From e9f3d61db5cb29b3f17f0dc40c3ec2cda2ee93e5 Mon Sep 17 00:00:00 2001 From: Mina Almasry Date: Thu, 8 May 2025 00:48:22 +0000 Subject: net: add get_netmem/put_netmem support Currently net_iovs support only pp ref counts, and do not support a page ref equivalent. This is fine for the RX path as net_iovs are used exclusively with the pp and only pp refcounting is needed there. The TX path however does not use pp ref counts, thus, support for get_page/put_page equivalent is needed for netmem. Support get_netmem/put_netmem. Check the type of the netmem before passing it to page or net_iov specific code to obtain a page ref equivalent. For dmabuf net_iovs, we obtain a ref on the underlying binding. This ensures the entire binding doesn't disappear until all the net_iovs have been put_netmem'ed. We do not need to track the refcount of individual dmabuf net_iovs as we don't allocate/free them from a pool similar to what the buddy allocator does for pages. This code is written to be extensible by other net_iov implementers. get_netmem/put_netmem will check the type of the netmem and route it to the correct helper: pages -> [get|put]_page() dmabuf net_iovs -> net_devmem_[get|put]_net_iov() new net_iovs -> new helpers Signed-off-by: Mina Almasry Acked-by: Stanislav Fomichev Link: https://patch.msgid.link/20250508004830.4100853-3-almasrymina@google.com Signed-off-by: Paolo Abeni --- net/core/devmem.h | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'net/core/devmem.h') diff --git a/net/core/devmem.h b/net/core/devmem.h index 7fc158d52729..946f2e015746 100644 --- a/net/core/devmem.h +++ b/net/core/devmem.h @@ -29,6 +29,10 @@ struct net_devmem_dmabuf_binding { * The binding undos itself and unmaps the underlying dmabuf once all * those refs are dropped and the binding is no longer desired or in * use. + * + * 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. */ refcount_t ref; @@ -111,6 +115,9 @@ net_devmem_dmabuf_binding_put(struct net_devmem_dmabuf_binding *binding) __net_devmem_dmabuf_binding_free(binding); } +void net_devmem_get_net_iov(struct net_iov *niov); +void net_devmem_put_net_iov(struct net_iov *niov); + struct net_iov * net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding); void net_devmem_free_dmabuf(struct net_iov *ppiov); @@ -120,6 +127,19 @@ bool net_is_devmem_iov(struct net_iov *niov); #else struct net_devmem_dmabuf_binding; +static inline void +net_devmem_dmabuf_binding_put(struct net_devmem_dmabuf_binding *binding) +{ +} + +static inline void net_devmem_get_net_iov(struct net_iov *niov) +{ +} + +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) { -- cgit v1.2.3