Commit e513229b4c38 ("Drivers: hv: vmbus: prevent cpu offlining on newer
hypervisors") was altering smp_ops.cpu_disable to prevent CPU offlining.
We can bo better by using cpu_hotplug_enable/disable functions instead of
such hard-coding.

Reported-by: Radim Krčmář <rkrc...@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuzn...@redhat.com>
Signed-off-by: K. Y. Srinivasan <k...@microsoft.com>
---
 drivers/hv/vmbus_drv.c | 38 ++++----------------------------------
 1 file changed, 4 insertions(+), 34 deletions(-)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index cf20400..6de65fb 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -763,38 +763,6 @@ static void vmbus_isr(void)
        }
 }
 
-#ifdef CONFIG_HOTPLUG_CPU
-static int hyperv_cpu_disable(void)
-{
-       return -ENOSYS;
-}
-
-static void hv_cpu_hotplug_quirk(bool vmbus_loaded)
-{
-       static void *previous_cpu_disable;
-
-       /*
-        * Offlining a CPU when running on newer hypervisors (WS2012R2, Win8,
-        * ...) is not supported at this moment as channel interrupts are
-        * distributed across all of them.
-        */
-
-       if ((vmbus_proto_version == VERSION_WS2008) ||
-           (vmbus_proto_version == VERSION_WIN7))
-               return;
-
-       if (vmbus_loaded) {
-               previous_cpu_disable = smp_ops.cpu_disable;
-               smp_ops.cpu_disable = hyperv_cpu_disable;
-               pr_notice("CPU offlining is not supported by hypervisor\n");
-       } else if (previous_cpu_disable)
-               smp_ops.cpu_disable = previous_cpu_disable;
-}
-#else
-static void hv_cpu_hotplug_quirk(bool vmbus_loaded)
-{
-}
-#endif
 
 /*
  * vmbus_bus_init -Main vmbus driver initialization routine.
@@ -836,7 +804,8 @@ static int vmbus_bus_init(int irq)
        if (ret)
                goto err_alloc;
 
-       hv_cpu_hotplug_quirk(true);
+       if (vmbus_proto_version > VERSION_WIN7)
+               cpu_hotplug_disable();
 
        /*
         * Only register if the crash MSRs are available
@@ -1121,7 +1090,8 @@ static void __exit vmbus_exit(void)
                smp_call_function_single(cpu, hv_synic_cleanup, NULL, 1);
        }
        acpi_bus_unregister_driver(&vmbus_acpi_driver);
-       hv_cpu_hotplug_quirk(false);
+       if (vmbus_proto_version > VERSION_WIN7)
+               cpu_hotplug_enable();
 }
 
 
-- 
2.4.2

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