From: Stephen Hemminger <stephen@networkplumber.org>
Date: Thu, 18 May 2017 09:18:12 -0700
Patch-mainline: v4.13-rc1
Subject: scsi: storvsc: remove unnecessary channel inbound lock
Git-commit: 2371cd90abe3fa1b88e15111abf2cc0a26db6e52
References: fate#323887

In storvsc driver, inbound messages do not go through inbound lock.  The
only effect of this lock was is to provide a barrier for connect and
remove logic.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Olaf Hering <ohering@suse.de>
---
 drivers/hv/channel_mgmt.c  | 1 -
 drivers/scsi/storvsc_drv.c | 8 +++-----
 include/linux/hyperv.h     | 1 -
 3 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -332,7 +332,6 @@ static struct vmbus_channel *alloc_channel(void)
 	if (!channel)
 		return NULL;
 
-	spin_lock_init(&channel->inbound_lock);
 	spin_lock_init(&channel->lock);
 
 	INIT_LIST_HEAD(&channel->sc_list);
diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1206,13 +1206,13 @@ static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size,
 static int storvsc_dev_remove(struct hv_device *device)
 {
 	struct storvsc_device *stor_device;
-	unsigned long flags;
 
 	stor_device = hv_get_drvdata(device);
 
-	spin_lock_irqsave(&device->channel->inbound_lock, flags);
 	stor_device->destroy = true;
-	spin_unlock_irqrestore(&device->channel->inbound_lock, flags);
+
+	/* Make sure flag is set before waiting */
+	wmb();
 
 	/*
 	 * At this point, all outbound traffic should be disable. We
@@ -1229,9 +1229,7 @@ static int storvsc_dev_remove(struct hv_device *device)
 	 * we have drained - to drain the outgoing packets, we need to
 	 * allow incoming packets.
 	 */
-	spin_lock_irqsave(&device->channel->inbound_lock, flags);
 	hv_set_drvdata(device, NULL);
-	spin_unlock_irqrestore(&device->channel->inbound_lock, flags);
 
 	/* Close the channel */
 	vmbus_close(device->channel);
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -744,7 +744,6 @@ struct vmbus_channel {
 	u32 ringbuffer_pagecount;
 	struct hv_ring_buffer_info outbound;	/* send to parent */
 	struct hv_ring_buffer_info inbound;	/* receive from parent */
-	spinlock_t inbound_lock;
 
 	struct vmbus_close_msg close_msg;