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Message-ID: <20250506110546.4065715-3-m-malladi@ti.com>
Date: Tue, 6 May 2025 16:35:45 +0530
From: Meghana Malladi <m-malladi@...com>
To: <namcao@...utronix.de>, <horms@...nel.org>, <m-malladi@...com>,
<john.fastabend@...il.com>, <hawk@...nel.org>, <daniel@...earbox.net>,
<ast@...nel.org>, <pabeni@...hat.com>, <kuba@...nel.org>,
<edumazet@...gle.com>, <davem@...emloft.net>, <andrew+netdev@...n.ch>
CC: <bpf@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<netdev@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
<srk@...com>, Vignesh Raghavendra <vigneshr@...com>,
Roger Quadros
<rogerq@...nel.org>, <danishanwar@...com>
Subject: [PATCH net v2 2/3] net: ti: icssg-prueth: Fix kernel panic during concurrent Tx queue access
Add __netif_tx_lock() to ensure that only one packet is being
transmitted at a time to avoid race conditions in the netif_txq
struct and prevent packet data corruption. Failing to do so causes
kernel panic with the following error:
[ 2184.746764] ------------[ cut here ]------------
[ 2184.751412] kernel BUG at lib/dynamic_queue_limits.c:99!
[ 2184.756728] Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
logs: https://gist.github.com/MeghanaMalladiTI/9c7aa5fc3b7fb03f87c74aad487956e9
The lock is acquired before calling emac_xmit_xdp_frame() and released after the
call returns. This ensures that the TX queue is protected from concurrent access
during the transmission of XDP frames.
Fixes: 62aa3246f462 ("net: ti: icssg-prueth: Add XDP support")
Signed-off-by: Meghana Malladi <m-malladi@...com>
---
Changes from v1 (v2-v1):
- Move netif_tx_lock/unlock outside of the loop, reported by Jesper Dangaard Brouer <hawk@...nel.org>
drivers/net/ethernet/ti/icssg/icssg_common.c | 7 ++++++-
drivers/net/ethernet/ti/icssg/icssg_prueth.c | 7 ++++++-
2 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/ti/icssg/icssg_common.c b/drivers/net/ethernet/ti/icssg/icssg_common.c
index 79f2d86acf21..36d5cb25c017 100644
--- a/drivers/net/ethernet/ti/icssg/icssg_common.c
+++ b/drivers/net/ethernet/ti/icssg/icssg_common.c
@@ -650,6 +650,8 @@ static u32 emac_run_xdp(struct prueth_emac *emac, struct xdp_buff *xdp,
struct page *page, u32 *len)
{
struct net_device *ndev = emac->ndev;
+ struct netdev_queue *netif_txq;
+ int cpu = smp_processor_id();
struct bpf_prog *xdp_prog;
struct xdp_frame *xdpf;
u32 pkt_len = *len;
@@ -669,8 +671,11 @@ static u32 emac_run_xdp(struct prueth_emac *emac, struct xdp_buff *xdp,
goto drop;
}
- q_idx = smp_processor_id() % emac->tx_ch_num;
+ q_idx = cpu % emac->tx_ch_num;
+ netif_txq = netdev_get_tx_queue(ndev, q_idx);
+ __netif_tx_lock(netif_txq, cpu);
result = emac_xmit_xdp_frame(emac, xdpf, page, q_idx);
+ __netif_tx_unlock(netif_txq);
if (result == ICSSG_XDP_CONSUMED) {
ndev->stats.tx_dropped++;
goto drop;
diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth.c b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
index ee35fecf61e7..86fc1278127c 100644
--- a/drivers/net/ethernet/ti/icssg/icssg_prueth.c
+++ b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
@@ -1075,17 +1075,21 @@ static int emac_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frame
{
struct prueth_emac *emac = netdev_priv(dev);
struct net_device *ndev = emac->ndev;
+ struct netdev_queue *netif_txq;
+ int cpu = smp_processor_id();
struct xdp_frame *xdpf;
unsigned int q_idx;
int nxmit = 0;
u32 err;
int i;
- q_idx = smp_processor_id() % emac->tx_ch_num;
+ q_idx = cpu % emac->tx_ch_num;
+ netif_txq = netdev_get_tx_queue(ndev, q_idx);
if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK))
return -EINVAL;
+ __netif_tx_lock(netif_txq, cpu);
for (i = 0; i < n; i++) {
xdpf = frames[i];
err = emac_xmit_xdp_frame(emac, xdpf, NULL, q_idx);
@@ -1095,6 +1099,7 @@ static int emac_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frame
}
nxmit++;
}
+ __netif_tx_unlock(netif_txq);
return nxmit;
}
--
2.43.0
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