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Merge branch 'net-mlx5e-prevent-stale-xsk-buffer-release-on-refill-retries'

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Jerome Tollet says:

====================
net/mlx5e: Prevent stale XSK buffer release on refill retries

Prevent duplicate XSK buffer release when a deferred RX refill fails and
the same WQE is retried.

Patch 1 fixes legacy cyclic RQ. It is unchanged from v3 and retains
Dragos' Reviewed-by tag.

Patch 2 fixes the analogous striding-RQ MPWQE path. Following Dragos'
review, it now fills skip_release_bitmap in the common error path of
mlx5e_xsk_alloc_rx_mpwqe(), consistently with mlx5e_alloc_rx_mpwqe().

Targeted fault injection covered both an early allocation failure and a
partial 8-of-16-buffer unwind. With three consecutive failures for one
MPWQE, the original 16 XSK buffers were released only once, retries saw a
full bitmap, and a later successful allocation cleared it. A clean
20-second AF_XDP zero-copy pressure run exercised 1,575,262 buffer
allocation failures without invalid descriptors, WQE errors, or kernel
warnings.
====================

Link: https://patch.msgid.link/20260824141645.23700-1-jtollet@cisco.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski 2026-08-28 15:39:17 -07:00
commit b873bf8141
2 changed files with 7 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/net/ethernet/mellanox/mlx5/core/en/xsk/rx.c
View File

@ -3,6 +3,7 @@
#include "rx.h"
#include "en/xdp.h"
#include <linux/bitmap.h>
#include <net/xdp_sock_drv.h>
#include <linux/filter.h>
@ -156,6 +157,7 @@ int mlx5e_xsk_alloc_rx_mpwqe(struct mlx5e_rq *rq, u16 ix)
xsk_buff_free(xsk_buffs[batch]);
err:
bitmap_fill(wi->skip_release_bitmap, rq->mpwqe.pages_per_wqe);
rq->stats->buff_alloc_err++;
return -ENOMEM;
}

7
drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
View File

@ -410,8 +410,11 @@ static inline void mlx5e_free_rx_wqe(struct mlx5e_rq *rq,
static void mlx5e_xsk_free_rx_wqe(struct mlx5e_wqe_frag_info *wi)
{
if (!(wi->flags & BIT(MLX5E_WQE_FRAG_SKIP_RELEASE)))
xsk_buff_free(*wi->xskp);
if (wi->flags & BIT(MLX5E_WQE_FRAG_SKIP_RELEASE))
return;
xsk_buff_free(*wi->xskp);
wi->flags |= BIT(MLX5E_WQE_FRAG_SKIP_RELEASE);
}
static void mlx5e_dealloc_rx_wqe(struct mlx5e_rq *rq, u16 ix)