Merge tag 'char-misc-4.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

Pull char / misc driver updates from Greg KH:
 "Here's the big char and misc driver update for 4.7-rc1.

  Lots of different tiny driver subsystems have updates here with new
  drivers and functionality.  Details in the shortlog.

  All have been in linux-next with no reported issues for a while"

* tag 'char-misc-4.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (125 commits)
  mcb: Delete num_cells variable which is not required
  mcb: Fixed bar number assignment for the gdd
  mcb: Replace ioremap and request_region with the devm version
  mcb: Implement bus->dev.release callback
  mcb: export bus information via sysfs
  mcb: Correctly initialize the bus's device
  mei: bus: call mei_cl_read_start under device lock
  coresight: etb10: adjust read pointer only when needed
  coresight: configuring ETF in FIFO mode when acting as link
  coresight: tmc: implementing TMC-ETF AUX space API
  coresight: moving struct cs_buffers to header file
  coresight: tmc: keep track of memory width
  coresight: tmc: make sysFS and Perf mode mutually exclusive
  coresight: tmc: dump system memory content only when needed
  coresight: tmc: adding mode of operation for link/sinks
  coresight: tmc: getting rid of multiple read access
  coresight: tmc: allocating memory when needed
  coresight: tmc: making prepare/unprepare functions generic
  coresight: tmc: splitting driver in ETB/ETF and ETR components
  coresight: tmc: cleaning up header file
  ...

1 files changed, 19 insertions, 4 deletions

diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 12321b93a756..718b5c72f0c8 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -36,6 +36,11 @@
 #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);