[PATCH v2 bpf] xsk: Fix offset calculation in unaligned mode

[PATCH v2 bpf] xsk: Fix offset calculation in unaligned mode

[e.kubanski]

Bring back previous offset calculation behaviour
in AF_XDP unaligned umem mode.

In unaligned mode, upper 16 bits should contain
data offset, lower 48 bits should contain
only specific chunk location without offset.

Remove pool->headroom duplication into 48bit address.

Signed-off-by: Eryk Kubanski <e.kubanski@partner.samsung.com>
Fixes: bea14124bacb ("xsk: Get rid of xdp_buff_xsk::orig_addr")
---
 include/net/xsk_buff_pool.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/xsk_buff_pool.h b/include/net/xsk_buff_pool.h
index 7f0a75d6563d..b3699a848844 100644
--- a/include/net/xsk_buff_pool.h
+++ b/include/net/xsk_buff_pool.h
@@ -232,8 +232,8 @@ static inline u64 xp_get_handle(struct xdp_buff_xsk *xskb,
 		return orig_addr;
 
 	offset = xskb->xdp.data - xskb->xdp.data_hard_start;
-	orig_addr -= offset;
 	offset += pool->headroom;
+	orig_addr -= offset;
 	return orig_addr + (offset << XSK_UNALIGNED_BUF_OFFSET_SHIFT);
 }
 
-- 
2.34.1

Re: [PATCH v2 bpf] xsk: Fix offset calculation in unaligned mode

[Magnus Karlsson]

On Wed, 16 Apr 2025 at 13:30, e.kubanski <e.kubanski@partner.samsung.com> wrote:
>
> Bring back previous offset calculation behaviour
> in AF_XDP unaligned umem mode.
>
> In unaligned mode, upper 16 bits should contain
> data offset, lower 48 bits should contain
> only specific chunk location without offset.
>
> Remove pool->headroom duplication into 48bit address.

Thanks Eryk.

Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>

> Signed-off-by: Eryk Kubanski <e.kubanski@partner.samsung.com>
> Fixes: bea14124bacb ("xsk: Get rid of xdp_buff_xsk::orig_addr")
> ---
>  include/net/xsk_buff_pool.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/net/xsk_buff_pool.h b/include/net/xsk_buff_pool.h
> index 7f0a75d6563d..b3699a848844 100644
> --- a/include/net/xsk_buff_pool.h
> +++ b/include/net/xsk_buff_pool.h
> @@ -232,8 +232,8 @@ static inline u64 xp_get_handle(struct xdp_buff_xsk *xskb,
>                 return orig_addr;
>
>         offset = xskb->xdp.data - xskb->xdp.data_hard_start;
> -       orig_addr -= offset;
>         offset += pool->headroom;
> +       orig_addr -= offset;
>         return orig_addr + (offset << XSK_UNALIGNED_BUF_OFFSET_SHIFT);
>  }
>
> --
> 2.34.1
>
>

Re: [PATCH v2 bpf] xsk: Fix offset calculation in unaligned mode

[patchwork-bot+netdevbpf]

Hello:

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

On Wed, 16 Apr 2025 13:29:25 +0200 you wrote:
> Bring back previous offset calculation behaviour
> in AF_XDP unaligned umem mode.
> 
> In unaligned mode, upper 16 bits should contain
> data offset, lower 48 bits should contain
> only specific chunk location without offset.
> 
> [...]

Here is the summary with links:
  - [v2,bpf] xsk: Fix offset calculation in unaligned mode
    https://git.kernel.org/netdev/net/c/bf20af079099

You are awesome, thank you!
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