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Thu, 17 Sep 2026 11:11:19 -0700 (PDT) Received: from localhost ([2a03:2880:2ff:59::]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-cc5256e04c7sm1192926a12.22.2026.09.17.11.11.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Sep 2026 11:11:18 -0700 (PDT) From: Stanislav Fomichev X-Google-Original-From: Stanislav Fomichev To: netdev@vger.kernel.org Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, sdf@fomichev.me, bobbyeshleman@meta.com, almasrymina@google.com, linux-kernel@vger.kernel.org Subject: [PATCH net-next v3 2/3] net: devmem: embed net_iov_area in binding Date: Thu, 17 Sep 2026 11:11:15 -0700 Message-ID: <20260917181116.3319017-3-sdf@fomichev.me> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260917181116.3319017-1-sdf@fomichev.me> References: <20260917181116.3319017-1-sdf@fomichev.me> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit After replacing the gen_pool with a binding-level freelist, devmem no longer needs a separate chunk owner object. There is only one net_iov_area for the binding, so store it directly in struct net_devmem_dmabuf_binding. Derive the binding from net_iov_owner() with container_of(), matching the pattern used by io_uring zcrx. This removes the leftover dmabuf_genpool_chunk_owner wrapper and its allocation/free path. Reviewed-by: Mina Almasry Signed-off-by: Stanislav Fomichev --- net/core/devmem.c | 61 ++++++++++++++--------------------------------- net/core/devmem.h | 25 +++++-------------- 2 files changed, 24 insertions(+), 62 deletions(-) diff --git a/net/core/devmem.c b/net/core/devmem.c index 2ac9d74010a9..7cac0dab8ea8 100644 --- a/net/core/devmem.c +++ b/net/core/devmem.c @@ -29,15 +29,6 @@ static DEFINE_XARRAY_FLAGS(net_devmem_dmabuf_bindings, XA_FLAGS_ALLOC1); static const struct memory_provider_ops dmabuf_devmem_ops; -static void -net_devmem_dmabuf_free_chunk_owner(struct dmabuf_genpool_chunk_owner *owner) -{ - if (owner) { - kvfree(owner->area.niovs); - kfree(owner); - } -} - static void net_devmem_dmabuf_binding_release(struct percpu_ref *ref) { struct net_devmem_dmabuf_binding *binding = @@ -52,12 +43,11 @@ void __net_devmem_dmabuf_binding_free(struct work_struct *wq) struct net_devmem_dmabuf_binding *binding = container_of(wq, typeof(*binding), unbind_w); if (binding->freelist) - WARN(binding->free_count != binding->chunk_owner->area.num_niovs, + WARN(binding->free_count != binding->area.num_niovs, "destroying dmabuf binding with outstanding net_iovs: total=%zu, free=%zu", - binding->chunk_owner->area.num_niovs, - binding->free_count); + binding->area.num_niovs, binding->free_count); - net_devmem_dmabuf_free_chunk_owner(binding->chunk_owner); + kvfree(binding->area.niovs); dma_buf_unmap_attachment_unlocked(binding->attachment, binding->sgt, binding->direction); dma_buf_detach(binding->dmabuf, binding->attachment); @@ -94,8 +84,7 @@ void net_devmem_free_dmabuf(struct net_iov *niov) struct net_devmem_dmabuf_binding *binding = net_devmem_iov_binding(niov); spin_lock_bh(&binding->freelist_lock); - if (WARN_ON_ONCE(binding->free_count >= - binding->chunk_owner->area.num_niovs)) { + if (WARN_ON_ONCE(binding->free_count >= binding->area.num_niovs)) { spin_unlock_bh(&binding->freelist_lock); return; } @@ -175,13 +164,11 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev, struct netlink_ext_ack *extack) { struct net_devmem_dmabuf_binding *binding; - struct dmabuf_genpool_chunk_owner *owner; size_t niov_size = 1UL << niov_shift; static u32 id_alloc_next; struct scatterlist *sg; struct dma_buf *dmabuf; unsigned int sg_idx; - size_t total_niovs; size_t niov_idx; size_t i; int err; @@ -241,16 +228,18 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev, goto err_unmap; } - total_niovs = dmabuf->size >> niov_shift; + binding->area.base_virtual = 0; + binding->area.num_niovs = dmabuf->size >> niov_shift; if (direction == DMA_TO_DEVICE) { - binding->tx_vec = kvmalloc_objs(struct net_iov *, total_niovs); + binding->tx_vec = kvmalloc_objs(struct net_iov *, + binding->area.num_niovs); if (!binding->tx_vec) { err = -ENOMEM; goto err_unmap; } } else { spin_lock_init(&binding->freelist_lock); - binding->freelist = kvmalloc_array(total_niovs, + binding->freelist = kvmalloc_array(binding->area.num_niovs, sizeof(binding->freelist[0]), GFP_KERNEL); if (!binding->freelist) { @@ -258,24 +247,13 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev, goto err_unmap; } } - owner = kzalloc_node(sizeof(*owner), GFP_KERNEL, - dev_to_node(&dev->dev)); - if (!owner) { + binding->area.niovs = kvmalloc_objs(*binding->area.niovs, + binding->area.num_niovs); + if (!binding->area.niovs) { err = -ENOMEM; goto err_free_freelist; } - owner->area.base_virtual = 0; - owner->area.num_niovs = total_niovs; - owner->binding = binding; - owner->area.niovs = kvmalloc_objs(*owner->area.niovs, - owner->area.num_niovs); - if (!owner->area.niovs) { - err = -ENOMEM; - goto err_free_owner; - } - binding->chunk_owner = owner; - niov_idx = 0; for_each_sgtable_dma_sg(binding->sgt, sg, sg_idx) { dma_addr_t dma_addr = sg_dma_address(sg); @@ -289,13 +267,13 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev, NL_SET_ERR_MSG_FMT(extack, "dmabuf sg entry (addr=%pad, len=%zu) not aligned to niov size %zu", &dma_addr, len, niov_size); - goto err_free_chunk_owner; + goto err_free_niovs; } nr_niovs = len >> niov_shift; for (i = 0; i < nr_niovs; i++, niov_idx++) { - niov = &owner->area.niovs[niov_idx]; - net_iov_init(niov, &owner->area, NET_IOV_DMABUF); + niov = &binding->area.niovs[niov_idx]; + net_iov_init(niov, &binding->area, NET_IOV_DMABUF); page_pool_set_dma_addr_netmem(net_iov_to_netmem(niov), dma_addr); if (direction == DMA_TO_DEVICE) @@ -310,17 +288,14 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev, binding, xa_limit_32b, &id_alloc_next, GFP_KERNEL); if (err < 0) - goto err_free_chunk_owner; + goto err_free_niovs; list_add(&binding->list, &priv->bindings); return binding; -err_free_chunk_owner: - net_devmem_dmabuf_free_chunk_owner(binding->chunk_owner); - goto err_free_freelist; -err_free_owner: - kfree(owner); +err_free_niovs: + kvfree(binding->area.niovs); err_free_freelist: kvfree(binding->freelist); kvfree(binding->tx_vec); diff --git a/net/core/devmem.h b/net/core/devmem.h index db2eb6372aee..6ed16b4b4687 100644 --- a/net/core/devmem.h +++ b/net/core/devmem.h @@ -14,9 +14,9 @@ #include struct netlink_ext_ack; -struct dmabuf_genpool_chunk_owner; struct net_devmem_dmabuf_binding { + struct net_iov_area area; struct dma_buf *dmabuf; struct dma_buf_attachment *attachment; struct sg_table *sgt; @@ -27,7 +27,6 @@ struct net_devmem_dmabuf_binding { * dereferenced. */ void *vdev; - struct dmabuf_genpool_chunk_owner *chunk_owner; /* Protect dev */ struct mutex lock; @@ -82,11 +81,6 @@ struct net_devmem_dmabuf_binding { }; #if defined(CONFIG_NET_DEVMEM) -struct dmabuf_genpool_chunk_owner { - struct net_iov_area area; - struct net_devmem_dmabuf_binding *binding; -}; - void __net_devmem_dmabuf_binding_free(struct work_struct *wq); struct net_devmem_dmabuf_binding * net_devmem_bind_dmabuf(struct net_device *dev, void *vdev, @@ -101,18 +95,11 @@ int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx, struct net_devmem_dmabuf_binding *binding, struct netlink_ext_ack *extack); -static inline struct dmabuf_genpool_chunk_owner * -net_devmem_iov_to_chunk_owner(const struct net_iov *niov) -{ - struct net_iov_area *owner = net_iov_owner(niov); - - return container_of(owner, struct dmabuf_genpool_chunk_owner, area); -} - static inline struct net_devmem_dmabuf_binding * net_devmem_iov_binding(const struct net_iov *niov) { - return net_devmem_iov_to_chunk_owner(niov)->binding; + return container_of(net_iov_owner(niov), + struct net_devmem_dmabuf_binding, area); } static inline u32 net_devmem_iov_binding_id(const struct net_iov *niov) @@ -122,11 +109,11 @@ static inline u32 net_devmem_iov_binding_id(const struct net_iov *niov) static inline unsigned long net_iov_virtual_addr(const struct net_iov *niov) { - struct dmabuf_genpool_chunk_owner *co = - net_devmem_iov_to_chunk_owner(niov); + struct net_devmem_dmabuf_binding *binding = + net_devmem_iov_binding(niov); return net_iov_owner(niov)->base_virtual + - ((unsigned long)net_iov_idx(niov) << co->binding->niov_shift); + ((unsigned long)net_iov_idx(niov) << binding->niov_shift); } static inline bool -- 2.53.0-Meta