From patchwork Wed Aug 16 10:24:44 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Eric Dumazet X-Patchwork-Id: 801976 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="dvguky/e"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3xXQT92RNhz9t42 for ; Wed, 16 Aug 2017 20:25:01 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751861AbdHPKYt (ORCPT ); Wed, 16 Aug 2017 06:24:49 -0400 Received: from mail-io0-f195.google.com ([209.85.223.195]:38736 "EHLO mail-io0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751841AbdHPKYr (ORCPT ); Wed, 16 Aug 2017 06:24:47 -0400 Received: by mail-io0-f195.google.com with SMTP id o9so2050799iod.5; Wed, 16 Aug 2017 03:24:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=message-id:subject:from:to:cc:date:in-reply-to:references :mime-version:content-transfer-encoding; bh=LvQPfekDGgi6UkuwIMRL3E7rVS9dUdIpWKxE2uivNvc=; b=dvguky/eW52ru4cekQgnEYPqK0kKGAELrB7gHsY5NN2Nynz3v5grAszuvWIgILD4xC l9HHiW9INOmnXoE3+1TtxOxNSiu2L1lfH+X5GLrJKz8rTo40UVKqHV2pS6/mtr35ovOy gVGqrUz3/qx2JS3S329pRJYab86mK1yJQVEKJ4DKsQVgmG/ZKb6Wh66eB7kvNPU7UitS MdHjZemVIMtisBOFXpisYoDTst2bjPh8DTawYFr/9l9dG3rh9G/deX4UHGkaliAdoFbY 1HN8Kq1uKwXLoR3jYQ7TGCLjUZEaVwwgaZYcA0yJXlv9EyYRilS00eTwttv17qdT0jgR yyCw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to :references:mime-version:content-transfer-encoding; bh=LvQPfekDGgi6UkuwIMRL3E7rVS9dUdIpWKxE2uivNvc=; b=COg9VEIrtjrpWcGXCHfBWvgS2foLS4/wR2W/ewgB2G2CKRm0Qh/kNuWOlWAkTNEDQm XaBsjwMGqHkL5d7JDoSKxJT0zF8FIlvBa8PNaCRQrIUQL9Ht7J3KAmaKvcHAbqpbDwLk b0hTTmHz28MUD5/YH4BeRhubvDKN4cUqIQjIfAuLgt/a627sz0YPFlh4Cpuabb17SAAK OgMME789VN4Fabbyg2652FDIC9P1UP0R4+0j9RP6l0iNGNkQKdVYzsa7gM3Ws3pe8yxu XuJT7hQUWG+Nn+TSOikWZ3mkz18qqld3iAN1T3rZxxUier7ra6W0XfpN6TUR1HBHXmfg +oBA== X-Gm-Message-State: AHYfb5iX+Wws6G0Fn+PKU6LouDUeQp/5OX9wyqaN0hhR9/DP6QvJWfr4 wtsX5OhVCSP6Tw== X-Received: by 10.107.19.38 with SMTP id b38mr903878ioj.285.1502879086936; Wed, 16 Aug 2017 03:24:46 -0700 (PDT) Received: from [192.168.86.171] (c-67-180-167-114.hsd1.ca.comcast.net. [67.180.167.114]) by smtp.googlemail.com with ESMTPSA id p194sm351308itp.12.2017.08.16.03.24.45 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 16 Aug 2017 03:24:46 -0700 (PDT) Message-ID: <1502879084.4936.95.camel@edumazet-glaptop3.roam.corp.google.com> Subject: Re: [PATCH net-next V2 1/3] tap: use build_skb() for small packet From: Eric Dumazet To: Jason Wang Cc: davem@davemloft.net, mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kubakici@wp.pl Date: Wed, 16 Aug 2017 03:24:44 -0700 In-Reply-To: <2ae570ab-01da-2ea2-0549-3e310158b817@redhat.com> References: <1502451678-17358-1-git-send-email-jasowang@redhat.com> <1502451678-17358-2-git-send-email-jasowang@redhat.com> <1502855120.4936.89.camel@edumazet-glaptop3.roam.corp.google.com> <2ae570ab-01da-2ea2-0549-3e310158b817@redhat.com> X-Mailer: Evolution 3.10.4-0ubuntu2 Mime-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, 2017-08-16 at 11:55 +0800, Jason Wang wrote: > > On 2017年08月16日 11:45, Eric Dumazet wrote: > > > > You do realize that tun_build_skb() is not thread safe ? > > Ok, I think the issue if skb_page_frag_refill(), need a spinlock > probably. Will prepare a patch. But since tun is used from process context, why don't you use the per-thread generator (no lock involved) tcp_sendmsg() uses this for GFP_KERNEL allocations. Untested patch : Tested-by: Jason Wang Acked-by: Jason Wang diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 5892284eb8d05b0678d820bad3d0d2c61a879aeb..c38cd840cc0b7fecf182b23976e36f709cacca1f 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -175,7 +175,6 @@ struct tun_file { struct list_head next; struct tun_struct *detached; struct skb_array tx_array; - struct page_frag alloc_frag; }; struct tun_flow_entry { @@ -578,8 +577,6 @@ static void __tun_detach(struct tun_file *tfile, bool clean) } if (tun) skb_array_cleanup(&tfile->tx_array); - if (tfile->alloc_frag.page) - put_page(tfile->alloc_frag.page); sock_put(&tfile->sk); } } @@ -1272,7 +1269,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, struct virtio_net_hdr *hdr, int len, int *generic_xdp) { - struct page_frag *alloc_frag = &tfile->alloc_frag; + struct page_frag *alloc_frag = ¤t->task_frag; struct sk_buff *skb; struct bpf_prog *xdp_prog; int buflen = SKB_DATA_ALIGN(len + TUN_RX_PAD) + @@ -2580,8 +2577,6 @@ static int tun_chr_open(struct inode *inode, struct file * file) tfile->sk.sk_write_space = tun_sock_write_space; tfile->sk.sk_sndbuf = INT_MAX; - tfile->alloc_frag.page = NULL; - file->private_data = tfile; INIT_LIST_HEAD(&tfile->next);