[PATCH v2 2/2] net: io_uring/zcrx: call netdev_queue_get_dma_dev() under instance lock
From: David Wei <hidden>
Date: 2025-10-29 23:16:58
Also in:
io-uring
Subsystem:
io_uring, io_uring zcrx, the rest · Maintainers:
Jens Axboe, Pavel Begunkov, Linus Torvalds
netdev ops must be called under instance lock or rtnl_lock, but
io_register_zcrx_ifq() isn't doing this for netdev_queue_get_dma_dev().
Fix this by taking the instance lock using netdev_get_by_index_lock().
Extended the instance lock section to include attaching a memory
provider. Could not move io_zcrx_create_area() outside, since the dmabuf
codepath IORING_ZCRX_AREA_DMABUF requires ifq->dev.
Fixes: 59b8b32ac8d4 ("io_uring/zcrx: add support for custom DMA devices")
Signed-off-by: David Wei <redacted>
---
io_uring/zcrx.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index a816f5902091..5599883f8941 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c@@ -599,27 +599,28 @@ int io_register_zcrx_ifq(struct io_ring_ctx *ctx, if (ret) goto err; - ifq->netdev = netdev_get_by_index(current->nsproxy->net_ns, reg.if_idx, - &ifq->netdev_tracker, GFP_KERNEL); + ifq->netdev = netdev_get_by_index_lock(current->nsproxy->net_ns, reg.if_idx); if (!ifq->netdev) { ret = -ENODEV; - goto err; + goto netdev_unlock; } ifq->dev = netdev_queue_get_dma_dev(ifq->netdev, reg.if_rxq); if (!ifq->dev) { ret = -EOPNOTSUPP; - goto err; + goto netdev_unlock; } + netdev_hold(ifq->netdev, &ifq->netdev_tracker, GFP_KERNEL); get_device(ifq->dev); ret = io_zcrx_create_area(ifq, &area); if (ret) - goto err; + goto netdev_unlock; mp_param.mp_ops = &io_uring_pp_zc_ops; mp_param.mp_priv = ifq; - ret = net_mp_open_rxq(ifq->netdev, reg.if_rxq, &mp_param); + ret = __net_mp_open_rxq(ifq->netdev, reg.if_rxq, &mp_param, NULL); + netdev_unlock(ifq->netdev); if (ret) goto err; ifq->if_rxq = reg.if_rxq;
@@ -640,6 +641,8 @@ int io_register_zcrx_ifq(struct io_ring_ctx *ctx, goto err; } return 0; +netdev_unlock: + netdev_unlock(ifq->netdev); err: scoped_guard(mutex, &ctx->mmap_lock) xa_erase(&ctx->zcrx_ctxs, id);
--
2.47.3