Drivers: hv: Turn off batched reading for util drivers

Util driver is not a performance critical driver and furthermore some
util services such as KVP can only handle one outstanding message
from the host. Turn off batched reading for util drivers.

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>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
index a0667de7a04c..a62a76062508 100644
--- a/drivers/hv/hv_util.c
+++ b/drivers/hv/hv_util.c
@@ -274,6 +274,16 @@ static int util_probe(struct hv_device *dev,
                 }
         }
 
+        /*
+         * The set of services managed by the util driver are not performance
+         * critical and do not need batched reading. Furthermore, some services
+         * such as KVP can only handle one message from the host at a time.
+         * Turn off batched reading for all util drivers before we open the
+         * channel.
+         */
+
+        set_channel_read_state(dev->channel, false);
+
         ret = vmbus_open(dev->channel, 4 * PAGE_SIZE, 4 * PAGE_SIZE, NULL, 0,
                         srv->util_cb, dev->channel);
         if (ret)