netdev - Re: [PATCH net-next v5 2/4] net: devmem: refactor sock_devmem

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Message-ID: <CAHS8izNB6s97X8srfZQ1upUNOOx0vwj4Aa9gMUZvneoyefqdrw@mail.gmail.com>
Date: Mon, 27 Oct 2025 17:36:35 -0700
From: Mina Almasry <almasrymina@...gle.com>
To: Bobby Eshleman <bobbyeshleman@...il.com>
Cc: "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
	Kuniyuki Iwashima <kuniyu@...gle.com>, Willem de Bruijn <willemb@...gle.com>, 
	Neal Cardwell <ncardwell@...gle.com>, David Ahern <dsahern@...nel.org>, 
	Stanislav Fomichev <sdf@...ichev.me>, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Bobby Eshleman <bobbyeshleman@...a.com>
Subject: Re: [PATCH net-next v5 2/4] net: devmem: refactor sock_devmem_dontneed
 for autorelease split

On Thu, Oct 23, 2025 at 2:00 PM Bobby Eshleman <bobbyeshleman@...il.com> wrote:
>
> From: Bobby Eshleman <bobbyeshleman@...a.com>
>
> Refactor sock_devmem_dontneed() in preparation for supporting both
> autorelease and manual token release modes.
>
> Split the function into two parts:
> - sock_devmem_dontneed(): handles input validation, token allocation,
>   and copying from userspace
> - sock_devmem_dontneed_autorelease(): performs the actual token release
>   via xarray lookup and page pool put
>
> This separation allows a future commit to add a parallel
> sock_devmem_dontneed_manual_release() function that uses a different
> token tracking mechanism (per-niov reference counting) without
> duplicating the input validation logic.
>
> The refactoring is purely mechanical with no functional change. Only
> intended to minimize the noise in subsequent patches.
>
> Signed-off-by: Bobby Eshleman <bobbyeshleman@...a.com>
> ---
>  net/core/sock.c | 52 ++++++++++++++++++++++++++++++++--------------------
>  1 file changed, 32 insertions(+), 20 deletions(-)
>
> diff --git a/net/core/sock.c b/net/core/sock.c
> index a99132cc0965..e7b378753763 100644
> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -1082,30 +1082,13 @@ static int sock_reserve_memory(struct sock *sk, int bytes)
>  #define MAX_DONTNEED_FRAGS 1024
>
>  static noinline_for_stack int
> -sock_devmem_dontneed(struct sock *sk, sockptr_t optval, unsigned int optlen)
> +sock_devmem_dontneed_autorelease(struct sock *sk, struct dmabuf_token *tokens,

Kind of a misnomer. This helper doesn't seem to autorelease, but
really release the provided tokens, I guess. I would have
sock_devmem_dontneed_tokens, but naming is hard :D

Either way, looks correct code move,

Reviewed-by: Mina Almasry <almasrymina@...gle.com>