Drivers: hv: Manage event tasklets on per-cpu basis

Now that we can potentially take vmbus interrupts on any CPU, make the
tasklets per-CPU.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 19 insertions, 3 deletions

diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index e989c6fd1f8f..363532add4c7 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -27,6 +27,7 @@
 #include <linux/vmalloc.h>
 #include <linux/hyperv.h>
 #include <linux/version.h>
+#include <linux/interrupt.h>
 #include <asm/hyperv.h>
 #include "hyperv_vmbus.h"
 
@@ -137,6 +138,8 @@ int hv_init(void)
                sizeof(void *) * NR_CPUS);
         memset(hv_context.vp_index, 0,
                sizeof(int) * NR_CPUS);
+        memset(hv_context.event_dpc, 0,
+               sizeof(void *) * NR_CPUS);
 
         max_leaf = query_hypervisor_info();
 
@@ -285,6 +288,15 @@ void hv_synic_init(void *irqarg)
         /* Check the version */
         rdmsrl(HV_X64_MSR_SVERSION, version);
 
+        hv_context.event_dpc[cpu] = (struct tasklet_struct *)
+                                        kmalloc(sizeof(struct tasklet_struct),
+                                                GFP_ATOMIC);
+        if (hv_context.event_dpc[cpu] == NULL) {
+                pr_err("Unable to allocate event dpc\n");
+                goto cleanup;
+        }
+        tasklet_init(hv_context.event_dpc[cpu], vmbus_on_event, cpu);
+
         hv_context.synic_message_page[cpu] =
                 (void *)get_zeroed_page(GFP_ATOMIC);
 
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 9135a6fcf3bd..becb106918d6 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -504,6 +504,12 @@ struct hv_context {
          * Linux cpuid 'a'.
          */
         u32 vp_index[NR_CPUS];
+        /*
+         * Starting with win8, we can take channel interrupts on any CPU;
+         * we will manage the tasklet that handles events on a per CPU
+         * basis.
+         */
+        struct tasklet_struct *event_dpc[NR_CPUS];
 };
 
 extern struct hv_context hv_context;
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 4c92337ddae6..6e4f85720f26 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -41,7 +41,6 @@
 static struct acpi_device  *hv_acpi_dev;
 
 static struct tasklet_struct msg_dpc;
-static struct tasklet_struct event_dpc;
 static struct completion probe_event;
 static int irq;
 
@@ -483,7 +482,7 @@ static irqreturn_t vmbus_isr(int irq, void *dev_id)
         }
 
         if (handled)
-                tasklet_schedule(&event_dpc);
+                tasklet_schedule(hv_context.event_dpc[cpu]);
 
 
         page_addr = hv_context.synic_message_page[cpu];
@@ -523,7 +522,6 @@ static int vmbus_bus_init(int irq)
         }
 
         tasklet_init(&msg_dpc, vmbus_on_msg_dpc, 0);
-        tasklet_init(&event_dpc, vmbus_on_event, 0);
 
         ret = bus_register(&hv_bus);
         if (ret)