net: new counter for tx_timeout errors in sysfs

This adds the /sys/class/net/DEV/queues/Q/tx_timeout attribute
containing the total number of timeout events on the given queue. It
is always available with CONFIG_SYSFS, independently of
CONFIG_RPS/XPS.

Credits to Stephen Hemminger for a preliminary version of this patch.

Tested:
  without CONFIG_SYSFS (compilation only)
  with sysfs and without CONFIG_RPS & CONFIG_XPS
  with sysfs and without CONFIG_RPS
  with sysfs and without CONFIG_XPS
  with defaults

Signed-off-by: David Decotigny <david.decotigny@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Conflicts:

	include/linux/netdevice.h

Signed-off-by: Christopher Kenna <cjk@cs.unc.edu>

3 files changed, 42 insertions, 8 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index c6d6d486d31..a672989daa2 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -556,7 +556,7 @@ struct netdev_queue {
         struct Qdisc            *qdisc;
         unsigned long           state;
         struct Qdisc            *qdisc_sleeping;
-#ifdef CONFIG_RPS
+#ifdef CONFIG_SYSFS
         struct kobject          kobj;
 #endif
 #if defined(CONFIG_XPS) && defined(CONFIG_NUMA)
@@ -571,6 +571,12 @@ struct netdev_queue {
          * please use this field instead of dev->trans_start
          */
         unsigned long           trans_start;
+
+        /*
+         * Number of TX timeouts for this queue
+         * (/sys/class/net/DEV/Q/trans_timeout)
+         */
+        unsigned long           trans_timeout;
 } ____cacheline_aligned_in_smp;
 
 static inline int netdev_queue_numa_node_read(const struct netdev_queue *q)
@@ -1214,9 +1220,11 @@ struct net_device {
 
         unsigned char           broadcast[MAX_ADDR_LEN];        /* hw bcast add */
 
-#ifdef CONFIG_RPS
+#ifdef CONFIG_SYSFS
         struct kset             *queues_kset;
+#endif
 
+#ifdef CONFIG_RPS
         struct netdev_rx_queue  *_rx;
 
         /* Number of RX queues allocated at register_netdev() time */
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 33d2a1fba13..ec4eae35330 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -781,7 +781,7 @@ net_rx_queue_update_kobjects(struct net_device *net, int old_num, int new_num)
 #endif
 }
 
-#ifdef CONFIG_XPS
+#ifdef CONFIG_SYSFS
 /*
  * netdev_queue sysfs structures and functions.
  */
@@ -827,6 +827,23 @@ static const struct sysfs_ops netdev_queue_sysfs_ops = {
         .store = netdev_queue_attr_store,
 };
 
+static ssize_t show_trans_timeout(struct netdev_queue *queue,
+                                  struct netdev_queue_attribute *attribute,
+                                  char *buf)
+{
+        unsigned long trans_timeout;
+
+        spin_lock_irq(&queue->_xmit_lock);
+        trans_timeout = queue->trans_timeout;
+        spin_unlock_irq(&queue->_xmit_lock);
+
+        return sprintf(buf, "%lu", trans_timeout);
+}
+
+static struct netdev_queue_attribute queue_trans_timeout =
+        __ATTR(tx_timeout, S_IRUGO, show_trans_timeout, NULL);
+
+#ifdef CONFIG_XPS
 static inline unsigned int get_netdev_queue_index(struct netdev_queue *queue)
 {
         struct net_device *dev = queue->dev;
@@ -1021,12 +1038,17 @@ error:
 
 static struct netdev_queue_attribute xps_cpus_attribute =
     __ATTR(xps_cpus, S_IRUGO | S_IWUSR, show_xps_map, store_xps_map);
+#endif /* CONFIG_XPS */
 
 static struct attribute *netdev_queue_default_attrs[] = {
+        &queue_trans_timeout.attr,
+#ifdef CONFIG_XPS
         &xps_cpus_attribute.attr,
+#endif
         NULL
 };
 
+#ifdef CONFIG_XPS
 static void netdev_queue_release(struct kobject *kobj)
 {
         struct netdev_queue *queue = to_netdev_queue(kobj);
@@ -1077,10 +1099,13 @@ static void netdev_queue_release(struct kobject *kobj)
         memset(kobj, 0, sizeof(*kobj));
         dev_put(queue->dev);
 }
+#endif /* CONFIG_XPS */
 
 static struct kobj_type netdev_queue_ktype = {
         .sysfs_ops = &netdev_queue_sysfs_ops,
+#ifdef CONFIG_XPS
         .release = netdev_queue_release,
+#endif
         .default_attrs = netdev_queue_default_attrs,
 };
 
@@ -1103,12 +1128,12 @@ static int netdev_queue_add_kobject(struct net_device *net, int index)
 
         return error;
 }
-#endif /* CONFIG_XPS */
+#endif /* CONFIG_SYSFS */
 
 int
 netdev_queue_update_kobjects(struct net_device *net, int old_num, int new_num)
 {
-#ifdef CONFIG_XPS
+#ifdef CONFIG_SYSFS
         int i;
         int error = 0;
 
@@ -1126,14 +1151,14 @@ netdev_queue_update_kobjects(struct net_device *net, int old_num, int new_num)
         return error;
 #else
         return 0;
-#endif
+#endif /* CONFIG_SYSFS */
 }
 
 static int register_queue_kobjects(struct net_device *net)
 {
         int error = 0, txq = 0, rxq = 0, real_rx = 0, real_tx = 0;
 
-#if defined(CONFIG_RPS) || defined(CONFIG_XPS)
+#ifdef CONFIG_SYSFS
         net->queues_kset = kset_create_and_add("queues",
             NULL, &net->dev.kobj);
         if (!net->queues_kset)
@@ -1174,7 +1199,7 @@ static void remove_queue_kobjects(struct net_device *net)
 
         net_rx_queue_update_kobjects(net, real_rx, 0);
         netdev_queue_update_kobjects(net, real_tx, 0);
-#if defined(CONFIG_RPS) || defined(CONFIG_XPS)
+#ifdef CONFIG_SYSFS
         kset_unregister(net->queues_kset);
 #endif
 }
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index b4c680900d7..06d8a8fec68 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -246,6 +246,7 @@ static void dev_watchdog(unsigned long arg)
                                     time_after(jiffies, (trans_start +
                                                          dev->watchdog_timeo))) {
                                         some_queue_timedout = 1;
+                                        txq->trans_timeout++;
                                         break;
                                 }
                         }