Drivers: hv: vmbus: Remove the useless API vmbus_get_outgoing_channel()

Commit d86adf482b84 ("scsi: storvsc: Enable multi-queue support") removed
the usage of the API in Jan 2017, and the API is not used since then.

netvsc and storvsc have their own algorithms to determine the outgoing
channel, so this API is useless.

And the API is potentially unsafe, because it reads primary->num_sc without
any lock held. This can be risky considering the RESCIND-OFFER message.

Let's remove the API.

Cc: Long Li <longli@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 0 insertions, 46 deletions

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index de8193f3b838..f96a77b18bb9 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -703,7 +703,6 @@ int vmbus_disconnect_ring(struct vmbus_channel *channel)
 	/* Snapshot the list of subchannels */
 	spin_lock_irqsave(&channel->lock, flags);
 	list_splice_init(&channel->sc_list, &list);
-	channel->num_sc = 0;
 	spin_unlock_irqrestore(&channel->lock, flags);
 
 	list_for_each_entry_safe(cur_channel, tmp, &list, sc_list) {
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 6277597d3d58..82e673671087 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -405,7 +405,6 @@ void hv_process_channel_removal(struct vmbus_channel *channel)
 		primary_channel = channel->primary_channel;
 		spin_lock_irqsave(&primary_channel->lock, flags);
 		list_del(&channel->sc_list);
-		primary_channel->num_sc--;
 		spin_unlock_irqrestore(&primary_channel->lock, flags);
 	}
 
@@ -483,7 +482,6 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
 			newchannel->primary_channel = channel;
 			spin_lock_irqsave(&channel->lock, flags);
 			list_add_tail(&newchannel->sc_list, &channel->sc_list);
-			channel->num_sc++;
 			spin_unlock_irqrestore(&channel->lock, flags);
 		} else {
 			goto err_free_chan;
@@ -1239,49 +1237,6 @@ cleanup:
 	return ret;
 }
 
-/*
- * Retrieve the (sub) channel on which to send an outgoing request.
- * When a primary channel has multiple sub-channels, we try to
- * distribute the load equally amongst all available channels.
- */
-struct vmbus_channel *vmbus_get_outgoing_channel(struct vmbus_channel *primary)
-{
-	struct list_head *cur, *tmp;
-	int cur_cpu;
-	struct vmbus_channel *cur_channel;
-	struct vmbus_channel *outgoing_channel = primary;
-	int next_channel;
-	int i = 1;
-
-	if (list_empty(&primary->sc_list))
-		return outgoing_channel;
-
-	next_channel = primary->next_oc++;
-
-	if (next_channel > (primary->num_sc)) {
-		primary->next_oc = 0;
-		return outgoing_channel;
-	}
-
-	cur_cpu = hv_cpu_number_to_vp_number(smp_processor_id());
-	list_for_each_safe(cur, tmp, &primary->sc_list) {
-		cur_channel = list_entry(cur, struct vmbus_channel, sc_list);
-		if (cur_channel->state != CHANNEL_OPENED_STATE)
-			continue;
-
-		if (cur_channel->target_vp == cur_cpu)
-			return cur_channel;
-
-		if (i == next_channel)
-			return cur_channel;
-
-		i++;
-	}
-
-	return outgoing_channel;
-}
-EXPORT_SYMBOL_GPL(vmbus_get_outgoing_channel);
-
 static void invoke_sc_cb(struct vmbus_channel *primary_channel)
 {
 	struct list_head *cur, *tmp;