[PATCH net-next] net: devmem: remove net_iov_area base_virtual

[PATCH net-next] net: devmem: remove net_iov_area base_virtual

[Stanislav Fomichev]

Since commit 083e64a3af77 ("net: devmem: replace gen_pool with
freelist"), a binding has a single net_iov_area covering the whole
dma-buf, and base_virtual is always 0. Its only reader is
net_iov_virtual_addr(), where it adds nothing. io_uring zcrx never
uses it.

Drop the field and the store, and compute the dma-buf offset from the
net_iov index alone.

No functional change. From review feedback on:
https://lore.kernel.org/netdev/asPUZ8DPllHd6Yu9@devvm7509.cco0.facebook.com/

Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
---
 include/net/netmem.h | 3 ---
 net/core/devmem.c    | 1 -
 net/core/devmem.h    | 3 +--
 3 files changed, 1 insertion(+), 6 deletions(-)

diff --git a/include/net/netmem.h b/include/net/netmem.h
index cc97611632dc..0cc8572f62ca 100644
--- a/include/net/netmem.h
+++ b/include/net/netmem.h
@@ -102,9 +102,6 @@ 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;
 };
 
 static inline struct net_iov_area *net_iov_owner(const struct net_iov *niov)
diff --git a/net/core/devmem.c b/net/core/devmem.c
index 71c83730d73d..07c62e2e3088 100644
--- a/net/core/devmem.c
+++ b/net/core/devmem.c
@@ -252,7 +252,6 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev,
 		goto err_unmap;
 	}
 
-	binding->area.base_virtual = 0;
 	binding->area.num_niovs = dmabuf->size >> niov_shift;
 	if (direction == DMA_TO_DEVICE) {
 		binding->tx_vec = kvmalloc_objs(struct net_iov *,
diff --git a/net/core/devmem.h b/net/core/devmem.h
index 28d6fa7bcb57..1cec10f0257c 100644
--- a/net/core/devmem.h
+++ b/net/core/devmem.h
@@ -112,8 +112,7 @@ static inline unsigned long net_iov_virtual_addr(const struct net_iov *niov)
 	struct net_devmem_dmabuf_binding *binding =
 		net_devmem_iov_binding(niov);
 
-	return net_iov_owner(niov)->base_virtual +
-	       ((unsigned long)net_iov_idx(niov) << binding->niov_shift);
+	return (unsigned long)net_iov_idx(niov) << binding->niov_shift;
 }
 
 static inline bool
-- 
2.53.0-Meta

Re: [PATCH net-next] net: devmem: remove net_iov_area base_virtual

[Mina Almasry]

On Mon, Oct 5, 2026 at 1:18 PM Stanislav Fomichev <sdf.kernel@gmail.com> wrote:
>
> Since commit 083e64a3af77 ("net: devmem: replace gen_pool with
> freelist"), a binding has a single net_iov_area covering the whole
> dma-buf, and base_virtual is always 0. Its only reader is
> net_iov_virtual_addr(), where it adds nothing. io_uring zcrx never
> uses it.
>
> Drop the field and the store, and compute the dma-buf offset from the
> net_iov index alone.
>
> No functional change. From review feedback on:
> https://lore.kernel.org/netdev/asPUZ8DPllHd6Yu9@devvm7509.cco0.facebook.com/
>
> Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>

Acked-by: Mina Almasry <almasrymina@google.com>

-- 
Thanks,
Mina

Re: [PATCH net-next] net: devmem: remove net_iov_area base_virtual

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Mon,  5 Oct 2026 13:18:22 -0700 you wrote:
> Since commit 083e64a3af77 ("net: devmem: replace gen_pool with
> freelist"), a binding has a single net_iov_area covering the whole
> dma-buf, and base_virtual is always 0. Its only reader is
> net_iov_virtual_addr(), where it adds nothing. io_uring zcrx never
> uses it.
> 
> Drop the field and the store, and compute the dma-buf offset from the
> net_iov index alone.
> 
> [...]

Here is the summary with links:
  - [net-next] net: devmem: remove net_iov_area base_virtual
    https://git.kernel.org/netdev/net-next/c/7d3e5984d0fc

You are awesome, thank you!
-- 
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