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

[Anna-Maria Gleixner <anna-maria@xxxxxxxxxxxxx>]

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@xxxxxxxxxx>
Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx 
Signed-off-by: Anna-Maria Gleixner <anna-maria@xxxxxxxxxxxxx>
---
 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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