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

[ Upstream commit 4d3c5c69191f98c7f7e699ff08d2fd96d7070ddb ]

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>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index fe00b12e44178a4b9f3f4f5bfd7b447457c417d5..ce0ba20627236dde727d2f6fd486a1b8d281d327 100644 (file)
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -711,7 +711,6 @@ 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 edd34c167a9bd44e70c34e24e506798562dc28a4..d01689079e9b9a2e64bc733b3e70cfb9a7f7068d 100644 (file)
--- 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);
        }
 
@@ -1302,49 +1301,6 @@ 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;

diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index ed74888087f1327d9fd8cef5b22698a9d0203533..dcb6977afce931d2c3407f38c0ed2565b778bdc1 100644 (file)
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -830,15 +830,6 @@ struct vmbus_channel {
         * All Sub-channels of a primary channel are linked here.
         */
        struct list_head sc_list;
-       /*
-        * Current number of sub-channels.
-        */
-       int num_sc;
-       /*
-        * Number of a sub-channel (position within sc_list) which is supposed
-        * to be used as the next outgoing channel.
-        */
-       int next_oc;
        /*
         * The primary channel this sub-channel belongs to.
         * This will be NULL for the primary channel.
@@ -972,14 +963,6 @@ void vmbus_set_sc_create_callback(struct vmbus_channel *primary_channel,
 void vmbus_set_chn_rescind_callback(struct vmbus_channel *channel,
                void (*chn_rescind_cb)(struct vmbus_channel *));
 
-/*
- * Retrieve the (sub) channel on which to send an outgoing request.
- * When a primary channel has multiple sub-channels, we choose a
- * channel whose VCPU binding is closest to the VCPU on which
- * this call is being made.
- */
-struct vmbus_channel *vmbus_get_outgoing_channel(struct vmbus_channel *primary);
-
 /*
  * Check if sub-channels have already been offerred. This API will be useful
  * when the driver is unloaded after establishing sub-channels. In this case,