[Intel-wired-lan] [PATCH iwl-next v6 1/6] igb: Always call igb_xdp_ring_update_tail() under Tx lock

[Kurt Kanzenbach]

From: Sriram Yagnaraman <sriram.yagnara...@est.tech>

Always call igb_xdp_ring_update_tail() under __netif_tx_lock(), add a
comment to indicate that. This is needed to share the same TX ring between
XDP, XSK and slow paths.

Signed-off-by: Sriram Yagnaraman <sriram.yagnara...@est.tech>
[Kurt: Split patches]
Signed-off-by: Kurt Kanzenbach <k...@linutronix.de>
---
 drivers/net/ethernet/intel/igb/igb_main.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c 
b/drivers/net/ethernet/intel/igb/igb_main.c
index 11be39f435f3..4d5e5691c9bd 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -2914,6 +2914,7 @@ static int igb_xdp(struct net_device *dev, struct 
netdev_bpf *xdp)
        }
 }
 
+/* This function assumes __netif_tx_lock is held by the caller. */
 static void igb_xdp_ring_update_tail(struct igb_ring *ring)
 {
        /* Force memory writes to complete before letting h/w know there
@@ -3000,11 +3001,11 @@ static int igb_xdp_xmit(struct net_device *dev, int n,
                nxmit++;
        }
 
-       __netif_tx_unlock(nq);
-
        if (unlikely(flags & XDP_XMIT_FLUSH))
                igb_xdp_ring_update_tail(tx_ring);
 
+       __netif_tx_unlock(nq);
+
        return nxmit;
 }
 
@@ -8853,12 +8854,14 @@ static void igb_put_rx_buffer(struct igb_ring *rx_ring,
 
 static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
 {
+       unsigned int total_bytes = 0, total_packets = 0;
        struct igb_adapter *adapter = q_vector->adapter;
        struct igb_ring *rx_ring = q_vector->rx.ring;
-       struct sk_buff *skb = rx_ring->skb;
-       unsigned int total_bytes = 0, total_packets = 0;
        u16 cleaned_count = igb_desc_unused(rx_ring);
+       struct sk_buff *skb = rx_ring->skb;
+       int cpu = smp_processor_id();
        unsigned int xdp_xmit = 0;
+       struct netdev_queue *nq;
        struct xdp_buff xdp;
        u32 frame_sz = 0;
        int rx_buf_pgcnt;
@@ -8986,7 +8989,10 @@ static int igb_clean_rx_irq(struct igb_q_vector 
*q_vector, const int budget)
        if (xdp_xmit & IGB_XDP_TX) {
                struct igb_ring *tx_ring = igb_xdp_tx_queue_mapping(adapter);
 
+               nq = txring_txq(tx_ring);
+               __netif_tx_lock(nq, cpu);
                igb_xdp_ring_update_tail(tx_ring);
+               __netif_tx_unlock(nq);
        }
 
        u64_stats_update_begin(&rx_ring->rx_syncp);

-- 
2.39.2