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Message-ID: <Z__oN6HTawqLDfyG@mini-arch>
Date: Wed, 16 Apr 2025 10:26:15 -0700
From: Stanislav Fomichev <stfomichev@...il.com>
To: Mina Almasry <almasrymina@...gle.com>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-doc@...r.kernel.org, io-uring@...r.kernel.org,
kvm@...r.kernel.org, virtualization@...ts.linux.dev,
linux-kselftest@...r.kernel.org,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
Simon Horman <horms@...nel.org>,
Donald Hunter <donald.hunter@...il.com>,
Jonathan Corbet <corbet@....net>,
Andrew Lunn <andrew+netdev@...n.ch>,
Jeroen de Borst <jeroendb@...gle.com>,
Harshitha Ramamurthy <hramamurthy@...gle.com>,
Kuniyuki Iwashima <kuniyu@...zon.com>,
Willem de Bruijn <willemb@...gle.com>, Jens Axboe <axboe@...nel.dk>,
Pavel Begunkov <asml.silence@...il.com>,
David Ahern <dsahern@...nel.org>,
Neal Cardwell <ncardwell@...gle.com>,
Stefan Hajnoczi <stefanha@...hat.com>,
Stefano Garzarella <sgarzare@...hat.com>,
"Michael S. Tsirkin" <mst@...hat.com>,
Jason Wang <jasowang@...hat.com>,
Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
Eugenio Pérez <eperezma@...hat.com>,
Shuah Khan <shuah@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>,
Kaiyuan Zhang <kaiyuanz@...gle.com>
Subject: Re: [PATCH net-next v8 4/9] net: devmem: Implement TX path
On 04/15, Mina Almasry wrote:
> Augment dmabuf binding to be able to handle TX. Additional to all the RX
> binding, we also create tx_vec needed for the TX path.
>
> Provide API for sendmsg to be able to send dmabufs bound to this device:
>
> - Provide a new dmabuf_tx_cmsg which includes the dmabuf to send from.
> - MSG_ZEROCOPY with SCM_DEVMEM_DMABUF cmsg indicates send from dma-buf.
>
> Devmem is uncopyable, so piggyback off the existing MSG_ZEROCOPY
> implementation, while disabling instances where MSG_ZEROCOPY falls back
> to copying.
>
> We additionally pipe the binding down to the new
> zerocopy_fill_skb_from_devmem which fills a TX skb with net_iov netmems
> instead of the traditional page netmems.
>
> We also special case skb_frag_dma_map to return the dma-address of these
> dmabuf net_iovs instead of attempting to map pages.
>
> The TX path may release the dmabuf in a context where we cannot wait.
> This happens when the user unbinds a TX dmabuf while there are still
> references to its netmems in the TX path. In that case, the netmems will
> be put_netmem'd from a context where we can't unmap the dmabuf, Resolve
> this by making __net_devmem_dmabuf_binding_free schedule_work'd.
>
> Based on work by Stanislav Fomichev <sdf@...ichev.me>. A lot of the meat
> of the implementation came from devmem TCP RFC v1[1], which included the
> TX path, but Stan did all the rebasing on top of netmem/net_iov.
>
> Cc: Stanislav Fomichev <sdf@...ichev.me>
> Signed-off-by: Kaiyuan Zhang <kaiyuanz@...gle.com>
> Signed-off-by: Mina Almasry <almasrymina@...gle.com>
> Acked-by: Stanislav Fomichev <sdf@...ichev.me>
>
> ---
>
> v8:
> - move adding the binding to the net_devmem_dmabuf_bindings after it's
> been fully initialized to eliminate potential for races with send path
> (Stan).
> - Use net_devmem_get_by_index_lock instead of rtnl_locking
>
> v6:
> - Retain behavior that MSG_FASTOPEN succeeds even if cmsg is invalid
> (Paolo).
> - Rework the freeing of tx_vec slightly to improve readability. Now it
> has its own err label (Paolo).
> - Squash making unbinding scheduled work (Paolo).
> - Add comment to clarify that net_iovs stuck in the transmit path hold
> a ref on the underlying dmabuf binding (David).
> - Fix the comment on how binding refcounting works on RX (the comment
> was not matching the existing code behavior).
>
> v5:
> - Return -EFAULT from zerocopy_fill_skb_from_devmem (Stan)
> - don't null check before kvfree (stan).
>
> v4:
> - Remove dmabuf_tx_cmsg definition and just use __u32 for the dma-buf id
> (Willem).
> - Check that iov_iter_type() is ITER_IOVEC in
> zerocopy_fill_skb_from_iter() (Pavel).
> - Fix binding->tx_vec not being freed on error paths (Paolo).
> - Make devmem patch mutually exclusive with msg->ubuf_info path (Pavel).
> - Check that MSG_ZEROCOPY and SOCK_ZEROCOPY are provided when
> sockc.dmabuf_id is provided.
> - Don't mm_account_pinned_pages() on devmem TX (Pavel).
>
> v3:
> - Use kvmalloc_array instead of kcalloc (Stan).
> - Fix unreachable code warning (Simon).
>
> v2:
> - Remove dmabuf_offset from the dmabuf cmsg.
> - Update zerocopy_fill_skb_from_devmem to interpret the
> iov_base/iter_iov_addr as the offset into the dmabuf to send from
> (Stan).
> - Remove the confusing binding->tx_iter which is not needed if we
> interpret the iov_base/iter_iov_addr as offset into the dmabuf (Stan).
> - Remove check for binding->sgt and binding->sgt->nents in dmabuf
> binding.
> - Simplify the calculation of binding->tx_vec.
> - Check in net_devmem_get_binding that the binding we're returning
> has ifindex matching the sending socket (Willem).
> ---
> include/linux/skbuff.h | 17 +++-
> include/net/sock.h | 1 +
> net/core/datagram.c | 48 ++++++++-
> net/core/devmem.c | 127 ++++++++++++++++++++----
> net/core/devmem.h | 61 ++++++++++--
> net/core/netdev-genl.c | 62 +++++++++++-
> net/core/skbuff.c | 18 ++--
> net/core/sock.c | 6 ++
> net/ipv4/ip_output.c | 3 +-
> net/ipv4/tcp.c | 50 ++++++++--
> net/ipv6/ip6_output.c | 3 +-
> net/vmw_vsock/virtio_transport_common.c | 5 +-
> 12 files changed, 338 insertions(+), 63 deletions(-)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index f1381aff0f89..10dc0a439108 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -1710,13 +1710,16 @@ static inline void skb_set_end_offset(struct sk_buff *skb, unsigned int offset)
> extern const struct ubuf_info_ops msg_zerocopy_ubuf_ops;
>
> struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
> - struct ubuf_info *uarg);
> + struct ubuf_info *uarg, bool devmem);
>
> void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref);
>
> +struct net_devmem_dmabuf_binding;
> +
> int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
> struct sk_buff *skb, struct iov_iter *from,
> - size_t length);
> + size_t length,
> + struct net_devmem_dmabuf_binding *binding);
>
> int zerocopy_fill_skb_from_iter(struct sk_buff *skb,
> struct iov_iter *from, size_t length);
> @@ -1724,12 +1727,14 @@ int zerocopy_fill_skb_from_iter(struct sk_buff *skb,
> static inline int skb_zerocopy_iter_dgram(struct sk_buff *skb,
> struct msghdr *msg, int len)
> {
> - return __zerocopy_sg_from_iter(msg, skb->sk, skb, &msg->msg_iter, len);
> + return __zerocopy_sg_from_iter(msg, skb->sk, skb, &msg->msg_iter, len,
> + NULL);
> }
>
> int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
> struct msghdr *msg, int len,
> - struct ubuf_info *uarg);
> + struct ubuf_info *uarg,
> + struct net_devmem_dmabuf_binding *binding);
>
> /* Internal */
> #define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
> @@ -3700,6 +3705,10 @@ static inline dma_addr_t __skb_frag_dma_map(struct device *dev,
> size_t offset, size_t size,
> enum dma_data_direction dir)
> {
> + if (skb_frag_is_net_iov(frag)) {
> + return netmem_to_net_iov(frag->netmem)->dma_addr + offset +
> + frag->offset;
> + }
> return dma_map_page(dev, skb_frag_page(frag),
> skb_frag_off(frag) + offset, size, dir);
> }
> diff --git a/include/net/sock.h b/include/net/sock.h
> index bb4d6189292f..5cb10cc0ca6e 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -1851,6 +1851,7 @@ struct sockcm_cookie {
> u32 tsflags;
> u32 ts_opt_id;
> u32 priority;
> + u32 dmabuf_id;
> };
>
> static inline void sockcm_init(struct sockcm_cookie *sockc,
> diff --git a/net/core/datagram.c b/net/core/datagram.c
> index f0634f0cb834..042a7dceb85a 100644
> --- a/net/core/datagram.c
> +++ b/net/core/datagram.c
> @@ -63,6 +63,8 @@
> #include <net/busy_poll.h>
> #include <crypto/hash.h>
>
> +#include "devmem.h"
> +
> /*
> * Is a socket 'connection oriented' ?
> */
> @@ -691,9 +693,49 @@ int zerocopy_fill_skb_from_iter(struct sk_buff *skb,
> return 0;
> }
>
> +static int
> +zerocopy_fill_skb_from_devmem(struct sk_buff *skb, struct iov_iter *from,
> + int length,
> + struct net_devmem_dmabuf_binding *binding)
> +{
> + int i = skb_shinfo(skb)->nr_frags;
> + size_t virt_addr, size, off;
> + struct net_iov *niov;
> +
> + /* Devmem filling works by taking an IOVEC from the user where the
> + * iov_addrs are interpreted as an offset in bytes into the dma-buf to
> + * send from. We do not support other iter types.
> + */
> + if (iov_iter_type(from) != ITER_IOVEC)
> + return -EFAULT;
> +
> + while (length && iov_iter_count(from)) {
> + if (i == MAX_SKB_FRAGS)
> + return -EMSGSIZE;
> +
> + virt_addr = (size_t)iter_iov_addr(from);
> + niov = net_devmem_get_niov_at(binding, virt_addr, &off, &size);
> + if (!niov)
> + return -EFAULT;
> +
> + size = min_t(size_t, size, length);
> + size = min_t(size_t, size, iter_iov_len(from));
> +
> + get_netmem(net_iov_to_netmem(niov));
> + skb_add_rx_frag_netmem(skb, i, net_iov_to_netmem(niov), off,
> + size, PAGE_SIZE);
> + iov_iter_advance(from, size);
> + length -= size;
> + i++;
> + }
> +
> + return 0;
> +}
> +
> int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
> struct sk_buff *skb, struct iov_iter *from,
> - size_t length)
> + size_t length,
> + struct net_devmem_dmabuf_binding *binding)
> {
> unsigned long orig_size = skb->truesize;
> unsigned long truesize;
> @@ -701,6 +743,8 @@ int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
>
> if (msg && msg->msg_ubuf && msg->sg_from_iter)
> ret = msg->sg_from_iter(skb, from, length);
> + else if (unlikely(binding))
> + ret = zerocopy_fill_skb_from_devmem(skb, from, length, binding);
> else
> ret = zerocopy_fill_skb_from_iter(skb, from, length);
>
> @@ -734,7 +778,7 @@ int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *from)
> if (skb_copy_datagram_from_iter(skb, 0, from, copy))
> return -EFAULT;
>
> - return __zerocopy_sg_from_iter(NULL, NULL, skb, from, ~0U);
> + return __zerocopy_sg_from_iter(NULL, NULL, skb, from, ~0U, NULL);
> }
> EXPORT_SYMBOL(zerocopy_sg_from_iter);
>
> diff --git a/net/core/devmem.c b/net/core/devmem.c
> index dca2ff7cf692..9599a82990e6 100644
> --- a/net/core/devmem.c
> +++ b/net/core/devmem.c
> @@ -16,6 +16,7 @@
> #include <net/netdev_rx_queue.h>
> #include <net/page_pool/helpers.h>
> #include <net/page_pool/memory_provider.h>
> +#include <net/sock.h>
> #include <trace/events/page_pool.h>
>
> #include "devmem.h"
> @@ -52,8 +53,10 @@ static dma_addr_t net_devmem_get_dma_addr(const struct net_iov *niov)
> ((dma_addr_t)net_iov_idx(niov) << PAGE_SHIFT);
> }
>
> -void __net_devmem_dmabuf_binding_free(struct net_devmem_dmabuf_binding *binding)
> +void __net_devmem_dmabuf_binding_free(struct work_struct *wq)
> {
> + struct net_devmem_dmabuf_binding *binding = container_of(wq, typeof(*binding), unbind_w);
> +
> size_t size, avail;
>
> gen_pool_for_each_chunk(binding->chunk_pool,
> @@ -71,8 +74,10 @@ void __net_devmem_dmabuf_binding_free(struct net_devmem_dmabuf_binding *binding)
> dma_buf_detach(binding->dmabuf, binding->attachment);
> dma_buf_put(binding->dmabuf);
> xa_destroy(&binding->bound_rxqs);
> + kvfree(binding->tx_vec);
> kfree(binding);
> }
> +EXPORT_SYMBOL(__net_devmem_dmabuf_binding_free);
>
> struct net_iov *
> net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding)
> @@ -117,6 +122,13 @@ void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding)
> unsigned long xa_idx;
> unsigned int rxq_idx;
>
> + xa_erase(&net_devmem_dmabuf_bindings, binding->id);
> +
> + /* Ensure no tx net_devmem_lookup_dmabuf() are in flight after the
> + * erase.
> + */
> + synchronize_net();
> +
> if (binding->list.next)
> list_del(&binding->list);
>
> @@ -131,8 +143,6 @@ void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding)
> __net_mp_close_rxq(binding->dev, rxq_idx, &mp_params);
> }
>
> - xa_erase(&net_devmem_dmabuf_bindings, binding->id);
> -
> net_devmem_dmabuf_binding_put(binding);
> }
>
> @@ -166,8 +176,9 @@ int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
> }
>
> struct net_devmem_dmabuf_binding *
> -net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
> - struct netlink_ext_ack *extack)
> +net_devmem_bind_dmabuf(struct net_device *dev,
> + enum dma_data_direction direction,
> + unsigned int dmabuf_fd, struct netlink_ext_ack *extack)
> {
> struct net_devmem_dmabuf_binding *binding;
> static u32 id_alloc_next;
> @@ -189,43 +200,44 @@ net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
> }
>
> binding->dev = dev;
> -
> - err = xa_alloc_cyclic(&net_devmem_dmabuf_bindings, &binding->id,
> - binding, xa_limit_32b, &id_alloc_next,
> - GFP_KERNEL);
> - if (err < 0)
> - goto err_free_binding;
> -
> xa_init_flags(&binding->bound_rxqs, XA_FLAGS_ALLOC);
> -
> refcount_set(&binding->ref, 1);
> -
> binding->dmabuf = dmabuf;
>
> binding->attachment = dma_buf_attach(binding->dmabuf, dev->dev.parent);
> if (IS_ERR(binding->attachment)) {
> err = PTR_ERR(binding->attachment);
> NL_SET_ERR_MSG(extack, "Failed to bind dmabuf to device");
> - goto err_free_id;
> + goto err_free_binding;
> }
>
> binding->sgt = dma_buf_map_attachment_unlocked(binding->attachment,
> - DMA_FROM_DEVICE);
> + direction);
> if (IS_ERR(binding->sgt)) {
> err = PTR_ERR(binding->sgt);
> NL_SET_ERR_MSG(extack, "Failed to map dmabuf attachment");
> goto err_detach;
> }
>
> + if (direction == DMA_TO_DEVICE) {
> + binding->tx_vec = kvmalloc_array(dmabuf->size / PAGE_SIZE,
> + sizeof(struct net_iov *),
> + GFP_KERNEL);
> + if (!binding->tx_vec) {
> + err = -ENOMEM;
> + goto err_unmap;
> + }
> + }
> +
> /* For simplicity we expect to make PAGE_SIZE allocations, but the
> * binding can be much more flexible than that. We may be able to
> * allocate MTU sized chunks here. Leave that for future work...
> */
> - binding->chunk_pool =
> - gen_pool_create(PAGE_SHIFT, dev_to_node(&dev->dev));
> + binding->chunk_pool = gen_pool_create(PAGE_SHIFT,
> + dev_to_node(&dev->dev));
> if (!binding->chunk_pool) {
> err = -ENOMEM;
> - goto err_unmap;
> + goto err_tx_vec;
> }
>
> virtual = 0;
> @@ -270,24 +282,35 @@ net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
> niov->owner = &owner->area;
> page_pool_set_dma_addr_netmem(net_iov_to_netmem(niov),
> net_devmem_get_dma_addr(niov));
> + if (direction == DMA_TO_DEVICE)
> + binding->tx_vec[owner->area.base_virtual / PAGE_SIZE + i] = niov;
> }
>
> virtual += len;
> }
>
> + err = xa_alloc_cyclic(&net_devmem_dmabuf_bindings, &binding->id,
> + binding, xa_limit_32b, &id_alloc_next,
> + GFP_KERNEL);
> + if (err < 0)
> + goto err_free_id;
> +
> +
> return binding;
>
> +err_free_id:
> + xa_erase(&net_devmem_dmabuf_bindings, binding->id);
> err_free_chunks:
> gen_pool_for_each_chunk(binding->chunk_pool,
> net_devmem_dmabuf_free_chunk_owner, NULL);
> gen_pool_destroy(binding->chunk_pool);
> +err_tx_vec:
> + kvfree(binding->tx_vec);
> err_unmap:
> dma_buf_unmap_attachment_unlocked(binding->attachment, binding->sgt,
> DMA_FROM_DEVICE);
> err_detach:
> dma_buf_detach(dmabuf, binding->attachment);
> -err_free_id:
> - xa_erase(&net_devmem_dmabuf_bindings, binding->id);
> err_free_binding:
> kfree(binding);
> err_put_dmabuf:
> @@ -295,6 +318,21 @@ net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
> return ERR_PTR(err);
> }
>
> +struct net_devmem_dmabuf_binding *net_devmem_lookup_dmabuf(u32 id)
> +{
> + struct net_devmem_dmabuf_binding *binding;
> +
> + rcu_read_lock();
> + binding = xa_load(&net_devmem_dmabuf_bindings, id);
> + if (binding) {
> + if (!net_devmem_dmabuf_binding_get(binding))
> + binding = NULL;
> + }
> + rcu_read_unlock();
> +
> + return binding;
> +}
> +
> void net_devmem_get_net_iov(struct net_iov *niov)
> {
> net_devmem_dmabuf_binding_get(net_devmem_iov_binding(niov));
> @@ -305,6 +343,53 @@ void net_devmem_put_net_iov(struct net_iov *niov)
> net_devmem_dmabuf_binding_put(net_devmem_iov_binding(niov));
> }
>
> +struct net_devmem_dmabuf_binding *net_devmem_get_binding(struct sock *sk,
> + unsigned int dmabuf_id)
> +{
> + struct net_devmem_dmabuf_binding *binding;
> + struct dst_entry *dst = __sk_dst_get(sk);
> + int err = 0;
> +
> + binding = net_devmem_lookup_dmabuf(dmabuf_id);
> + if (!binding || !binding->tx_vec) {
> + err = -EINVAL;
> + goto out_err;
> + }
> +
> + /* The dma-addrs in this binding are only reachable to the corresponding
> + * net_device.
> + */
> + if (!dst || !dst->dev || dst->dev->ifindex != binding->dev->ifindex) {
> + err = -ENODEV;
> + goto out_err;
> + }
> +
> + return binding;
> +
> +out_err:
> + if (binding)
> + net_devmem_dmabuf_binding_put(binding);
> +
> + return ERR_PTR(err);
> +}
> +
> +struct net_iov *
> +net_devmem_get_niov_at(struct net_devmem_dmabuf_binding *binding,
> + size_t virt_addr, size_t *off, size_t *size)
> +{
> + size_t idx;
> +
> + if (virt_addr >= binding->dmabuf->size)
> + return NULL;
> +
> + idx = virt_addr / PAGE_SIZE;
> +
> + *off = virt_addr % PAGE_SIZE;
> + *size = PAGE_SIZE - *off;
> +
> + return binding->tx_vec[idx];
> +}
> +
> /*** "Dmabuf devmem memory provider" ***/
>
> int mp_dmabuf_devmem_init(struct page_pool *pool)
> diff --git a/net/core/devmem.h b/net/core/devmem.h
> index 946f2e015746..67168aae5e5b 100644
> --- a/net/core/devmem.h
> +++ b/net/core/devmem.h
> @@ -23,8 +23,9 @@ struct net_devmem_dmabuf_binding {
>
> /* The user holds a ref (via the netlink API) for as long as they want
> * the binding to remain alive. Each page pool using this binding holds
> - * a ref to keep the binding alive. Each allocated net_iov holds a
> - * ref.
> + * a ref to keep the binding alive. The page_pool does not release the
> + * ref until all the net_iovs allocated from this binding are released
> + * back to the page_pool.
> *
> * The binding undos itself and unmaps the underlying dmabuf once all
> * those refs are dropped and the binding is no longer desired or in
> @@ -32,7 +33,10 @@ struct net_devmem_dmabuf_binding {
> *
> * net_devmem_get_net_iov() on dmabuf net_iovs will increment this
> * reference, making sure that the binding remains alive until all the
> - * net_iovs are no longer used.
> + * net_iovs are no longer used. net_iovs allocated from this binding
> + * that are stuck in the TX path for any reason (such as awaiting
> + * retransmits) hold a reference to the binding until the skb holding
> + * them is freed.
> */
> refcount_t ref;
>
> @@ -48,6 +52,14 @@ struct net_devmem_dmabuf_binding {
> * active.
> */
> u32 id;
> +
> + /* Array of net_iov pointers for this binding, sorted by virtual
> + * address. This array is convenient to map the virtual addresses to
> + * net_iovs in the TX path.
> + */
> + struct net_iov **tx_vec;
> +
> + struct work_struct unbind_w;
> };
>
> #if defined(CONFIG_NET_DEVMEM)
> @@ -64,14 +76,17 @@ struct dmabuf_genpool_chunk_owner {
> dma_addr_t base_dma_addr;
> };
>
> -void __net_devmem_dmabuf_binding_free(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, unsigned int dmabuf_fd,
> - struct netlink_ext_ack *extack);
> +net_devmem_bind_dmabuf(struct net_device *dev,
> + enum dma_data_direction direction,
> + unsigned int dmabuf_fd, struct netlink_ext_ack *extack);
> +struct net_devmem_dmabuf_binding *net_devmem_lookup_dmabuf(u32 id);
> void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding);
> 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);
> +void net_devmem_bind_tx_release(struct sock *sk);
>
> static inline struct dmabuf_genpool_chunk_owner *
> net_devmem_iov_to_chunk_owner(const struct net_iov *niov)
> @@ -100,10 +115,10 @@ static inline unsigned long net_iov_virtual_addr(const struct net_iov *niov)
> ((unsigned long)net_iov_idx(niov) << PAGE_SHIFT);
> }
>
> -static inline void
> +static inline bool
> net_devmem_dmabuf_binding_get(struct net_devmem_dmabuf_binding *binding)
> {
> - refcount_inc(&binding->ref);
> + return refcount_inc_not_zero(&binding->ref);
> }
>
> static inline void
> @@ -112,7 +127,8 @@ net_devmem_dmabuf_binding_put(struct net_devmem_dmabuf_binding *binding)
> if (!refcount_dec_and_test(&binding->ref))
> return;
>
> - __net_devmem_dmabuf_binding_free(binding);
> + INIT_WORK(&binding->unbind_w, __net_devmem_dmabuf_binding_free);
> + schedule_work(&binding->unbind_w);
> }
>
> void net_devmem_get_net_iov(struct net_iov *niov);
> @@ -123,6 +139,11 @@ net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding);
> void net_devmem_free_dmabuf(struct net_iov *ppiov);
>
> bool net_is_devmem_iov(struct net_iov *niov);
> +struct net_devmem_dmabuf_binding *
> +net_devmem_get_binding(struct sock *sk, unsigned int dmabuf_id);
> +struct net_iov *
> +net_devmem_get_niov_at(struct net_devmem_dmabuf_binding *binding, size_t addr,
> + size_t *off, size_t *size);
>
> #else
> struct net_devmem_dmabuf_binding;
> @@ -140,18 +161,23 @@ static inline void net_devmem_put_net_iov(struct net_iov *niov)
> {
> }
>
> -static inline void
> -__net_devmem_dmabuf_binding_free(struct net_devmem_dmabuf_binding *binding)
> +static inline void __net_devmem_dmabuf_binding_free(struct work_struct *wq)
> {
> }
>
> static inline struct net_devmem_dmabuf_binding *
> net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
> + enum dma_data_direction direction,
> struct netlink_ext_ack *extack)
> {
> return ERR_PTR(-EOPNOTSUPP);
> }
>
> +static inline struct net_devmem_dmabuf_binding *net_devmem_lookup_dmabuf(u32 id)
> +{
> + return NULL;
> +}
> +
> static inline void
> net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding)
> {
> @@ -190,6 +216,19 @@ static inline bool net_is_devmem_iov(struct net_iov *niov)
> {
> return false;
> }
> +
> +static inline struct net_devmem_dmabuf_binding *
> +net_devmem_get_binding(struct sock *sk, unsigned int dmabuf_id)
> +{
> + return ERR_PTR(-EOPNOTSUPP);
> +}
> +
> +static inline struct net_iov *
> +net_devmem_get_niov_at(struct net_devmem_dmabuf_binding *binding, size_t addr,
> + size_t *off, size_t *size)
> +{
> + return NULL;
> +}
> #endif
>
> #endif /* _NET_DEVMEM_H */
> diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
> index 5e42f800dfcf..56502923f885 100644
> --- a/net/core/netdev-genl.c
> +++ b/net/core/netdev-genl.c
> @@ -873,7 +873,8 @@ int netdev_nl_bind_rx_doit(struct sk_buff *skb, struct genl_info *info)
> goto err_unlock;
> }
>
> - binding = net_devmem_bind_dmabuf(netdev, dmabuf_fd, info->extack);
> + binding = net_devmem_bind_dmabuf(netdev, DMA_FROM_DEVICE, dmabuf_fd,
> + info->extack);
> if (IS_ERR(binding)) {
> err = PTR_ERR(binding);
> goto err_unlock;
> @@ -934,10 +935,65 @@ int netdev_nl_bind_rx_doit(struct sk_buff *skb, struct genl_info *info)
> return err;
> }
>
> -/* stub */
> int netdev_nl_bind_tx_doit(struct sk_buff *skb, struct genl_info *info)
> {
> - return 0;
> + struct net_devmem_dmabuf_binding *binding;
> + struct list_head *sock_binding_list;
> + struct net_device *netdev;
> + u32 ifindex, dmabuf_fd;
> + struct sk_buff *rsp;
> + int err = 0;
> + void *hdr;
> +
> + if (GENL_REQ_ATTR_CHECK(info, NETDEV_A_DEV_IFINDEX) ||
> + GENL_REQ_ATTR_CHECK(info, NETDEV_A_DMABUF_FD))
> + return -EINVAL;
> +
> + ifindex = nla_get_u32(info->attrs[NETDEV_A_DEV_IFINDEX]);
> + dmabuf_fd = nla_get_u32(info->attrs[NETDEV_A_DMABUF_FD]);
> +
> + sock_binding_list = genl_sk_priv_get(&netdev_nl_family,
> + NETLINK_CB(skb).sk);
> + if (IS_ERR(sock_binding_list))
> + return PTR_ERR(sock_binding_list);
> +
> + rsp = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
> + if (!rsp)
> + return -ENOMEM;
> +
> + hdr = genlmsg_iput(rsp, info);
> + if (!hdr) {
> + err = -EMSGSIZE;
> + goto err_genlmsg_free;
> + }
> +
> + netdev = netdev_get_by_index_lock(genl_info_net(info), ifindex);
> + if (!netdev || !netif_device_present(netdev)) {
> + err = -ENODEV;
> + goto err_unlock;
> + }
> +
> + binding = net_devmem_bind_dmabuf(netdev, DMA_TO_DEVICE, dmabuf_fd,
> + info->extack);
> + if (IS_ERR(binding)) {
> + err = PTR_ERR(binding);
> + goto err_unlock;
> + }
> +
> + list_add(&binding->list, sock_binding_list);
> +
> + nla_put_u32(rsp, NETDEV_A_DMABUF_ID, binding->id);
> + genlmsg_end(rsp, hdr);
> +
> + netdev_unlock(netdev);
> +
> + return genlmsg_reply(rsp, info);
> +
> +err_unlock:
> + netdev_unlock(netdev);
> +err_genlmsg_free:
> + nlmsg_free(rsp);
> + return err;
> }
The above needs to be converted to netdev_nl_sock? Untested:
diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index 33cf5b21aeef..1c6b1dfa5742 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -938,7 +938,7 @@ int netdev_nl_bind_rx_doit(struct sk_buff *skb, struct genl_info *info)
int netdev_nl_bind_tx_doit(struct sk_buff *skb, struct genl_info *info)
{
struct net_devmem_dmabuf_binding *binding;
- struct list_head *sock_binding_list;
+ struct netdev_nl_sock *priv;
struct net_device *netdev;
u32 ifindex, dmabuf_fd;
struct sk_buff *rsp;
@@ -952,10 +952,9 @@ int netdev_nl_bind_tx_doit(struct sk_buff *skb, struct genl_info *info)
ifindex = nla_get_u32(info->attrs[NETDEV_A_DEV_IFINDEX]);
dmabuf_fd = nla_get_u32(info->attrs[NETDEV_A_DMABUF_FD]);
- sock_binding_list = genl_sk_priv_get(&netdev_nl_family,
- NETLINK_CB(skb).sk);
- if (IS_ERR(sock_binding_list))
- return PTR_ERR(sock_binding_list);
+ priv = genl_sk_priv_get(&netdev_nl_family, NETLINK_CB(skb).sk);
+ if (IS_ERR(priv))
+ return PTR_ERR(priv);
rsp = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
if (!rsp)
@@ -967,10 +966,12 @@ int netdev_nl_bind_tx_doit(struct sk_buff *skb, struct genl_info *info)
goto err_genlmsg_free;
}
+ mutex_lock(&priv->lock);
+
netdev = netdev_get_by_index_lock(genl_info_net(info), ifindex);
if (!netdev || !netif_device_present(netdev)) {
err = -ENODEV;
- goto err_unlock;
+ goto err_unlock_sock;
}
#if 0
@@ -989,17 +990,21 @@ int netdev_nl_bind_tx_doit(struct sk_buff *skb, struct genl_info *info)
goto err_unlock;
}
- list_add(&binding->list, sock_binding_list);
+ list_add(&binding->list, &priv->bindings);
nla_put_u32(rsp, NETDEV_A_DMABUF_ID, binding->id);
genlmsg_end(rsp, hdr);
netdev_unlock(netdev);
+ mutex_unlock(&priv->lock);
+
return genlmsg_reply(rsp, info);
err_unlock:
netdev_unlock(netdev);
+err_unlock_sock:
+ mutex_unlock(&priv->lock);
err_genlmsg_free:
nlmsg_free(rsp);
return err;
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