From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-dy1-f200.google.com (mail-dy1-f200.google.com [74.125.82.200]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E83C33D8903 for ; Sat, 10 Oct 2026 08:39:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.200 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791621586; cv=none; b=BKHZwUQdx8oezyqw5NiUHHhlgFkUyMHAL5GWSQqOquZ5TtsDa7LCkmCBWJRQIZzEdmZn+zuXftDtcVKFKJDTp7epw6Jdbfs0iBJ3NSRlEwicVTw1NLxguyyggX1XQO2oSgkibc4UezsV/KU3DyJ0r9VQVhUkc2krSAJz7kr3tPc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791621586; c=relaxed/simple; bh=/LLvU+5AnYzTjy57lN2tpyIzvmdHROTfxW0jkjFEfuA=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=QZyLaRJIGQ2r7AKbVOnKxKbiEqoIjy5LG6njx3mluCC5V9RWRQTIcMIHXPgso2Uxbyfohlt6T6m2rdbZ+eoXO+JcXhVsPIKmrHDV0xtGKezbvX5HD+o0a8YPV3hqFx4tKZrLFpED4WcaGuJ0j6POXi7p64jehjFe57CAUHjdyCI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--almasrymina.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=dlPpSfmU; arc=none smtp.client-ip=74.125.82.200 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--almasrymina.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="dlPpSfmU" Received: by mail-dy1-f200.google.com with SMTP id 5a478bee46e88-358856e5105so1349747eec.0 for ; Sat, 10 Oct 2026 01:39:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1791621580; x=1792226380; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=oMs6zujZVOhihfnpjH1h+iJn7PnD9P9Ohm7NiW91TsM=; b=dlPpSfmULiFiON0icXljxQWbgzaOtv3rM42WB0uaZoZtNCriy5hvcJu5mNZV3L1u9b lzazIw07/CT5fGccBcbAMduVypLd75/fEDigHntkcP++BeMqdlvnzLPV+BI0JN0YYLeL N3jzdPV2WnYhHCAanJBhmLr3Pm8Z7yPEIO1e7eftEVP0RT3CZmdVEtEZAy86xmdi5UhJ NJXcg4zfOy25E3p4rTbBk7yrG9fz5F/Gy1zu6TB7Zfwpz5c97I6xxVVMQUyk7XFEAlMg qYrYk3iRkt8XLqzxRm2fZ7qribJDNWiamO8FMfW+o9zc1QCHm7s0Qwh62MbHvVZaKwtM g/7w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1791621580; x=1792226380; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=oMs6zujZVOhihfnpjH1h+iJn7PnD9P9Ohm7NiW91TsM=; b=fN1/JOYHMY9NxWiCzDUmOl7rjKmadC5OdGoeaz+aYu2SQGA8lsj/WKj7dJwUq3KvAH jw1nVtn3YxbloNJCNZNMmVgFh7nzzM229J5nKQA45yYctMucmai9KEgGQbA6qX8Z99NG znCcIfqtGijUHsplkZqh0vrWNzlXu0Ug2ECOX3iRLE6v2EoTVmxhLyHBUyQQQTgORfFC 1/5QjzO8SMmBR8VJ1TI/g0DdKNqY2V0JXV+KoM3MS05MTRAKpFWKOVrhCiOCnPpr7Dy7 femqskZLONZIZDlGL8T66x88iJ7ogA4W1pGrOiUkIx2j3YWP3/yzw/H90Z34pw4K8Fx7 mfGw== X-Gm-Message-State: AFq9FYIEap9C9Iz99D1nGoGN8sMPZNb7u0l5aR+c41dAndstqjj3Qgm9 73NUwocz0Gxl1jclXr4rx8kuel/4lNVvxAs/ySxILmWofp5oKS8AeivLyqbeIMYyYZzFGSTA/oj 0nI/cxdVxydJc6n7x2KyRO9U99oDyJQ2ltKxsCb3azeWLUmptI0Gml2k0AwZeyzuWdblJnz/oU7 nDDd3h1jzHjib13eB6tTCv/vYLh6q1+cP8V1DS4SspFvDV7fc6hHjreRPK3dZM7WM= X-Received: from dycc9.prod.google.com ([2002:a05:693c:60c9:b0:351:4a84:2505]) (user=almasrymina job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7301:1a05:b0:358:eccb:af7c with SMTP id 5a478bee46e88-358eccbc89dmr38890eec.33.1791621577801; Sat, 10 Oct 2026 01:39:37 -0700 (PDT) Date: Sat, 10 Oct 2026 08:38:43 +0000 In-Reply-To: <20261010083935.3274178-1-almasrymina@google.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20261010083935.3274178-1-almasrymina@google.com> X-Mailer: git-send-email 2.56.0.385.gd3acb90ef8-goog Message-ID: <20261010083935.3274178-3-almasrymina@google.com> Subject: [PATCH net-next v1 2/6] net: skbuff: add napi_pp_get_page() and use it in tcp_recvmsg_dmabuf() From: Mina Almasry To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, bpf@vger.kernel.org Cc: Mina Almasry , Ayush Sawal , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Tariq Toukan , Simon Horman , Steffen Klassert , Herbert Xu , Neal Cardwell , Kuniyuki Iwashima , John Fastabend , Sabrina Dubroca , Eric Biggers , Kees Cook , Michael Grzeschik , "=?UTF-8?q?Uwe=20Kleine-K=C3=B6nig=20=28The=20Capable=20Hub=29?=" , Petr Machata , Arend van Spriel , Jakub Raczynski Content-Type: text/plain; charset="UTF-8" While napi_pp_put_page() releases a page_pool pp_ref_count reference on a netmem, no symmetric helper existed to acquire one, forcing callers like tcp_recvmsg_dmabuf() to open-code atomic_long_inc() on niov->desc.pp_ref_count. Add napi_pp_get_page() to pair symmetrically with napi_pp_put_page(), and use WARN_ON_ONCE(!napi_pp_get_page(netmem)) in tcp_recvmsg_dmabuf() to match WARN_ON_ONCE(!napi_pp_put_page(netmem)) in tcp_release_user_frags(). Signed-off-by: Mina Almasry --- include/linux/skbuff_ref.h | 2 ++ net/core/skbuff.c | 31 +++++++++++++++++++++++++++++++ net/ipv4/tcp.c | 6 ++++-- 3 files changed, 37 insertions(+), 2 deletions(-) diff --git a/include/linux/skbuff_ref.h b/include/linux/skbuff_ref.h index 05c8486bafac8..0441c220fdbdf 100644 --- a/include/linux/skbuff_ref.h +++ b/include/linux/skbuff_ref.h @@ -9,6 +9,8 @@ #include +bool napi_pp_get_page(netmem_ref netmem); + /** * __skb_frag_ref - take an addition reference on a paged fragment. * @frag: the paged fragment diff --git a/net/core/skbuff.c b/net/core/skbuff.c index b459264ba5180..8a8be746828db 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1026,6 +1026,15 @@ int skb_cow_data_for_xdp(struct page_pool *pool, struct sk_buff **pskb, EXPORT_SYMBOL(skb_cow_data_for_xdp); #if IS_ENABLED(CONFIG_PAGE_POOL) +/** + * napi_pp_put_page - release a page_pool reference on a netmem + * @netmem: netmem to unreference + * + * Drops a page_pool reference (pp_ref_count) on @netmem if it belongs to a + * page_pool. Counterpart to napi_pp_get_page(). + * + * Return: true if @netmem belongs to a page_pool, false otherwise. + */ bool napi_pp_put_page(netmem_ref netmem) { netmem = netmem_compound_head(netmem); @@ -1038,6 +1047,28 @@ bool napi_pp_put_page(netmem_ref netmem) return true; } EXPORT_SYMBOL(napi_pp_put_page); + +/** + * napi_pp_get_page - acquire a page_pool reference on a netmem + * @netmem: netmem to reference + * + * Acquires a page_pool reference (pp_ref_count) on @netmem if it belongs to a + * page_pool. Counterpart to napi_pp_put_page(). + * + * Return: true if @netmem belongs to a page_pool, false otherwise. + */ +bool napi_pp_get_page(netmem_ref netmem) +{ + netmem = netmem_compound_head(netmem); + + if (unlikely(!netmem_is_pp(netmem))) + return false; + + page_pool_ref_netmem(netmem); + + return true; +} +EXPORT_SYMBOL(napi_pp_get_page); #endif static bool skb_pp_recycle(struct sk_buff *skb, void *data) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index f4c9101e5996a..99d7237a623d8 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -254,6 +254,7 @@ #include #include #include +#include #include #include #include @@ -2559,6 +2560,7 @@ static int tcp_recvmsg_dmabuf(struct sock *sk, const struct sk_buff *skb, */ for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; + netmem_ref netmem = skb_frag_netmem(frag); struct net_iov *niov; u64 frag_offset; int end; @@ -2612,8 +2614,8 @@ static int tcp_recvmsg_dmabuf(struct sock *sk, const struct sk_buff *skb, if (err) goto out; - atomic_long_inc(&niov->desc.pp_ref_count); - tcp_xa_pool.netmems[tcp_xa_pool.idx++] = skb_frag_netmem(frag); + WARN_ON_ONCE(!napi_pp_get_page(netmem)); + tcp_xa_pool.netmems[tcp_xa_pool.idx++] = netmem; sent += copy; -- 2.56.0.385.gd3acb90ef8-goog