[dpdk-stable] [PATCH] net/ixgbe: fix link state timing issue on fiber ports

[Phil Yang <phil.yang@arm.com>]

With some models of fiber ports (e.g. X520-2 device ID 0x10fb), it
is possible when a port is started to experience a timing issue
which prevents the link from ever being fully set up.

In ixgbe_dev_link_update_share(), if the media type is fiber and the
link is down, a flag (IXGBE_FLAG_NEED_LINK_CONFIG) is set. A callback
to ixgbe_dev_setup_link_thread_handler() is scheduled which should
try to set up the link and clear the flag afterwards.

If the device is started before the flag is cleared, the scheduled
callback is cancelled. This causes the flag to remain set and
subsequent calls to ixgbe_dev_link_update_share() return
without trying to retrieve the link state because the flag is set.

In ixgbe_dev_cancel_link_thread(), after cancelling the callback,
unset the flag on the device to avoid this condition.

Fixes: 819d0d1d57f1 ("net/ixgbe: fix blocking system events")
Cc: stable@dpdk.org

Bugzilla ID: 388

Signed-off-by: Phil Yang <phil.yang@arm.com>
Signed-off-by: Lijian Zhang <lijian.zhang@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>
---
 drivers/net/ixgbe/ixgbe_ethdev.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ixgbe/ixgbe_ethdev.c b/drivers/net/ixgbe/ixgbe_ethdev.c
index 23b3f5b..2b65750 100644
--- a/drivers/net/ixgbe/ixgbe_ethdev.c
+++ b/drivers/net/ixgbe/ixgbe_ethdev.c
@@ -4147,11 +4147,19 @@ static void
 ixgbe_dev_cancel_link_thread(struct rte_eth_dev *dev)
 {
 	struct ixgbe_adapter *ad = dev->data->dev_private;
+	struct ixgbe_interrupt *intr =
+		IXGBE_DEV_PRIVATE_TO_INTR(dev->data->dev_private);
 	void *retval;
 
 	if (rte_atomic32_read(&ad->link_thread_running)) {
 		pthread_cancel(ad->link_thread_tid);
 		pthread_join(ad->link_thread_tid, &retval);
+		/* clear this flag once the thread has been
+		 * cancelled, to avoid link status error in
+		 * case unfinished threads cannot clean up
+		 * this flag.
+		 */
+		intr->flags &= ~IXGBE_FLAG_NEED_LINK_CONFIG;
 		rte_atomic32_clear(&ad->link_thread_running);
 	}
 }
@@ -4262,8 +4270,12 @@ ixgbe_dev_link_update_share(struct rte_eth_dev *dev,
 
 	if (link_up == 0) {
 		if (ixgbe_get_media_type(hw) == ixgbe_media_type_fiber) {
-			intr->flags |= IXGBE_FLAG_NEED_LINK_CONFIG;
 			if (rte_atomic32_test_and_set(&ad->link_thread_running)) {
+				/* To avoid race condition between threads, set
+				 * the IXGBE_FLAG_NEED_LINK_CONFIG flag only
+				 * when there is no link thread running.
+				 */
+				intr->flags |= IXGBE_FLAG_NEED_LINK_CONFIG;
 				if (rte_ctrl_thread_create(&ad->link_thread_tid,
 					"ixgbe-link-handler",
 					NULL,
-- 
2.7.4