From patchwork Wed Oct 30 16:51:54 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Lobakin X-Patchwork-Id: 13856878 X-Patchwork-Delegate: kuba@kernel.org Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CD2072296F5; Wed, 30 Oct 2024 16:54:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.10 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730307257; cv=none; b=rPqxz6T4DAhGToePza3L3QLUazqsMjdI9yOWT6eDCObEqMncrWvTtVl8SLDGLh5ROONKyKTEPsLkczTZZFyKMnYR2ervmpCtw5o6bI/olHjlj7JdO/Dc6l+vxzx7RSTuIOjYyX2xKQydWQVbFw8zPjUzweiql4RDl7bM4QiFV5I= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730307257; c=relaxed/simple; bh=DXKV5tHRVERPeEsblP/yRrq3CP6BqLAgt7hogDsb0wQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jNQixfbbcbAuAcIsTT2df3zzIQAH/XOK+RBfnkOZN23yyD4czik3ZoqVPGVlQ3wywoYmYZEYcd1xZ7keKsltZHy1Sa3O69wMSJWD3pj1YhT0Xk7GLMRKFbDPqtzEe7/d4o+Y9WTYzgDJ+IyK/ShfSRG+mxFo3bb1BumKq9gkKxs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Z3NZVkad; arc=none smtp.client-ip=192.198.163.10 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Z3NZVkad" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1730307255; x=1761843255; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=DXKV5tHRVERPeEsblP/yRrq3CP6BqLAgt7hogDsb0wQ=; b=Z3NZVkad9oFjvEKtu9U4M76cylizYxnSaqMWI5OLMMrmrAPELPK7Mimr G3ezBQwGAiWxsVcJr8E2yD5Yscb1O6gMkfl+1ATxeJNLy7dLcpSNO5OYb BpH/8ly7w5XzCLk7GwdD6h/SzRwMbelHm73p9EUMCABoeJsrBpuZe8kS+ NB3hy71XP0Tjg/r85e1SvEXOR5ioT4O62WLinajlZAU3AXnrPf/mL+hxt wVtJnwp34mzcirppBfbE1OD4ohVhyaT4Kc709pW51N2nmNKD8IZU2tJq3 VKzDooftfKaiplk+gXYgm6BueHercp+oxvZqUzEIU3XxIod1buRYH9gID A==; X-CSE-ConnectionGUID: WPG6WRi/SZ2X+cFvUWw1Yw== X-CSE-MsgGUID: 8fIO26XzRN2HmoP5NK8lTg== X-IronPort-AV: E=McAfee;i="6700,10204,11241"; a="41389776" X-IronPort-AV: E=Sophos;i="6.11,245,1725346800"; d="scan'208";a="41389776" Received: from orviesa004.jf.intel.com ([10.64.159.144]) by fmvoesa104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Oct 2024 09:54:15 -0700 X-CSE-ConnectionGUID: hR28saU+SueVV0sGawFcpA== X-CSE-MsgGUID: GOOt05PJTsGNbB7T0d5Cjg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.11,245,1725346800"; d="scan'208";a="87524519" Received: from newjersey.igk.intel.com ([10.102.20.203]) by orviesa004.jf.intel.com with ESMTP; 30 Oct 2024 09:54:11 -0700 From: Alexander Lobakin To: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Alexander Lobakin , =?utf-8?q?Toke_H=C3=B8?= =?utf-8?q?iland-J=C3=B8rgensen?= , Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Maciej Fijalkowski , Stanislav Fomichev , Magnus Karlsson , nex.sw.ncis.osdt.itp.upstreaming@intel.com, bpf@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH net-next v3 11/18] xdp: add generic xdp_buff_add_frag() Date: Wed, 30 Oct 2024 17:51:54 +0100 Message-ID: <20241030165201.442301-12-aleksander.lobakin@intel.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241030165201.442301-1-aleksander.lobakin@intel.com> References: <20241030165201.442301-1-aleksander.lobakin@intel.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org The code piece which would attach a frag to &xdp_buff is almost identical across the drivers supporting XDP multi-buffer on Rx. Make it a generic elegant "oneliner". Also, I see lots of drivers calculating frags_truesize as `xdp->frame_sz * nr_frags`. I can't say this is fully correct, since frags might be backed by chunks of different sizes, especially with stuff like the header split. Even page_pool_alloc() can give you two different truesizes on two subsequent requests to allocate the same buffer size. Add a field to &skb_shared_info (unionized as there's no free slot currently on x86_64) to track the "true" truesize. It can be used later when updating an skb. Reviewed-by: Maciej Fijalkowski Signed-off-by: Alexander Lobakin --- include/linux/skbuff.h | 16 ++++++-- include/net/xdp.h | 90 +++++++++++++++++++++++++++++++++++++++++- 2 files changed, 101 insertions(+), 5 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index c867df5b1051..6ec78c1598fe 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -607,11 +607,19 @@ struct skb_shared_info { * Warning : all fields before dataref are cleared in __alloc_skb() */ atomic_t dataref; - unsigned int xdp_frags_size; - /* Intermediate layers must ensure that destructor_arg - * remains valid until skb destructor */ - void * destructor_arg; + union { + struct { + u32 xdp_frags_size; + u32 xdp_frags_truesize; + }; + + /* + * Intermediate layers must ensure that destructor_arg + * remains valid until skb destructor. + */ + void *destructor_arg; + }; /* must be last field, see pskb_expand_head() */ skb_frag_t frags[MAX_SKB_FRAGS]; diff --git a/include/net/xdp.h b/include/net/xdp.h index c4b408d22669..19d2b283b845 100644 --- a/include/net/xdp.h +++ b/include/net/xdp.h @@ -167,6 +167,88 @@ xdp_get_buff_len(const struct xdp_buff *xdp) return len; } +/** + * __xdp_buff_add_frag - attach a frag to an &xdp_buff + * @xdp: XDP buffer to attach the frag to + * @page: page containing the frag + * @offset: page offset at which the frag starts + * @size: size of the frag + * @truesize: truesize (page / page frag size) of the frag + * @try_coalesce: whether to try coalescing the frags + * + * Attach a frag to an XDP buffer. If it currently has no frags attached, + * initialize the related fields, otherwise check that the frag number + * didn't reach the limit of ``MAX_SKB_FRAGS``. If possible, try coalescing + * the frag with the previous one. + * The function doesn't check/update the pfmemalloc bit. Please use the + * non-underscored wrapper in drivers. + * + * Return: true on success, false if there's no space for the frag in + * the shared info struct. + */ +static inline bool __xdp_buff_add_frag(struct xdp_buff *xdp, struct page *page, + u32 offset, u32 size, u32 truesize, + bool try_coalesce) +{ + struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp); + skb_frag_t *prev; + u32 nr_frags; + + if (!xdp_buff_has_frags(xdp)) { + xdp_buff_set_frags_flag(xdp); + + nr_frags = 0; + sinfo->xdp_frags_size = 0; + sinfo->xdp_frags_truesize = 0; + + goto fill; + } + + nr_frags = sinfo->nr_frags; + if (unlikely(nr_frags == MAX_SKB_FRAGS)) + return false; + + prev = &sinfo->frags[nr_frags - 1]; + if (try_coalesce && page == skb_frag_page(prev) && + offset == skb_frag_off(prev) + skb_frag_size(prev)) + skb_frag_size_add(prev, size); + else +fill: + __skb_fill_page_desc_noacc(sinfo, nr_frags++, page, + offset, size); + + sinfo->nr_frags = nr_frags; + sinfo->xdp_frags_size += size; + sinfo->xdp_frags_truesize += truesize; + + return true; +} + +/** + * xdp_buff_add_frag - attach a frag to an &xdp_buff + * @xdp: XDP buffer to attach the frag to + * @page: page containing the frag + * @offset: page offset at which the frag starts + * @size: size of the frag + * @truesize: truesize (page / page frag size) of the frag + * + * Version of __xdp_buff_add_frag() which takes care of the pfmemalloc bit. + * + * Return: true on success, false if there's no space for the frag in + * the shared info struct. + */ +static inline bool xdp_buff_add_frag(struct xdp_buff *xdp, struct page *page, + u32 offset, u32 size, u32 truesize) +{ + if (!__xdp_buff_add_frag(xdp, page, offset, size, truesize, true)) + return false; + + if (unlikely(page_is_pfmemalloc(page))) + xdp_buff_set_frag_pfmemalloc(xdp); + + return true; +} + struct xdp_frame { void *data; u32 len; @@ -230,7 +312,13 @@ xdp_update_skb_shared_info(struct sk_buff *skb, u8 nr_frags, unsigned int size, unsigned int truesize, bool pfmemalloc) { - skb_shinfo(skb)->nr_frags = nr_frags; + struct skb_shared_info *sinfo = skb_shinfo(skb); + + sinfo->nr_frags = nr_frags; + /* ``destructor_arg`` is unionized with ``xdp_frags_{,true}size``, + * reset it after that these fields aren't used anymore. + */ + sinfo->destructor_arg = NULL; skb->len += size; skb->data_len += size;