[PATCH] net: macb: Change interrupt and napi enable order in open

From: Harini Katakam <harini.katakam@xilinx.com>
To: <nicolas.ferre@microchip.com>, <davem@davemloft.net>,
	<rafalo@cadence.com>
Cc: <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<michal.simek@xilinx.com>, <harinikatakamlinux@gmail.com>,
	<harini.katakam@xilinx.com>
Subject: [PATCH] net: macb: Change interrupt and napi enable order in open
Date: Tue, 7 May 2019 19:59:10 +0530	[thread overview]
Message-ID: <1557239350-4760-1-git-send-email-harini.katakam@xilinx.com> (raw)

Current order in open:
-> Enable interrupts (macb_init_hw)
-> Enable NAPI
-> Start PHY

Sequence of RX handling:
-> RX interrupt occurs
-> Interrupt is cleared and interrupt bits disabled in handler
-> NAPI is scheduled
-> In NAPI, RX budget is processed and RX interrupts are re-enabled

With the above, on QEMU or fixed link setups (where PHY state doesn't
matter), there's a chance macb RX interrupt occurs before NAPI is
enabled. This will result in NAPI being scheduled before it is enabled.
Fix this macb open by changing the order.

Fixes: ae1f2a56d273 ("net: macb: Added support for many RX queues")
Signed-off-by: Harini Katakam <harini.katakam@xilinx.com>
---
 drivers/net/ethernet/cadence/macb_main.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 5d5c9d7..c049410 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -2427,12 +2427,12 @@ static int macb_open(struct net_device *dev)
 		goto pm_exit;
 	}
 
-	bp->macbgem_ops.mog_init_rings(bp);
-	macb_init_hw(bp);
-
 	for (q = 0, queue = bp->queues; q < bp->num_queues; ++q, ++queue)
 		napi_enable(&queue->napi);
 
+	bp->macbgem_ops.mog_init_rings(bp);
+	macb_init_hw(bp);
+
 	/* schedule a link state check */
 	phy_start(dev->phydev);
 
-- 
2.7.4

