4 files changed, 37 insertions, 26 deletions

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 2f6270d76b79..b2bb5aafaa2f 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -820,13 +820,6 @@ static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
 	}
 
 	/*
-	 * By default we setup state to enable batched
-	 * reading. A specific service can choose to
-	 * disable this prior to opening the channel.
-	 */
-	newchannel->batched_reading = true;
-
-	/*
 	 * Setup state for signalling the host.
 	 */
 	newchannel->sig_event = (struct hv_input_signal_event *)
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 27e72dc07e12..a8366fec1458 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -300,9 +300,7 @@ struct vmbus_channel *relid2channel(u32 relid)
 void vmbus_on_event(unsigned long data)
 {
 	struct vmbus_channel *channel = (void *) data;
-	void *arg;
-	bool read_state;
-	u32 bytes_to_read;
+	void (*callback_fn)(void *);
 
 	/*
 	 * A channel once created is persistent even when there
@@ -312,9 +310,13 @@ void vmbus_on_event(unsigned long data)
 	 * Thus, checking and invoking the driver specific callback takes
 	 * care of orderly unloading of the driver.
 	 */
-	if (channel->onchannel_callback != NULL) {
-		arg = channel->channel_callback_context;
-		read_state = channel->batched_reading;
+	callback_fn = READ_ONCE(channel->onchannel_callback);
+	if (unlikely(callback_fn == NULL))
+		return;
+
+	(*callback_fn)(channel->channel_callback_context);
+
+	if (channel->callback_mode == HV_CALL_BATCHED) {
 		/*
 		 * This callback reads the messages sent by the host.
 		 * We can optimize host to guest signaling by ensuring:
@@ -326,16 +328,11 @@ void vmbus_on_event(unsigned long data)
 		 *    state is set we check to see if additional packets are
 		 *    available to read. In this case we repeat the process.
 		 */
+		if (hv_end_read(&channel->inbound) != 0) {
+			hv_begin_read(&channel->inbound);
 
-		do {
-			if (read_state)
-				hv_begin_read(&channel->inbound);
-			channel->onchannel_callback(arg);
-			if (read_state)
-				bytes_to_read = hv_end_read(&channel->inbound);
-			else
-				bytes_to_read = 0;
-		} while (read_state && (bytes_to_read != 0));
+			tasklet_schedule(&channel->callback_event);
+		}
 	}
 }
 
diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
index 098cd3dc7db2..3042eaa13062 100644
--- a/drivers/hv/hv_util.c
+++ b/drivers/hv/hv_util.c
@@ -435,8 +435,7 @@ static int util_probe(struct hv_device *dev,
 	 * Turn off batched reading for all util drivers before we open the
 	 * channel.
 	 */
-
-	set_channel_read_state(dev->channel, false);
+	set_channel_read_mode(dev->channel, HV_CALL_DIRECT);
 
 	hv_set_drvdata(dev, srv);
 
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index eaf1a10b0245..f7f6b9144b07 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -887,6 +887,18 @@ msg_handled:
 
 
 /*
+ * Direct callback for channels using other deferred processing
+ */
+static void vmbus_channel_isr(struct vmbus_channel *channel)
+{
+	void (*callback_fn)(void *);
+
+	callback_fn = READ_ONCE(channel->onchannel_callback);
+	if (likely(callback_fn != NULL))
+		(*callback_fn)(channel->channel_callback_context);
+}
+
+/*
  * Schedule all channels with events pending
  */
 static void vmbus_chan_sched(struct hv_per_cpu_context *hv_cpu)
@@ -927,9 +939,19 @@ static void vmbus_chan_sched(struct hv_per_cpu_context *hv_cpu)
 
 		/* Find channel based on relid */
 		list_for_each_entry(channel, &hv_cpu->chan_list, percpu_list) {
-			if (channel->offermsg.child_relid == relid) {
-				tasklet_schedule(&channel->callback_event);
+			if (channel->offermsg.child_relid != relid)
+				continue;
+
+			switch (channel->callback_mode) {
+			case HV_CALL_ISR:
+				vmbus_channel_isr(channel);
 				break;
+
+			case HV_CALL_BATCHED:
+				hv_begin_read(&channel->inbound);
+				/* fallthrough */
+			case HV_CALL_DIRECT:
+				tasklet_schedule(&channel->callback_event);
 			}
 		}
 	}