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@google.com Signed-off-by: Kaiyuan Zhang kaiyuanz@google.com Signed-off-by: Mina Almasry almasrymina@google.com
---
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);