[PATCH net 3/3] bnxt_en: Prevent XDP redirect from running when stopping TX queue

[Michael Chan <michael.chan@broadcom.com>]

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From: Ray Jui <ray.jui@broadcom.com>

Add checks in the XDP redirect callback to prevent XDP from running when
the TX ring is undergoing shutdown.

Also remove redundant checks in the XDP redirect callback to validate the
txr and the flag that indicates the ring supports XDP. The modulo
arithmetic on 'tx_nr_rings_xdp' already guarantees the derived TX
ring is an XDP ring.  txr is also guaranteed to be valid after checking
BNXT_STATE_OPEN and within RCU grace period.

Fixes: f18c2b77b2e4 ("bnxt_en: optimized XDP_REDIRECT support")
Reviewed-by: Vladimir Olovyannikov <vladimir.olovyannikov@broadcom.com>
Signed-off-by: Ray Jui <ray.jui@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c
index c0541ff00ac8..03b1d6c04504 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c
@@ -229,14 +229,16 @@ int bnxt_xdp_xmit(struct net_device *dev, int num_frames,
 	ring = smp_processor_id() % bp->tx_nr_rings_xdp;
 	txr = &bp->tx_ring[ring];
 
+	if (READ_ONCE(txr->dev_state) == BNXT_DEV_STATE_CLOSING)
+		return -EINVAL;
+
 	if (static_branch_unlikely(&bnxt_xdp_locking_key))
 		spin_lock(&txr->xdp_tx_lock);
 
 	for (i = 0; i < num_frames; i++) {
 		struct xdp_frame *xdp = frames[i];
 
-		if (!txr || !bnxt_tx_avail(bp, txr) ||
-		    !(bp->bnapi[ring]->flags & BNXT_NAPI_FLAG_XDP))
+		if (!bnxt_tx_avail(bp, txr))
 			break;
 
 		mapping = dma_map_single(&pdev->dev, xdp->data, xdp->len,
-- 
2.18.1


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