Drivers: hv: vmbus: add a sysfs attr to show the binding of channel/VP

This is useful to analyze performance issue.

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>

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 8c3eaee8c54c7f32f780decd627bc5ae34ad89e6..45d6d7a0ed89c3caeead3704a7e469c41f07cc49 100644 (file)
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -441,6 +441,43 @@ static ssize_t in_write_bytes_avail_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(in_write_bytes_avail);
 
+static ssize_t channel_vp_mapping_show(struct device *dev,
+                                      struct device_attribute *dev_attr,
+                                      char *buf)
+{
+       struct hv_device *hv_dev = device_to_hv_device(dev);
+       struct vmbus_channel *channel = hv_dev->channel, *cur_sc;
+       unsigned long flags;
+       int buf_size = PAGE_SIZE, n_written, tot_written;
+       struct list_head *cur;
+
+       if (!channel)
+               return -ENODEV;
+
+       tot_written = snprintf(buf, buf_size, "%u:%u\n",
+               channel->offermsg.child_relid, channel->target_cpu);
+
+       spin_lock_irqsave(&channel->lock, flags);
+
+       list_for_each(cur, &channel->sc_list) {
+               if (tot_written >= buf_size - 1)
+                       break;
+
+               cur_sc = list_entry(cur, struct vmbus_channel, sc_list);
+               n_written = scnprintf(buf + tot_written,
+                                    buf_size - tot_written,
+                                    "%u:%u\n",
+                                    cur_sc->offermsg.child_relid,
+                                    cur_sc->target_cpu);
+               tot_written += n_written;
+       }
+
+       spin_unlock_irqrestore(&channel->lock, flags);
+
+       return tot_written;
+}
+static DEVICE_ATTR_RO(channel_vp_mapping);
+
 /* Set up per device attributes in /sys/bus/vmbus/devices/<bus device> */
 static struct attribute *vmbus_attrs[] = {
        &dev_attr_id.attr,
@@ -465,6 +502,7 @@ static struct attribute *vmbus_attrs[] = {
        &dev_attr_in_write_index.attr,
        &dev_attr_in_read_bytes_avail.attr,
        &dev_attr_in_write_bytes_avail.attr,
+       &dev_attr_channel_vp_mapping.attr,
        NULL,
 };
 ATTRIBUTE_GROUPS(vmbus);