net: generalise net_iov chunk owners

Currently net_iov stores a pointer to struct dmabuf_genpool_chunk_owner,
which serves as a useful abstraction to share data and provide a
context. However, it's too devmem specific, and we want to reuse it for
other memory providers, and for that we need to decouple net_iov from
devmem. Make net_iov to point to a new base structure called
net_iov_area, which dmabuf_genpool_chunk_owner extends.

Reviewed-by: Mina Almasry <almasrymina@google.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: David Wei <dw@davidwei.uk>
Link: https://patch.msgid.link/20250204215622.695511-4-dw@davidwei.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/netmem.h b/include/net/netmem.h
index 1b58faa4f20f9cbea4bbc9b0ba38484f94f8a322..c61d5b21e7b42a6974b45f19f3da225616db7321 100644 (file)
--- a/include/net/netmem.h
+++ b/include/net/netmem.h
@@ -24,11 +24,20 @@ struct net_iov {
        unsigned long __unused_padding;
        unsigned long pp_magic;
        struct page_pool *pp;
-       struct dmabuf_genpool_chunk_owner *owner;
+       struct net_iov_area *owner;
        unsigned long dma_addr;
        atomic_long_t pp_ref_count;
 };
 
+struct net_iov_area {
+       /* Array of net_iovs for this area. */
+       struct net_iov *niovs;
+       size_t num_niovs;
+
+       /* Offset into the dma-buf where this chunk starts.  */
+       unsigned long base_virtual;
+};
+
 /* These fields in struct page are used by the page_pool and net stack:
  *
  *        struct {
@@ -54,6 +63,16 @@ NET_IOV_ASSERT_OFFSET(dma_addr, dma_addr);
 NET_IOV_ASSERT_OFFSET(pp_ref_count, pp_ref_count);
 #undef NET_IOV_ASSERT_OFFSET
 
+static inline struct net_iov_area *net_iov_owner(const struct net_iov *niov)
+{
+       return niov->owner;
+}
+
+static inline unsigned int net_iov_idx(const struct net_iov *niov)
+{
+       return niov - net_iov_owner(niov)->niovs;
+}
+
 /* netmem */
 
 /**

diff --git a/net/core/devmem.c b/net/core/devmem.c
index 66cd1ab9224fb86951c55c9acd26e4c8f41ddc47..fb0dddcb4e602b4cadefb9621781d5629fa5292e 100644 (file)
--- a/net/core/devmem.c
+++ b/net/core/devmem.c
@@ -33,14 +33,15 @@ static void net_devmem_dmabuf_free_chunk_owner(struct gen_pool *genpool,
 {
        struct dmabuf_genpool_chunk_owner *owner = chunk->owner;
 
-       kvfree(owner->niovs);
+       kvfree(owner->area.niovs);
        kfree(owner);
 }
 
 static dma_addr_t net_devmem_get_dma_addr(const struct net_iov *niov)
 {
-       struct dmabuf_genpool_chunk_owner *owner = net_iov_owner(niov);
+       struct dmabuf_genpool_chunk_owner *owner;
 
+       owner = net_devmem_iov_to_chunk_owner(niov);
        return owner->base_dma_addr +
               ((dma_addr_t)net_iov_idx(niov) << PAGE_SHIFT);
 }
@@ -83,7 +84,7 @@ net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding)
 
        offset = dma_addr - owner->base_dma_addr;
        index = offset / PAGE_SIZE;
-       niov = &owner->niovs[index];
+       niov = &owner->area.niovs[index];
 
        niov->pp_magic = 0;
        niov->pp = NULL;
@@ -261,9 +262,9 @@ net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
                        goto err_free_chunks;
                }
 
-               owner->base_virtual = virtual;
+               owner->area.base_virtual = virtual;
                owner->base_dma_addr = dma_addr;
-               owner->num_niovs = len / PAGE_SIZE;
+               owner->area.num_niovs = len / PAGE_SIZE;
                owner->binding = binding;
 
                err = gen_pool_add_owner(binding->chunk_pool, dma_addr,
@@ -275,17 +276,17 @@ net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
                        goto err_free_chunks;
                }
 
-               owner->niovs = kvmalloc_array(owner->num_niovs,
-                                             sizeof(*owner->niovs),
-                                             GFP_KERNEL);
-               if (!owner->niovs) {
+               owner->area.niovs = kvmalloc_array(owner->area.num_niovs,
+                                                  sizeof(*owner->area.niovs),
+                                                  GFP_KERNEL);
+               if (!owner->area.niovs) {
                        err = -ENOMEM;
                        goto err_free_chunks;
                }
 
-               for (i = 0; i < owner->num_niovs; i++) {
-                       niov = &owner->niovs[i];
-                       niov->owner = owner;
+               for (i = 0; i < owner->area.num_niovs; i++) {
+                       niov = &owner->area.niovs[i];
+                       niov->owner = &owner->area;
                        page_pool_set_dma_addr_netmem(net_iov_to_netmem(niov),
                                                      net_devmem_get_dma_addr(niov));
                }

diff --git a/net/core/devmem.h b/net/core/devmem.h
index 99782ddeca40859e9107620c22b3150ad3d10a85..a2b9913e9a171bf628467d492c5ebb7569c21996 100644 (file)
--- a/net/core/devmem.h
+++ b/net/core/devmem.h
@@ -10,6 +10,8 @@
 #ifndef _NET_DEVMEM_H
 #define _NET_DEVMEM_H
 
+#include <net/netmem.h>
+
 struct netlink_ext_ack;
 
 struct net_devmem_dmabuf_binding {
@@ -51,17 +53,11 @@ struct net_devmem_dmabuf_binding {
  * allocations from this chunk.
  */
 struct dmabuf_genpool_chunk_owner {
-       /* Offset into the dma-buf where this chunk starts.  */
-       unsigned long base_virtual;
+       struct net_iov_area area;
+       struct net_devmem_dmabuf_binding *binding;
 
        /* dma_addr of the start of the chunk.  */
        dma_addr_t base_dma_addr;
-
-       /* Array of net_iovs for this chunk. */
-       struct net_iov *niovs;
-       size_t num_niovs;
-
-       struct net_devmem_dmabuf_binding *binding;
 };
 
 void __net_devmem_dmabuf_binding_free(struct net_devmem_dmabuf_binding *binding);
@@ -75,20 +71,17 @@ int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
 void dev_dmabuf_uninstall(struct net_device *dev);
 
 static inline struct dmabuf_genpool_chunk_owner *
-net_iov_owner(const struct net_iov *niov)
+net_devmem_iov_to_chunk_owner(const struct net_iov *niov)
 {
-       return niov->owner;
-}
+       struct net_iov_area *owner = net_iov_owner(niov);
 
-static inline unsigned int net_iov_idx(const struct net_iov *niov)
-{
-       return niov - net_iov_owner(niov)->niovs;
+       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_iov_owner(niov)->binding;
+       return net_devmem_iov_to_chunk_owner(niov)->binding;
 }
 
 static inline u32 net_devmem_iov_binding_id(const struct net_iov *niov)
@@ -98,7 +91,7 @@ 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 *owner = net_iov_owner(niov);
+       struct net_iov_area *owner = net_iov_owner(niov);
 
        return owner->base_virtual +
               ((unsigned long)net_iov_idx(niov) << PAGE_SHIFT);