From patchwork Tue Jan 23 22:17:45 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mina Almasry X-Patchwork-Id: 13528209 X-Patchwork-Delegate: kuba@kernel.org Received: from mail-yb1-f201.google.com (mail-yb1-f201.google.com [209.85.219.201]) (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 362EE4F217 for ; Tue, 23 Jan 2024 22:17:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706048279; cv=none; b=NR7zU970z8SdZuaQmkJC9JoS+EbW/fVeJv/wA00s68/4w8sogLe6NaqBnuuzINdKDWRskpvlWmk+D1qUXYB2zr9PnXUTV9h7r0cHISyD+tMA/UL7dO2Av2G43IlxBqkBuwQTSQilQhzhrqZ7FAfJ+Wo3NGskQbnAL7S2j/I3NGM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706048279; c=relaxed/simple; bh=eQc/0XprESJCX8/SL8NWCcerd2+39PRmvZ4jwBgHHms=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=kB6Xt7LTBC4xPfoA9ULtufXQiscV9k4SPr8dTa2yuVBdIN6IGvYOBhErpuD5KM7gorrLPwCI9D0t7nlXK9c8CNrOR2zqN/09dbjvaiDxR9np3z3RXN3ircnqDOR8I13cq9seyNZBcYBTbtXAo5jJKX/iVxO1Pq9hlbSnSPd+Q5M= 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=bvAyWCgT; arc=none smtp.client-ip=209.85.219.201 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="bvAyWCgT" Received: by mail-yb1-f201.google.com with SMTP id 3f1490d57ef6-dc3645a6790so3449833276.0 for ; Tue, 23 Jan 2024 14:17:56 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1706048276; x=1706653076; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=sq2A5rdPoZzXe3JfsyjEi2DmgNcsMleYf8+7wJXU3oU=; b=bvAyWCgTdB7xqhlCHl4FccHzz0TK4HuT69XojP7Cihu+xUqrUNsjr6aNdFRlc0lsA6 oVP+JJe+KMh22It+JjF8vj3488kwKDj6QU20MRaBCLEZ1i8xL+HzBcyLfACMM/GAmzkc KTaARTv6Pgz+NXkYt8/JkL35I0bDegpG5Eug7Ry8RDHnbw34yfpkPqaeKOO7bph7hcCb Hz3IzdfhsiEoI7zRO/kpcKycv9QKpLW7Gqcl/msLocu02G6gQCaYgUYPyWAzNu5qRZUj 2Z7BEswmWXCYGl6FBdDwUgEIgTT8CGLjVoEGurlb5lE3NpvaAlXYiFfM8/E8QngSuMFR shoQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1706048276; x=1706653076; h=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; bh=sq2A5rdPoZzXe3JfsyjEi2DmgNcsMleYf8+7wJXU3oU=; b=VW7LSinO9H/qaSG7tjeq8CPOWkbIqavJRhwchifhgLAFiseCtqt1XrsBCjwcd1BGoV Qyppm+QUrVSwTg8DqMffqGIBIW7hMko2vTkKy5o/6SAJENOnL4lGQPLxiPhpzLCx5vSe Bqs14YysshAIBlfnlfvFxKdICBIhIGWOzzMbe2u2KAftoeyyaAnwPXDwFIKAT0EdEisU sJz3kBLHBtOlecjpjH0IwiXGxZ5QJ+tmiABAqhWrrCWZi2Lzq8G/d6RaEnRZ4KM3z38B 4aKO3dbBQe/mkjBA0VNdPRZg+whMtmOLV+6vsbfqC7KrEA1TRNPWwDnBg50aPilTabLW FTJQ== X-Gm-Message-State: AOJu0YzJSCQvBUy8nnxEBrtRyFzqH6/2/0tEYZ5IdhwZa1wJru97sJKs +BLTN7uZTJSq9ybMoUqxQibpmguIW8c09y5JGqczKN+XSt0HA698ZkmC4vLlLs6VFNV0kwxWwOa wqkCuSGWLSilOfmOWqFJWbw== X-Google-Smtp-Source: AGHT+IH87J0v28hXMQrSfT2AvSQ99998vzYrtkl0Kh0l9IUSxf/Sr2m7Wvvoa8btav6qxFFlBuAzv1P6tFn0ptW02Q== X-Received: from almasrymina.svl.corp.google.com ([2620:15c:2c4:200:3608:aa16:52d:3594]) (user=almasrymina job=sendgmr) by 2002:a05:6902:86:b0:dbe:a214:888c with SMTP id h6-20020a056902008600b00dbea214888cmr3189553ybs.11.1706048276193; Tue, 23 Jan 2024 14:17:56 -0800 (PST) Date: Tue, 23 Jan 2024 14:17:45 -0800 In-Reply-To: <20240123221749.793069-1-almasrymina@google.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240123221749.793069-1-almasrymina@google.com> X-Mailer: git-send-email 2.43.0.429.g432eaa2c6b-goog Message-ID: <20240123221749.793069-2-almasrymina@google.com> Subject: [PATCH net-next v6 1/2] net: introduce abstraction for network memory From: Mina Almasry To: linux-kernel@vger.kernel.org, netdev@vger.kernel.org Cc: Mina Almasry , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Jason Gunthorpe , " =?utf-8?q?Christian_K=C3=B6nig?= " , Shakeel Butt , Yunsheng Lin , Willem de Bruijn X-Patchwork-Delegate: kuba@kernel.org Add the netmem_ref type, an abstraction for network memory. To add support for new memory types to the net stack, we must first abstract the current memory type. Currently parts of the net stack use struct page directly: - page_pool - drivers - skb_frag_t Originally the plan was to reuse struct page* for the new memory types, and to set the LSB on the page* to indicate it's not really a page. However, for compiler type checking we need to introduce a new type. netmem_ref is introduced to abstract the underlying memory type. Currently it's a no-op abstraction that is always a struct page underneath. In parallel there is an undergoing effort to add support for devmem to the net stack: https://lore.kernel.org/netdev/20231208005250.2910004-1-almasrymina@google.com/ netmem_ref can be pointers to different underlying memory types, and the low bits are set to indicate the memory type. Helpers are provided to convert netmem pointers to the underlying memory type (currently only struct page). In the devmem series helpers are provided so that calling code can use netmem without worrying about the underlying memory type unless absolutely necessary. Reviewed-by: Shakeel Butt Signed-off-by: Mina Almasry --- v6: - Applied Reviewed-by from Shakeel. rfc v5: - RFC due to merge window. - Change to 'typedef unsigned long __bitwise netmem_ref;' - Fixed commit message (Shakeel). - Did not apply Shakeel's reviewed-by since the code changed significantly. v4: - use 'struct netmem;' instead of 'typedef void *__bitwise netmem_ref;' Using __bitwise with a non-integer type was wrong and triggered many patchwork bot errors/warnings. Using an integer type causes the compiler to warn when casting NULL to the integer type. Attempt to use an empty struct for our opaque network memory. v3: - Modify struct netmem from a union of struct page + new types to an opaque netmem_ref type. I went with: +typedef void *__bitwise netmem_ref; rather than this that Jakub recommended: +typedef unsigned long __bitwise netmem_ref; Because with the latter the compiler issues warnings to cast NULL to netmem_ref. I hope that's ok. - Add some function docs. v2: - Use container_of instead of a type cast (David). --- include/net/netmem.h | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) create mode 100644 include/net/netmem.h diff --git a/include/net/netmem.h b/include/net/netmem.h new file mode 100644 index 000000000000..9f327d964782 --- /dev/null +++ b/include/net/netmem.h @@ -0,0 +1,41 @@ +/* SPDX-License-Identifier: GPL-2.0 + * + * Network memory + * + * Author: Mina Almasry + */ + +#ifndef _NET_NETMEM_H +#define _NET_NETMEM_H + +/** + * netmem_ref - a nonexistent type marking a reference to generic network + * memory. + * + * A netmem_ref currently is always a reference to a struct page. This + * abstraction is introduced so support for new memory types can be added. + * + * Use the supplied helpers to obtain the underlying memory pointer and fields. + */ +typedef unsigned long __bitwise netmem_ref; + +/* This conversion fails (returns NULL) if the netmem_ref is not struct page + * backed. + * + * Currently struct page is the only possible netmem, and this helper never + * fails. + */ +static inline struct page *netmem_to_page(netmem_ref netmem) +{ + return (__force struct page *)netmem; +} + +/* Converting from page to netmem is always safe, because a page can always be + * a netmem. + */ +static inline netmem_ref page_to_netmem(struct page *page) +{ + return (__force netmem_ref)page; +} + +#endif /* _NET_NETMEM_H */