@@ -315,6 +315,8 @@ static struct vmbus_channel *alloc_channel(void)
if (!channel)
return NULL;
+ channel->dev_num = HV_DEV_NUM_INVALID;
+
spin_lock_init(&channel->lock);
init_completion(&channel->rescind_event);
@@ -541,6 +543,44 @@ static void vmbus_add_channel_work(struct work_struct *work)
}
/*
+ * Get the first available device number of its type, then
+ * record it in the channel structure.
+ */
+static void hv_set_devnum(struct vmbus_channel *newchannel)
+{
+ struct vmbus_channel *channel;
+ int i = -1;
+ bool in_use;
+
+ BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
+
+ /*
+ * Iterate through each possible device number starting at zero.
+ * If the device number is already in use for a device of this type,
+ * try the next device number until finding one that is not in use.
+ * This approach selects the smallest device number that is not in
+ * use, and so reuses any numbers that are freed by devices that
+ * have been removed.
+ */
+ do {
+ i++;
+ in_use = false;
+
+ list_for_each_entry(channel, &vmbus_connection.chn_list,
+ listentry) {
+ if (i == channel->dev_num &&
+ guid_equal(&channel->offermsg.offer.if_type,
+ &newchannel->offermsg.offer.if_type)) {
+ in_use = true;
+ break;
+ }
+ }
+ } while (in_use);
+
+ newchannel->dev_num = i;
+}
+
+/*
* vmbus_process_offer - Process the offer by creating a channel/device
* associated with this offer
*/
@@ -573,10 +613,12 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
}
}
- if (fnew)
+ if (fnew) {
+ hv_set_devnum(newchannel);
+
list_add_tail(&newchannel->listentry,
&vmbus_connection.chn_list);
- else {
+ } else {
/*
* Check to see if this is a valid sub-channel.
*/
@@ -718,6 +718,8 @@ struct vmbus_device {
bool perf_device;
};
+#define HV_DEV_NUM_INVALID (-1)
+
struct vmbus_channel {
struct list_head listentry;
@@ -849,6 +851,10 @@ struct vmbus_channel {
*/
struct vmbus_channel *primary_channel;
/*
+ * Used for device naming based on channel offer sequence.
+ */
+ int dev_num;
+ /*
* Support per-channel state for use by vmbus drivers.
*/
void *per_channel_state;
This number is set to the first available number, starting from zero, when a VMBus device’s primary channel is offered. It will be used for stable naming when Async probing is used. Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com> --- Changes V3: Rename a local var, add code comments. V2: Use nest loops in hv_set_devnum, instead of goto. --- drivers/hv/channel_mgmt.c | 46 ++++++++++++++++++++++++++++++++++++++++++++-- include/linux/hyperv.h | 6 ++++++ 2 files changed, 50 insertions(+), 2 deletions(-)