From: Pavan Chebbi <pavan.chebbi@broadcom.com>
Date: Fri, 1 Apr 2022 20:21:10 -0400
Subject: bnxt_en: Synchronize tx when xdp redirects happen on same ring
Patch-mainline: v5.18-rc2
Git-commit: 4f81def272de17dc4bbd89ac38f49b2676c9b3d2
References: git-fixes

If there are more CPUs than the number of TX XDP rings, multiple XDP
redirects can select the same TX ring based on the CPU on which
XDP redirect is called.  Add locking when needed and use static
key to decide whether to take the lock.

Fixes: f18c2b77b2e4 ("bnxt_en: optimized XDP_REDIRECT support")
Signed-off-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c     |    7 +++++++
 drivers/net/ethernet/broadcom/bnxt/bnxt.h     |    2 ++
 drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c |    8 ++++++++
 drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.h |    2 ++
 4 files changed, 19 insertions(+)

--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -3196,6 +3196,7 @@ static int bnxt_alloc_tx_rings(struct bn
 		}
 		qidx = bp->tc_to_qidx[j];
 		ring->queue_id = bp->q_info[qidx].queue_id;
+		spin_lock_init(&txr->xdp_tx_lock);
 		if (i < bp->tx_nr_rings_xdp)
 			continue;
 		if (i % bp->tx_nr_rings_per_tc == (bp->tx_nr_rings_per_tc - 1))
@@ -10274,6 +10275,12 @@ static int __bnxt_open_nic(struct bnxt *
 	if (irq_re_init)
 		udp_tunnel_nic_reset_ntf(bp->dev);
 
+	if (bp->tx_nr_rings_xdp < num_possible_cpus()) {
+		if (!static_key_enabled(&bnxt_xdp_locking_key))
+			static_branch_enable(&bnxt_xdp_locking_key);
+	} else if (static_key_enabled(&bnxt_xdp_locking_key)) {
+		static_branch_disable(&bnxt_xdp_locking_key);
+	}
 	set_bit(BNXT_STATE_OPEN, &bp->state);
 	bnxt_enable_int(bp);
 	/* Enable TX queues */
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
@@ -800,6 +800,8 @@ struct bnxt_tx_ring_info {
 	u32			dev_state;
 
 	struct bnxt_ring_struct	tx_ring_struct;
+	/* Synchronize simultaneous xdp_xmit on same ring */
+	spinlock_t		xdp_tx_lock;
 };
 
 #define BNXT_LEGACY_COAL_CMPL_PARAMS					\
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c
@@ -20,6 +20,8 @@
 #include "bnxt.h"
 #include "bnxt_xdp.h"
 
+DEFINE_STATIC_KEY_FALSE(bnxt_xdp_locking_key);
+
 struct bnxt_sw_tx_bd *bnxt_xmit_bd(struct bnxt *bp,
 				   struct bnxt_tx_ring_info *txr,
 				   dma_addr_t mapping, u32 len)
@@ -227,6 +229,9 @@ int bnxt_xdp_xmit(struct net_device *dev
 	ring = smp_processor_id() % bp->tx_nr_rings_xdp;
 	txr = &bp->tx_ring[ring];
 
+	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];
 
@@ -250,6 +255,9 @@ int bnxt_xdp_xmit(struct net_device *dev
 		bnxt_db_write(bp, &txr->tx_db, txr->tx_prod);
 	}
 
+	if (static_branch_unlikely(&bnxt_xdp_locking_key))
+		spin_unlock(&txr->xdp_tx_lock);
+
 	return nxmit;
 }
 
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.h
@@ -10,6 +10,8 @@
 #ifndef BNXT_XDP_H
 #define BNXT_XDP_H
 
+DECLARE_STATIC_KEY_FALSE(bnxt_xdp_locking_key);
+
 struct bnxt_sw_tx_bd *bnxt_xmit_bd(struct bnxt *bp,
 				   struct bnxt_tx_ring_info *txr,
 				   dma_addr_t mapping, u32 len);