On 2024/3/5 10:01, Mina Almasry wrote:
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The netdev_dmabuf_binding struct is refcounted, and releases its resources only when all the refs are released.
Signed-off-by: Willem de Bruijn willemb@google.com Signed-off-by: Kaiyuan Zhang kaiyuanz@google.com Signed-off-by: Mina Almasry almasrymina@google.com
RFC v6:
- Validate rx queue index
- Refactor new functions into devmem.c (Pavel)
It seems odd that the functions or stucts in a file called devmem.c are named after 'dmabuf' instead of 'devmem'.
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diff --git a/include/net/netmem.h b/include/net/netmem.h index d8b810245c1d..72e932a1a948 100644 --- a/include/net/netmem.h +++ b/include/net/netmem.h @@ -8,6 +8,16 @@ #ifndef _NET_NETMEM_H #define _NET_NETMEM_H +#include <net/devmem.h>
+/* net_iov */
+struct net_iov {
- struct dmabuf_genpool_chunk_owner *owner;
+};
+/* netmem */
/**
- typedef netmem_ref - a nonexistent type marking a reference to generic
- network memory.
diff --git a/net/core/Makefile b/net/core/Makefile index 821aec06abf1..592f955c1241 100644 --- a/net/core/Makefile +++ b/net/core/Makefile @@ -13,7 +13,7 @@ obj-y += dev.o dev_addr_lists.o dst.o netevent.o \ neighbour.o rtnetlink.o utils.o link_watch.o filter.o \ sock_diag.o dev_ioctl.o tso.o sock_reuseport.o \ fib_notifier.o xdp.o flow_offload.o gro.o \
netdev-genl.o netdev-genl-gen.o gso.o
netdev-genl.o netdev-genl-gen.o gso.o devmem.oobj-$(CONFIG_NETDEV_ADDR_LIST_TEST) += dev_addr_lists_test.o diff --git a/net/core/dev.c b/net/core/dev.c index fe054cbd41e9..bbea1b252529 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -155,6 +155,9 @@ #include <net/netdev_rx_queue.h> #include <net/page_pool/types.h> #include <net/page_pool/helpers.h> +#include <linux/genalloc.h> +#include <linux/dma-buf.h> +#include <net/devmem.h> #include "dev.h" #include "net-sysfs.h" diff --git a/net/core/devmem.c b/net/core/devmem.c new file mode 100644 index 000000000000..779ad990971e --- /dev/null +++ b/net/core/devmem.c @@ -0,0 +1,293 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/*
Devmem TCP
Authors: Mina Almasry <almasrymina@google.com>
Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Kaiyuan Zhang <kaiyuanz@google.com- */
+#include <linux/types.h> +#include <linux/mm.h> +#include <linux/netdevice.h> +#include <trace/events/page_pool.h> +#include <net/netdev_rx_queue.h> +#include <net/page_pool/types.h> +#include <net/page_pool/helpers.h> +#include <linux/genalloc.h> +#include <linux/dma-buf.h> +#include <net/devmem.h>
+/* Device memory support */
+#ifdef CONFIG_DMA_SHARED_BUFFER
I still think it is worth adding its own config for devmem or dma-buf for networking, thinking about the embeded system.
+static void netdev_dmabuf_free_chunk_owner(struct gen_pool *genpool,
struct gen_pool_chunk *chunk,void *not_used)
It seems odd to still keep the netdev_ prefix as it is not really related to netdev, perhaps use 'net_' or something better.
+{
- struct dmabuf_genpool_chunk_owner *owner = chunk->owner;
- kvfree(owner->niovs);
- kfree(owner);
+}
+void __netdev_dmabuf_binding_free(struct netdev_dmabuf_binding *binding) +{
- size_t size, avail;
- gen_pool_for_each_chunk(binding->chunk_pool,
netdev_dmabuf_free_chunk_owner, NULL);- size = gen_pool_size(binding->chunk_pool);
- avail = gen_pool_avail(binding->chunk_pool);
- if (!WARN(size != avail, "can't destroy genpool. size=%lu, avail=%lu",
size, avail))gen_pool_destroy(binding->chunk_pool);- dma_buf_unmap_attachment(binding->attachment, binding->sgt,
DMA_BIDIRECTIONAL);
For now DMA_FROM_DEVICE seems enough as tx is not supported yet.
- dma_buf_detach(binding->dmabuf, binding->attachment);
- dma_buf_put(binding->dmabuf);
- xa_destroy(&binding->bound_rxq_list);
- kfree(binding);
+}
+static int netdev_restart_rx_queue(struct net_device *dev, int rxq_idx) +{
- void *new_mem;
- void *old_mem;
- int err;
- if (!dev || !dev->netdev_ops)
return -EINVAL;- if (!dev->netdev_ops->ndo_queue_stop ||
!dev->netdev_ops->ndo_queue_mem_free ||!dev->netdev_ops->ndo_queue_mem_alloc ||!dev->netdev_ops->ndo_queue_start)return -EOPNOTSUPP;- new_mem = dev->netdev_ops->ndo_queue_mem_alloc(dev, rxq_idx);
- if (!new_mem)
return -ENOMEM;- err = dev->netdev_ops->ndo_queue_stop(dev, rxq_idx, &old_mem);
- if (err)
goto err_free_new_mem;- err = dev->netdev_ops->ndo_queue_start(dev, rxq_idx, new_mem);
- if (err)
goto err_start_queue;- dev->netdev_ops->ndo_queue_mem_free(dev, old_mem);
- return 0;
+err_start_queue:
- dev->netdev_ops->ndo_queue_start(dev, rxq_idx, old_mem);
It might worth mentioning why queue start with old_mem will always success here as the return value seems to be ignored here.
+err_free_new_mem:
- dev->netdev_ops->ndo_queue_mem_free(dev, new_mem);
- return err;
+}
+/* Protected by rtnl_lock() */ +static DEFINE_XARRAY_FLAGS(netdev_dmabuf_bindings, XA_FLAGS_ALLOC1);
+void netdev_unbind_dmabuf(struct netdev_dmabuf_binding *binding) +{
- struct netdev_rx_queue *rxq;
- unsigned long xa_idx;
- unsigned int rxq_idx;
- if (!binding)
return;- if (binding->list.next)
list_del(&binding->list);
The above does not seems to be a good pattern to delete a entry, is there any reason having a checking before the list_del()? seems like defensive programming?
- xa_for_each(&binding->bound_rxq_list, xa_idx, rxq) {
if (rxq->binding == binding) {
It seems like defensive programming here too?
/* We hold the rtnl_lock while binding/unbinding* dma-buf, so we can't race with another thread that* is also modifying this value. However, the driver* may read this config while it's creating its* rx-queues. WRITE_ONCE() here to match the* READ_ONCE() in the driver.*/WRITE_ONCE(rxq->binding, NULL);rxq_idx = get_netdev_rx_queue_index(rxq);netdev_restart_rx_queue(binding->dev, rxq_idx);}- }
- xa_erase(&netdev_dmabuf_bindings, binding->id);
- netdev_dmabuf_binding_put(binding);
+}