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Subject[PATCH 3.18 047/124] xen/acpi: upload PM state from init-domain to Xen
Date
3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ankur Arora <ankur.a.arora@oracle.com>

commit 1914f0cd203c941bba72f9452c8290324f1ef3dc upstream.

This was broken in commit cd979883b9ed ("xen/acpi-processor:
fix enabling interrupts on syscore_resume"). do_suspend (from
xen/manage.c) and thus xen_resume_notifier never get called on
the initial-domain at resume (it is if running as guest.)

The rationale for the breaking change was that upload_pm_data()
potentially does blocking work in syscore_resume(). This patch
addresses the original issue by scheduling upload_pm_data() to
execute in workqueue context.

Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Based-on-patch-by: Konrad Wilk <konrad.wilk@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/xen/xen-acpi-processor.c | 34 ++++++++++++++++++++++++++--------
1 file changed, 26 insertions(+), 8 deletions(-)

--- a/drivers/xen/xen-acpi-processor.c
+++ b/drivers/xen/xen-acpi-processor.c
@@ -27,10 +27,10 @@
#include <linux/init.h>
#include <linux/module.h>
#include <linux/types.h>
+#include <linux/syscore_ops.h>
#include <linux/acpi.h>
#include <acpi/processor.h>
#include <xen/xen.h>
-#include <xen/xen-ops.h>
#include <xen/interface/platform.h>
#include <asm/xen/hypercall.h>

@@ -466,15 +466,33 @@ static int xen_upload_processor_pm_data(
return rc;
}

-static int xen_acpi_processor_resume(struct notifier_block *nb,
- unsigned long action, void *data)
+static void xen_acpi_processor_resume_worker(struct work_struct *dummy)
{
+ int rc;
+
bitmap_zero(acpi_ids_done, nr_acpi_bits);
- return xen_upload_processor_pm_data();
+
+ rc = xen_upload_processor_pm_data();
+ if (rc != 0)
+ pr_info("ACPI data upload failed, error = %d\n", rc);
+}
+
+static void xen_acpi_processor_resume(void)
+{
+ static DECLARE_WORK(wq, xen_acpi_processor_resume_worker);
+
+ /*
+ * xen_upload_processor_pm_data() calls non-atomic code.
+ * However, the context for xen_acpi_processor_resume is syscore
+ * with only the boot CPU online and in an atomic context.
+ *
+ * So defer the upload for some point safer.
+ */
+ schedule_work(&wq);
}

-struct notifier_block xen_acpi_processor_resume_nb = {
- .notifier_call = xen_acpi_processor_resume,
+static struct syscore_ops xap_syscore_ops = {
+ .resume = xen_acpi_processor_resume,
};

static int __init xen_acpi_processor_init(void)
@@ -527,7 +545,7 @@ static int __init xen_acpi_processor_ini
if (rc)
goto err_unregister;

- xen_resume_notifier_register(&xen_acpi_processor_resume_nb);
+ register_syscore_ops(&xap_syscore_ops);

return 0;
err_unregister:
@@ -546,7 +564,7 @@ static void __exit xen_acpi_processor_ex
{
int i;

- xen_resume_notifier_unregister(&xen_acpi_processor_resume_nb);
+ unregister_syscore_ops(&xap_syscore_ops);
kfree(acpi_ids_done);
kfree(acpi_id_present);
kfree(acpi_id_cst_present);

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