netdev - [PATCH net 1/2] ionic: add LIF_READY state to close probe-open race

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Message-Id: <20200429183739.56540-2-snelson@pensando.io>
Date:   Wed, 29 Apr 2020 11:37:38 -0700
From:   Shannon Nelson <snelson@...sando.io>
To:     netdev@...r.kernel.org, davem@...emloft.net
Cc:     Shannon Nelson <snelson@...sando.io>
Subject: [PATCH net 1/2] ionic: add LIF_READY state to close probe-open race

Add a bit of state to the lif to signify when the queues are
ready to be used.  This closes an ionic_probe()/ionic_open()
race condition where the driver has registered the netdev
and signaled Link Up while running under ionic_probe(),
which NetworkManager or other user processes can see and then
try to bring up the device before the initial pass through
ionic_link_status_check() has finished.  NetworkManager's
thread can get into __dev_open() and set __LINK_STATE_START
in dev->state before the ionic_probe() thread makes it to the
netif_running() check, which results in the ionic_probe() thread
trying to start the queues before the queues have completed
their initialization.

Adding a LIF_QREADY flag allows us to prevent this condition by
signaling whether the Tx/Rx queues are initialized and ready.

Fixes: c672412f6172 ("ionic: remove lifs on fw reset")
Signed-off-by: Shannon Nelson <snelson@...sando.io>
---
 drivers/net/ethernet/pensando/ionic/ionic_lif.c |  6 ++++++
 drivers/net/ethernet/pensando/ionic/ionic_lif.h | 11 +++++++++++
 2 files changed, 17 insertions(+)

diff --git a/drivers/net/ethernet/pensando/ionic/ionic_lif.c b/drivers/net/ethernet/pensando/ionic/ionic_lif.c
index 5acf4f46c268..2dc513f43fd4 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_lif.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_lif.c
@@ -1627,6 +1627,9 @@ static int ionic_start_queues(struct ionic_lif *lif)
 {
 	int err;
 
+	if (!test_bit(IONIC_LIF_F_QREADY, lif->state))
+		return 0;
+
 	if (test_and_set_bit(IONIC_LIF_F_UP, lif->state))
 		return 0;
 
@@ -1652,6 +1655,7 @@ int ionic_open(struct net_device *netdev)
 	err = ionic_txrx_init(lif);
 	if (err)
 		goto err_out;
+	set_bit(IONIC_LIF_F_QREADY, lif->state);
 
 	/* don't start the queues until we have link */
 	if (netif_carrier_ok(netdev)) {
@@ -1663,6 +1667,7 @@ int ionic_open(struct net_device *netdev)
 	return 0;
 
 err_txrx_deinit:
+	clear_bit(IONIC_LIF_F_QREADY, lif->state);
 	ionic_txrx_deinit(lif);
 err_out:
 	ionic_txrx_free(lif);
@@ -1685,6 +1690,7 @@ int ionic_stop(struct net_device *netdev)
 	if (test_bit(IONIC_LIF_F_FW_RESET, lif->state))
 		return 0;
 
+	clear_bit(IONIC_LIF_F_QREADY, lif->state);
 	ionic_stop_queues(lif);
 	ionic_txrx_deinit(lif);
 	ionic_txrx_free(lif);
diff --git a/drivers/net/ethernet/pensando/ionic/ionic_lif.h b/drivers/net/ethernet/pensando/ionic/ionic_lif.h
index 5d4ffda5c05f..a7bf85c17354 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_lif.h
+++ b/drivers/net/ethernet/pensando/ionic/ionic_lif.h
@@ -121,9 +121,20 @@ struct ionic_lif_sw_stats {
 	u64 rx_csum_error;
 };
 
+/**
+ * enum ionic_lif_state_flags - driver LIF states
+ * @IONIC_LIF_F_INITED:		LIF configured, adminq running
+ * @IONIC_LIF_F_SW_DEBUG_STATS:	Ethtool printing of extra stats is enabled
+ * @IONIC_LIF_F_QREADY:		LIF queues are configured and ready for UP
+ * @IONIC_LIF_F_UP:		LIF is fully UP and running
+ * @IONIC_LIF_F_LINK_CHECK_REQUESTED:	Link check has been requested
+ * @IONIC_LIF_F_QUEUE_RESET:	LIF is resetting all queues
+ * @IONIC_LIF_F_FW_RESET:	FW is going through reset
+ */
 enum ionic_lif_state_flags {
 	IONIC_LIF_F_INITED,
 	IONIC_LIF_F_SW_DEBUG_STATS,
+	IONIC_LIF_F_QREADY,
 	IONIC_LIF_F_UP,
 	IONIC_LIF_F_LINK_CHECK_REQUESTED,
 	IONIC_LIF_F_QUEUE_RESET,
-- 
2.17.1