[PATCH 6.18 110/227] idpf: Fix data race in idpf_net_dim

Greg Kroah-Hartman
2026-01-28T15:56:12Z

From: David Yang <mmyangfl@gmail.com>

[ Upstream commit 5fbe395cd1fdbc883584e7f38369e4ba5ca778d2 ]

In idpf_net_dim(), some statistics protected by u64_stats_sync, are read
and accumulated in ignorance of possible u64_stats_fetch_retry() events.
The correct way to copy statistics is already illustrated by
idpf_add_queue_stats(). Fix this by reading them into temporary variables
first.

Fixes: c2d548cad150 ("idpf: add TX splitq napi poll support")
Fixes: 3a8845af66ed ("idpf: add RX splitq napi poll support")
Signed-off-by: David Yang <mmyangfl@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260119162720.1463859-1-mmyangfl@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/intel/idpf/idpf_txrx.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.c b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
index f66948f5de78b..a48088eb9b822 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
@@ -3941,7 +3941,7 @@ static void idpf_update_dim_sample(struct idpf_q_vector *q_vector,
static void idpf_net_dim(struct idpf_q_vector *q_vector)
{
struct dim_sample dim_sample = { };
- u64 packets, bytes;
+ u64 packets, bytes, pkts, bts;
u32 i;

if (!IDPF_ITR_IS_DYNAMIC(q_vector->tx_intr_mode))
@@ -3953,9 +3953,12 @@ static void idpf_net_dim(struct idpf_q_vector *q_vector)

do {
start = u64_stats_fetch_begin(&txq->stats_sync);
- packets += u64_stats_read(&txq->q_stats.packets);
- bytes += u64_stats_read(&txq->q_stats.bytes);
+ pkts = u64_stats_read(&txq->q_stats.packets);
+ bts = u64_stats_read(&txq->q_stats.bytes);
} while (u64_stats_fetch_retry(&txq->stats_sync, start));
+
+ packets += pkts;
+ bytes += bts;
}

idpf_update_dim_sample(q_vector, &dim_sample, &q_vector->tx_dim,
@@ -3972,9 +3975,12 @@ static void idpf_net_dim(struct idpf_q_vector *q_vector)

do {
start = u64_stats_fetch_begin(&rxq->stats_sync);
- packets += u64_stats_read(&rxq->q_stats.packets);
- bytes += u64_stats_read(&rxq->q_stats.bytes);
+ pkts = u64_stats_read(&rxq->q_stats.packets);
+ bts = u64_stats_read(&rxq->q_stats.bytes);
} while (u64_stats_fetch_retry(&rxq->stats_sync, start));
+
+ packets += pkts;
+ bytes += bts;
}

idpf_update_dim_sample(q_vector, &dim_sample, &q_vector->rx_dim,
--
2.51.0