cpu.c |   74 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ 1 file changed, 74 insertions(+)
+
+--- a/kernel/cpu.c
++++ b/kernel/cpu.c
+@@ -15,6 +15,7 @@
+ #include <linux/stop_machine.h>
+ #include <linux/mutex.h>
+ #include <linux/gfp.h>
++#include <linux/suspend.h>
+ 
+ #ifdef CONFIG_SMP
+ /* Serializes the updates to cpu_online_mask, cpu_present_mask */
+@@ -476,6 +477,79 @@ static int alloc_frozen_cpus(void)
+       return 0;
+ }
+ core_initcall(alloc_frozen_cpus);
++
++/*
++ * Prevent regular CPU hotplug from racing with the freezer, by disabling CPU
++ * hotplug when tasks are about to be frozen. Also, don't allow the freezer
++ * to continue until any currently running CPU hotplug operation gets
++ * completed.
++ * To modify the 'cpu_hotplug_disabled' flag, we need to acquire the
++ * 'cpu_add_remove_lock'. And this same lock is also taken by the regular
++ * CPU hotplug path and released only after it is complete. Thus, we
++ * (and hence the freezer) will block here until any currently running CPU
++ * hotplug operation gets completed.
++ */
++void cpu_hotplug_disable_before_freeze(void)
++{
++      cpu_maps_update_begin();
++      cpu_hotplug_disabled = 1;
++      cpu_maps_update_done();
++}
++
++
++/*
++ * When tasks have been thawed, re-enable regular CPU hotplug (which had been
++ * disabled while beginning to freeze tasks).
++ */
++void cpu_hotplug_enable_after_thaw(void)
++{
++      cpu_maps_update_begin();
++      cpu_hotplug_disabled = 0;
++      cpu_maps_update_done();
++}
++
++/*
++ * When callbacks for CPU hotplug notifications are being executed, we must
++ * ensure that the state of the system with respect to the tasks being frozen
++ * or not, as reported by the notification, remains unchanged *throughout the
++ * duration* of the execution of the callbacks.
++ * Hence we need to prevent the freezer from racing with regular CPU hotplug.
++ *
++ * This synchronization is implemented by mutually excluding regular CPU
++ * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
++ * Hibernate notifications.
++ */
++static int
++cpu_hotplug_pm_callback(struct notifier_block *nb,
++                      unsigned long action, void *ptr)
++{
++      switch (action) {
++
++      case PM_SUSPEND_PREPARE:
++      case PM_HIBERNATION_PREPARE:
++              cpu_hotplug_disable_before_freeze();
++              break;
++
++      case PM_POST_SUSPEND:
++      case PM_POST_HIBERNATION:
++              cpu_hotplug_enable_after_thaw();
++              break;
++
++      default:
++              return NOTIFY_DONE;
++      }
++
++      return NOTIFY_OK;
++}
++
++
++int cpu_hotplug_pm_sync_init(void)
++{
++      pm_notifier(cpu_hotplug_pm_callback, 0);
++      return 0;
++}
++core_initcall(cpu_hotplug_pm_sync_init);
++
+ #endif /* CONFIG_PM_SLEEP_SMP */
+ 
+ /**

diff --git a/queue-3.1/series b/queue-3.1/series
index 309006d59dd56b87479c469e5d16bdbc75b6a8cd..dc002c8f3839b90f6567424471b71279375b70fe 100644 (file)
--- a/queue-3.1/series
+++ b/queue-3.1/series
@@ -35,3 +35,4 @@ ohci-final-fix-for-nvidia-problems-i-hope.patch
 igmp-avoid-zero-delay-when-receiving-odd-mixture-of-igmp-queries.patch
 asix-fix-infinite-loop-in-rx_fixup.patch
 bonding-fix-error-handling-if-slave-is-busy-v2.patch
+pm-sleep-fix-race-between-cpu-hotplug-and-freezer.patch