Drivers: hv: vmbus: Properly protect calls to smp_processor_id()

Disable preemption when sampling current processor ID when preemption
is otherwise possible.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Tested-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 20 insertions, 8 deletions

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 19bad59073e6..433f72a1c006 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -486,11 +486,14 @@ static int vmbus_close_internal(struct vmbus_channel *channel)
         channel->state = CHANNEL_OPEN_STATE;
         channel->sc_creation_callback = NULL;
         /* Stop callback and cancel the timer asap */
-        if (channel->target_cpu != smp_processor_id())
+        if (channel->target_cpu != get_cpu()) {
+                put_cpu();
                 smp_call_function_single(channel->target_cpu, reset_channel_cb,
                                          channel, true);
-        else
+        } else {
                 reset_channel_cb(channel);
+                put_cpu();
+        }
 
         /* Send a closing message */
 
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index ed9350d42764..a2d1a9612c86 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -224,11 +224,14 @@ static void vmbus_process_rescind_offer(struct work_struct *work)
         msg.header.msgtype = CHANNELMSG_RELID_RELEASED;
         vmbus_post_msg(&msg, sizeof(struct vmbus_channel_relid_released));
 
-        if (channel->target_cpu != smp_processor_id())
+        if (channel->target_cpu != get_cpu()) {
+                put_cpu();
                 smp_call_function_single(channel->target_cpu,
                                          percpu_channel_deq, channel, true);
-        else
+        } else {
                 percpu_channel_deq(channel);
+                put_cpu();
+        }
 
         if (channel->primary_channel == NULL) {
                 spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
@@ -294,12 +297,15 @@ static void vmbus_process_offer(struct work_struct *work)
         spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
 
         if (enq) {
-                if (newchannel->target_cpu != smp_processor_id())
+                if (newchannel->target_cpu != get_cpu()) {
+                        put_cpu();
                         smp_call_function_single(newchannel->target_cpu,
                                                  percpu_channel_enq,
                                                  newchannel, true);
-                else
+                } else {
                         percpu_channel_enq(newchannel);
+                        put_cpu();
+                }
         }
         if (!fnew) {
                 /*
@@ -314,12 +320,15 @@ static void vmbus_process_offer(struct work_struct *work)
                         list_add_tail(&newchannel->sc_list, &channel->sc_list);
                         spin_unlock_irqrestore(&channel->sc_lock, flags);
 
-                        if (newchannel->target_cpu != smp_processor_id())
+                        if (newchannel->target_cpu != get_cpu()) {
+                                put_cpu();
                                 smp_call_function_single(newchannel->target_cpu,
                                                          percpu_channel_enq,
                                                          newchannel, true);
-                        else
+                        } else {
                                 percpu_channel_enq(newchannel);
+                                put_cpu();
+                        }
 
                         newchannel->state = CHANNEL_OPEN_STATE;
                         if (channel->sc_creation_callback != NULL)