[PATCH net-next 1/3] net: Introduce netif_xmit_time_out_duration() helper

[Tariq Toukan <tariqt@nvidia.com>]

From: Shahar Shitrit <shshitrit@nvidia.com>

Introduce a new helper function netif_xmit_time_out_duration() to
check if a TX queue has timed out and report the timeout duration.
This helper consolidates the logic that is duplicated in several
locations and also encapsulates the check for whether the TX queue
is stopped.

As the first user, convert dev_watchdog() to use this helper.

Signed-off-by: Shahar Shitrit <shshitrit@nvidia.com>
Reviewed-by: Yael Chemla <ychemla@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 include/linux/netdevice.h | 15 +++++++++++++++
 net/sched/sch_generic.c   |  7 +++----
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index e808071dbb7d..3cd73769fcfa 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3680,6 +3680,21 @@ static inline bool netif_xmit_stopped(const struct netdev_queue *dev_queue)
 	return dev_queue->state & QUEUE_STATE_ANY_XOFF;
 }
 
+static inline unsigned int
+netif_xmit_timeout_ms(struct netdev_queue *txq, unsigned long *trans_start)
+{
+	unsigned long txq_trans_start = READ_ONCE(txq->trans_start);
+
+	if (trans_start)
+		*trans_start = txq_trans_start;
+
+	if (netif_xmit_stopped(txq) &&
+	    time_after(jiffies, txq_trans_start + txq->dev->watchdog_timeo))
+		return jiffies_to_msecs(jiffies - txq_trans_start);
+
+	return 0;
+}
+
 static inline bool
 netif_xmit_frozen_or_stopped(const struct netdev_queue *dev_queue)
 {
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 852e603c1755..aa6192781a24 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -523,10 +523,9 @@ static void dev_watchdog(struct timer_list *t)
 				 * netdev_tx_sent_queue() and netif_tx_stop_queue().
 				 */
 				smp_mb();
-				trans_start = READ_ONCE(txq->trans_start);
-
-				if (time_after(jiffies, trans_start + dev->watchdog_timeo)) {
-					timedout_ms = jiffies_to_msecs(jiffies - trans_start);
+				timedout_ms = netif_xmit_timeout_ms(txq,
+								    &trans_start);
+				if (timedout_ms) {
 					atomic_long_inc(&txq->trans_timeout);
 					break;
 				}
-- 
2.31.1