Implement netdev devmem allocator. The allocator takes a given struct
netdev_dmabuf_binding as input and allocates net_iov from that
binding.
The allocation simply delegates to the binding's genpool for the
allocation logic and wraps the returned memory region in a net_iov
struct.
Signed-off-by: Willem de Bruijn <willemb@xxxxxxxxxx>
Signed-off-by: Kaiyuan Zhang <kaiyuanz@xxxxxxxxxx>
Signed-off-by: Mina Almasry <almasrymina@xxxxxxxxxx>
---
v6:
- Add comment on net_iov_dma_addr to explain why we don't use
niov->dma_addr (Pavel)
- Refactor new functions into net/core/devmem.c (Pavel)
v1:
- Rename devmem -> dmabuf (David).
---
include/net/devmem.h | 12 ++++++++++++
include/net/netmem.h | 40 ++++++++++++++++++++++++++++++++++++++++
net/core/devmem.c | 38 ++++++++++++++++++++++++++++++++++++++
3 files changed, 90 insertions(+)
diff --git a/include/net/devmem.h b/include/net/devmem.h
index 85ccbbe84c65..4207adadc2bb 100644
--- a/include/net/devmem.h
+++ b/include/net/devmem.h
@@ -67,6 +67,8 @@ struct dmabuf_genpool_chunk_owner {
};
#ifdef CONFIG_DMA_SHARED_BUFFER
+struct net_iov *netdev_alloc_dmabuf(struct netdev_dmabuf_binding *binding);
+void netdev_free_dmabuf(struct net_iov *ppiov);
void __netdev_dmabuf_binding_free(struct netdev_dmabuf_binding *binding);
int netdev_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
struct netdev_dmabuf_binding **out);
@@ -74,6 +76,16 @@ void netdev_unbind_dmabuf(struct netdev_dmabuf_binding *binding);
int netdev_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
struct netdev_dmabuf_binding *binding);
#else
+static inline struct net_iov *
+netdev_alloc_dmabuf(struct netdev_dmabuf_binding *binding)
+{
+ return NULL;
+}
+
+static inline void netdev_free_dmabuf(struct net_iov *ppiov)
+{
+}
+
static inline void
__netdev_dmabuf_binding_free(struct netdev_dmabuf_binding *binding)
{
diff --git a/include/net/netmem.h b/include/net/netmem.h
index 72e932a1a948..ca17ea1d33f8 100644
--- a/include/net/netmem.h
+++ b/include/net/netmem.h
@@ -14,8 +14,48 @@
struct net_iov {
struct dmabuf_genpool_chunk_owner *owner;
+ unsigned long dma_addr;
};
+static inline struct dmabuf_genpool_chunk_owner *
+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;
+}
+
+/* This returns the absolute dma_addr_t calculated from
+ * net_iov_owner(niov)->owner->base_dma_addr, not the page_pool-owned
+ * niov->dma_addr.
+ *
+ * The absolute dma_addr_t is a dma_addr_t that is always uncompressed.
+ *
+ * The page_pool-owner niov->dma_addr is the absolute dma_addr compressed into
+ * an unsigned long. Special handling is done when the unsigned long is 32-bit
+ * but the dma_addr_t is 64-bit.
+ *
+ * In general code looking for the dma_addr_t should use net_iov_dma_addr(),
+ * while page_pool code looking for the unsigned long dma_addr which mirrors
+ * the field in struct page should use niov->dma_addr.
+ */
+static inline dma_addr_t net_iov_dma_addr(const struct net_iov *niov)
+{
+ struct dmabuf_genpool_chunk_owner *owner = net_iov_owner(niov);
+
+ return owner->base_dma_addr +
+ ((dma_addr_t)net_iov_idx(niov) << PAGE_SHIFT);
+}
+
+static inline struct netdev_dmabuf_binding *
+net_iov_binding(const struct net_iov *niov)
+{
+ return net_iov_owner(niov)->binding;
+}
+
/* netmem */
/**
diff --git a/net/core/devmem.c b/net/core/devmem.c
index 779ad990971e..57d3a1f223ef 100644
--- a/net/core/devmem.c
+++ b/net/core/devmem.c
@@ -93,6 +93,44 @@ static int netdev_restart_rx_queue(struct net_device *dev, int rxq_idx)
return err;
}
+struct net_iov *netdev_alloc_dmabuf(struct netdev_dmabuf_binding *binding)
+{
+ struct dmabuf_genpool_chunk_owner *owner;
+ unsigned long dma_addr;
+ struct net_iov *niov;
+ ssize_t offset;
+ ssize_t index;
+
+ dma_addr = gen_pool_alloc_owner(binding->chunk_pool, PAGE_SIZE,
+ (void **)&owner);
+ if (!dma_addr)
+ return NULL;
+
+ offset = dma_addr - owner->base_dma_addr;
+ index = offset / PAGE_SIZE;
+ niov = &owner->niovs[index];
+
+ niov->pp_magic = 0;
+ niov->pp = NULL;
+ niov->dma_addr = 0;
+ atomic_long_set(&niov->pp_ref_count, 0);
+
+ netdev_dmabuf_binding_get(binding);
+
+ return niov;
+}
+
+void netdev_free_dmabuf(struct net_iov *niov)
+{
+ struct netdev_dmabuf_binding *binding = net_iov_binding(niov);
+ unsigned long dma_addr = net_iov_dma_addr(niov);
+
+ if (gen_pool_has_addr(binding->chunk_pool, dma_addr, PAGE_SIZE))
+ gen_pool_free(binding->chunk_pool, dma_addr, PAGE_SIZE);
+
+ netdev_dmabuf_binding_put(binding);
+}
+
/* Protected by rtnl_lock() */
static DEFINE_XARRAY_FLAGS(netdev_dmabuf_bindings, XA_FLAGS_ALLOC1);
--
2.44.0.rc1.240.g4c46232300-goog
