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[PATCH] xen: Add comment for missing FROZEN notifier transitions

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Xen guests do not offline/online CPUs during suspend/resume and
therefore FROZEN notifier transitions are not required. Add this
explanation as a comment in the code to get not confused why
CPU_TASKS_FROZEN masked transitions are not considered.

Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: xen-devel@lists.xenproject.org 
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 arch/arm/xen/enlighten.c         |    6 ++++++
 arch/x86/xen/enlighten.c         |    7 +++++++
 drivers/xen/events/events_fifo.c |    6 ++++++
 3 files changed, 19 insertions(+)

--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -213,6 +213,12 @@ static int xen_cpu_notification(struct n
 				unsigned long action,
 				void *hcpu)
 {
+	/*
+	 * Xen guests do not offline/online CPUs during
+	 * suspend/resume, thus CPU_TASKS_FROZEN masked transitions
+	 * are not considered.
+	 */
+
 	switch (action) {
 	case CPU_STARTING:
 		xen_percpu_init();
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1788,6 +1788,13 @@ static int xen_hvm_cpu_notify(struct not
 			      void *hcpu)
 {
 	int cpu = (long)hcpu;
+
+	/*
+	 * Xen guests do not offline/online CPUs during
+	 * suspend/resume, thus CPU_TASKS_FROZEN masked transitions
+	 * are not considered.
+	 */
+
 	switch (action) {
 	case CPU_UP_PREPARE:
 		xen_vcpu_setup(cpu);
--- a/drivers/xen/events/events_fifo.c
+++ b/drivers/xen/events/events_fifo.c
@@ -425,6 +425,12 @@ static int evtchn_fifo_cpu_notification(
 	int cpu = (long)hcpu;
 	int ret = 0;
 
+	/*
+	 * Xen guests do not offline/online CPUs during
+	 * suspend/resume, thus CPU_TASKS_FROZEN masked transitions
+	 * are not considered.
+	*/
+
 	switch (action) {
 	case CPU_UP_PREPARE:
 		if (!per_cpu(cpu_control_block, cpu))

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[PATCH] xen: Add comment for missing FROZEN notifier transitions Anna-Maria Gleixner <anna-maria@linutronix.de> - 2016-04-04 14:40 +0200
  Re: [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier  transitions Julien Grall <julien.grall@arm.com> - 2016-04-04 18:30 +0200
    Re: [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier  transitions David Vrabel <david.vrabel@citrix.com> - 2016-04-04 18:40 +0200
      Re: [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier  transitions Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-04-04 18:50 +0200
        Re: [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier  transitions Juergen Gross <jgross@suse.com> - 2016-04-05 06:30 +0200
          Re: [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier  transitions Stefano Stabellini <sstabellini@kernel.org> - 2016-04-07 02:00 +0200
  Re: [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier  transitions David Vrabel <dvrabel@cantab.net> - 2016-04-06 15:20 +0200
    Re: [PREEMPT-RT] [Xen-devel] [PATCH] xen: Add comment for missing  FROZEN notifier transitions Anna-Maria Gleixner <anna-maria@linutronix.de> - 2016-04-06 16:10 +0200
    Re: [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier  transitions Stefano Stabellini <sstabellini@kernel.org> - 2016-04-07 02:00 +0200

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