[PATCH net-next v1] net: gro_cells: move backlog drop handling outside the local lock
From: Xuanqiang Luo <hidden>
Date: 2026-09-15 12:16:15
Also in:
lkml
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: Xuanqiang Luo <redacted> When the GRO cell queue length exceeds max_backlog, gro_cells_receive() holds bh_lock while updating the RX drop counter and freeing the rejected skb. The skb has not been queued, and the counter is updated with this_cpu_inc(), so neither operation requires the queue lock. Release bh_lock before accounting for and freeing the dropped skb to shorten the critical section. Signed-off-by: Xuanqiang Luo <redacted> --- net/core/gro_cells.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/net/core/gro_cells.c b/net/core/gro_cells.c
index d8c0a28671201..f46cecd246aab 100644
--- a/net/core/gro_cells.c
+++ b/net/core/gro_cells.c@@ -14,7 +14,6 @@ struct gro_cell { int gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb) { struct net_device *dev = skb->dev; - bool have_bh_lock = false; struct gro_cell *cell; int res;
@@ -26,32 +25,33 @@ int gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb) if (!gcells->cells || skb_cloned(skb) || netif_elide_gro(dev)) { res = netif_rx(skb); - goto unlock; + goto out_rcu; } local_lock_nested_bh(&gcells->cells->bh_lock); - have_bh_lock = true; cell = this_cpu_ptr(gcells->cells); - if (skb_queue_len(&cell->napi_skbs) > READ_ONCE(net_hotdata.max_backlog)) { -drop: - dev_core_stats_rx_dropped_inc(dev); - kfree_skb(skb); - res = NET_RX_DROP; + if (skb_queue_len(&cell->napi_skbs) > READ_ONCE(net_hotdata.max_backlog)) goto unlock; - } __skb_queue_tail(&cell->napi_skbs, skb); if (skb_queue_len(&cell->napi_skbs) == 1) napi_schedule(&cell->napi); + local_unlock_nested_bh(&gcells->cells->bh_lock); res = NET_RX_SUCCESS; -unlock: - if (have_bh_lock) - local_unlock_nested_bh(&gcells->cells->bh_lock); +out_rcu: rcu_read_unlock(); return res; + +unlock: + local_unlock_nested_bh(&gcells->cells->bh_lock); +drop: + dev_core_stats_rx_dropped_inc(dev); + kfree_skb(skb); + res = NET_RX_DROP; + goto out_rcu; } EXPORT_SYMBOL(gro_cells_receive);
base-commit: 1142eb185b05db61a78130890fc4ed268f4cb4e6 -- 2.43.0