[PATCH 2/2] storvsc: remove unnecessary channel inbound lock

[Stephen Hemminger]

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 <sthem...@microsoft.com>
---
 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
index 735f9363f2e4..685572bae1f0 100644
--- 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
index f8a1649e4c63..8d955db6424f 100644
--- 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
index e09fc8290c2f..b7d7bbec74e0 100644
--- 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;
 
-- 
2.11.0