From: David Wei <dw@davidwei.uk>
To: Mina Almasry <almasrymina@google.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
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Cc: "Donald Hunter" <donald.hunter@gmail.com>,
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Subject: Re: [PATCH net-next v9 05/14] netdev: netdevice devmem allocator
Date: Fri, 17 May 2024 17:39:25 -0700 [thread overview]
Message-ID: <090be3c0-42e6-4b97-8b03-eb64b06a2911@davidwei.uk> (raw)
In-Reply-To: <20240510232128.1105145-6-almasrymina@google.com>
On 2024-05-10 16:21, Mina Almasry wrote:
> +/* 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);
> +}
This part feels like devmem TCP specific, yet the function is in
netmem.h. Please consider moving it into devmem.{h,c} which makes it
less likely that people not reading your comment will try using it.
> +
> +static inline struct net_devmem_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 d82f92d7cf9ce..1f90e23a81441 100644
> --- a/net/core/devmem.c
> +++ b/net/core/devmem.c
> @@ -54,6 +54,42 @@ void __net_devmem_dmabuf_binding_free(struct net_devmem_dmabuf_binding *binding)
> kfree(binding);
> }
>
> +struct net_iov *
> +net_devmem_alloc_dmabuf(struct net_devmem_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->dma_addr = 0;
> +
> + net_devmem_dmabuf_binding_get(binding);
> +
> + return niov;
> +}
> +
> +void net_devmem_free_dmabuf(struct net_iov *niov)
> +{
> + struct net_devmem_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);
> +
> + net_devmem_dmabuf_binding_put(binding);
> +}
> +
> /* Protected by rtnl_lock() */
> static DEFINE_XARRAY_FLAGS(net_devmem_dmabuf_bindings, XA_FLAGS_ALLOC1);
>
next prev parent reply other threads:[~2024-05-18 0:39 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-10 23:21 [PATCH net-next v9 00/14] Device Memory TCP Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 01/14] netdev: add netdev_rx_queue_restart() Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 02/14] net: page_pool: create hooks for custom page providers Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 03/14] net: netdev netlink api to bind dma-buf to a net device Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 04/14] netdev: support binding dma-buf to netdevice Mina Almasry
2024-05-15 10:01 ` Nikolay Aleksandrov
2024-05-15 10:19 ` Nikolay Aleksandrov
2024-05-18 18:46 ` David Wei
2024-05-29 19:49 ` Mina Almasry
2024-05-18 18:57 ` David Wei
2024-05-10 23:21 ` [PATCH net-next v9 05/14] netdev: netdevice devmem allocator Mina Almasry
2024-05-18 0:39 ` David Wei [this message]
2024-05-10 23:21 ` [PATCH net-next v9 06/14] page_pool: convert to use netmem Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 07/14] page_pool: devmem support Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 08/14] memory-provider: dmabuf devmem memory provider Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 09/14] net: support non paged skb frags Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 10/14] net: add support for skbs with unreadable frags Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 11/14] tcp: RX path for devmem TCP Mina Almasry
2024-05-23 6:02 ` David Wei
2024-05-28 17:36 ` Mina Almasry
2024-05-29 2:42 ` Pavel Begunkov
2024-05-29 17:20 ` Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 12/14] net: add SO_DEVMEM_DONTNEED setsockopt to release RX frags Mina Almasry
2024-05-15 9:52 ` Nikolay Aleksandrov
2024-05-10 23:21 ` [PATCH net-next v9 13/14] net: add devmem TCP documentation Mina Almasry
2024-05-10 23:21 ` [PATCH net-next v9 14/14] selftests: add ncdevmem, netcat for devmem TCP Mina Almasry
2024-05-13 23:31 ` [PATCH net-next v9 00/14] Device Memory TCP Jakub Kicinski
2024-05-14 17:15 ` Mina Almasry
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