Merge tag 'sunxi-drm-fixes-for-4.7' of https://git.kernel.org/pub/scm/linux/kernel...

[deliverable/linux.git] / drivers / hv / hyperv_vmbus.h

diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 12321b93a756b947f09b95f79dade93849794040..718b5c72f0c8bd86a8a1a6caba5b556e60c1b6f8 100644 (file)
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -35,6 +35,11 @@
  */
 #define HV_UTIL_TIMEOUT 30
 
+/*
+ * Timeout for guest-host handshake for services.
+ */
+#define HV_UTIL_NEGO_TIMEOUT 60
+
 /*
  * The below CPUID leaves are present if VersionAndFeatures.HypervisorPresent
  * is set by CPUID(HVCPUID_VERSION_FEATURES).
@@ -620,9 +625,21 @@ extern struct vmbus_channel_message_table_entry
        channel_message_table[CHANNELMSG_COUNT];
 
 /* Free the message slot and signal end-of-message if required */
-static inline void vmbus_signal_eom(struct hv_message *msg)
+static inline void vmbus_signal_eom(struct hv_message *msg, u32 old_msg_type)
 {
-       msg->header.message_type = HVMSG_NONE;
+       /*
+        * On crash we're reading some other CPU's message page and we need
+        * to be careful: this other CPU may already had cleared the header
+        * and the host may already had delivered some other message there.
+        * In case we blindly write msg->header.message_type we're going
+        * to lose it. We can still lose a message of the same type but
+        * we count on the fact that there can only be one
+        * CHANNELMSG_UNLOAD_RESPONSE and we don't care about other messages
+        * on crash.
+        */
+       if (cmpxchg(&msg->header.message_type, old_msg_type,
+                   HVMSG_NONE) != old_msg_type)
+               return;
 
        /*
         * Make sure the write to MessageType (ie set to
@@ -667,8 +684,6 @@ void vmbus_disconnect(void);
 
 int vmbus_post_msg(void *buffer, size_t buflen);
 
-void vmbus_set_event(struct vmbus_channel *channel);
-
 void vmbus_on_event(unsigned long data);
 void vmbus_on_msg_dpc(unsigned long data);