From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 91E7CC433DF for ; Wed, 8 Jul 2020 14:07:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 612DA20720 for ; Wed, 8 Jul 2020 14:07:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="lqW4PIqW" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729650AbgGHOG7 (ORCPT ); Wed, 8 Jul 2020 10:06:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46802 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729493AbgGHOG6 (ORCPT ); Wed, 8 Jul 2020 10:06:58 -0400 Received: from mail-wr1-x442.google.com (mail-wr1-x442.google.com [IPv6:2a00:1450:4864:20::442]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2DA15C061A0B; Wed, 8 Jul 2020 07:06:58 -0700 (PDT) Received: by mail-wr1-x442.google.com with SMTP id o11so49199748wrv.9; Wed, 08 Jul 2020 07:06:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=c0RpjaCUMUz6o0HkW/J+nFuyyVve1i61JY9VJVht368=; b=lqW4PIqWfQiWwKnz+W2eTaeQPRyW1yJbvTZi9pJ0M3CEC6b8DhDd4ue1MyrIy0Cs/l MnGklkRXGkKz3LU3+Cv662jtLDcfKROCrMFS4F+UFBwEUzjYKt7IMK+CUZeC08C0KVp6 H2MXZR8CwFQPSRealaknGKIQKxnO//Ttu3XlaZfrnE8bWa2/UkzBrkVz5Ado1JA1zn9p 0vLwaRWf0PaKnZ7eOjmwcTa/rIrydyFJQpJ1JuMCU/etujF87ccZzRLYmv5SFRwFTX/t QaIbmsuy5Y+ixWPx3kY6JozgDWVxuvhEzJr/5ifzIadgu4ssoZmrerZ5N+fuWiJJeCyp gPeQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=c0RpjaCUMUz6o0HkW/J+nFuyyVve1i61JY9VJVht368=; b=mLU08oI6zFUpfzs0X42roqVel+8esZ25IOnwKOOJrR4iUGut+k9OOP10A8n+cqaCQY OWo1KjatjLmW7ho+7zAl/Nc5JaNJX/k7hQjS3zAT3nPpczlJUytNkEIFzYwyNKrJiTCT eHc+PfZJzwgrpVEzms1weWAruA9YIJeRUBh9yqInj63AiKCDZzwlMtKCXWowJAYcZlsZ pl2luQEiJCgdLu9jTcAHKZf8QWwSK4OTrgERrKDq58A1TtVS4bqFEpAIOPpcccsO8MO6 fLzTOxTCtDIEK1HCjyK8IvxuIJLbtWs4H4OELh2XakueLLSOyaREkhyPoRj/26Eyfz2p 800w== X-Gm-Message-State: AOAM5320Fa5JQc1KOsiwCImhOxPXsKZ7HJ0V9+t59QmtEK4rjZ69Tk4m DnuW/NCZsLS3sp3yRoAl4CTw3ybSZga+zlUHzHGe79BEtNcm2w== X-Google-Smtp-Source: ABdhPJyc/7gbJobUWolD4EV3jhsiVwVBD24Com3m40psFxhlOMB0QKUDUK1y7dIK52QfjrIU3gQSC3DH6f5AtBte8Y8= X-Received: by 2002:a5d:6846:: with SMTP id o6mr59235183wrw.370.1594217216838; Wed, 08 Jul 2020 07:06:56 -0700 (PDT) MIME-Version: 1.0 References: <20200707171515.110818-1-izabela.bakollari@gmail.com> <647a37da-cd95-b84b-bc76-036a813c00e2@gmail.com> In-Reply-To: <647a37da-cd95-b84b-bc76-036a813c00e2@gmail.com> From: Izabela Bakollari Date: Wed, 8 Jul 2020 16:06:45 +0200 Message-ID: Subject: Re: [PATCH net-next] dropwatch: Support monitoring of dropped frames To: Eric Dumazet Cc: nhorman@tuxdriver.com, davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Eric, Thank you for reviewing my patch. I understand your comments and will be working on correcting what you pointed out. Best, Izabela On Tue, Jul 7, 2020 at 7:52 PM Eric Dumazet wrote: > > > > On 7/7/20 10:15 AM, izabela.bakollari@gmail.com wrote: > > From: Izabela Bakollari > > > > Dropwatch is a utility that monitors dropped frames by having userspace > > record them over the dropwatch protocol over a file. This augument > > allows live monitoring of dropped frames using tools like tcpdump. > > > > With this feature, dropwatch allows two additional commands (start and > > stop interface) which allows the assignment of a net_device to the > > dropwatch protocol. When assinged, dropwatch will clone dropped frames, > > and receive them on the assigned interface, allowing tools like tcpdump > > to monitor for them. > > > > With this feature, create a dummy ethernet interface (ip link add dev > > dummy0 type dummy), assign it to the dropwatch kernel subsystem, by using > > these new commands, and then monitor dropped frames in real time by > > running tcpdump -i dummy0. > > > > Signed-off-by: Izabela Bakollari > > --- > > include/uapi/linux/net_dropmon.h | 3 ++ > > net/core/drop_monitor.c | 79 +++++++++++++++++++++++++++++++- > > 2 files changed, 80 insertions(+), 2 deletions(-) > > > > diff --git a/include/uapi/linux/net_dropmon.h b/include/uapi/linux/net_dropmon.h > > index 67e31f329190..e8e861e03a8a 100644 > > --- a/include/uapi/linux/net_dropmon.h > > +++ b/include/uapi/linux/net_dropmon.h > > @@ -58,6 +58,8 @@ enum { > > NET_DM_CMD_CONFIG_NEW, > > NET_DM_CMD_STATS_GET, > > NET_DM_CMD_STATS_NEW, > > + NET_DM_CMD_START_IFC, > > + NET_DM_CMD_STOP_IFC, > > _NET_DM_CMD_MAX, > > }; > > > > @@ -93,6 +95,7 @@ enum net_dm_attr { > > NET_DM_ATTR_SW_DROPS, /* flag */ > > NET_DM_ATTR_HW_DROPS, /* flag */ > > NET_DM_ATTR_FLOW_ACTION_COOKIE, /* binary */ > > + NET_DM_ATTR_IFNAME, /* string */ > > > > __NET_DM_ATTR_MAX, > > NET_DM_ATTR_MAX = __NET_DM_ATTR_MAX - 1 > > diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c > > index 8e33cec9fc4e..8049bff05abd 100644 > > --- a/net/core/drop_monitor.c > > +++ b/net/core/drop_monitor.c > > @@ -30,6 +30,7 @@ > > #include > > #include > > #include > > +#include > > > > #include > > #include > > @@ -46,6 +47,7 @@ > > */ > > static int trace_state = TRACE_OFF; > > static bool monitor_hw; > > +struct net_device *interface; > > > > /* net_dm_mutex > > * > > @@ -220,9 +222,8 @@ static void trace_drop_common(struct sk_buff *skb, void *location) > > struct per_cpu_dm_data *data; > > unsigned long flags; > > > > - local_irq_save(flags); > > + spin_lock_irqsave(&data->lock, flags); > > data = this_cpu_ptr(&dm_cpu_data); > > - spin_lock(&data->lock); > > dskb = data->skb; > > > > if (!dskb) > > @@ -255,6 +256,12 @@ static void trace_drop_common(struct sk_buff *skb, void *location) > > > > out: > > spin_unlock_irqrestore(&data->lock, flags); > > + > > What protects interface from being changed under us by another thread/cpu ? > > > + if (interface && interface != skb->dev) { > > + skb = skb_clone(skb, GFP_ATOMIC); > > + skb->dev = interface; > > + netif_receive_skb(skb); > > + } > > } > > > > static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location) > > @@ -1315,6 +1322,63 @@ static int net_dm_cmd_trace(struct sk_buff *skb, > > return -EOPNOTSUPP; > > } > > > > +static int net_dm_interface_start(struct net *net, const char *ifname) > > +{ > > + struct net_device *nd; > > + > > + nd = dev_get_by_name(net, ifname); > > + > > + if (nd) { > > + interface = nd; > > If interface was already set, you forgot to dev_put() it. > > > + dev_hold(interface); > > Note that dev_get_by_name() already did a dev_hold() > > > + } else { > > + return -ENODEV; > > + } > > + return 0; > > +} > > + > > +static int net_dm_interface_stop(struct net *net, const char *ifname) > > +{ > > + struct net_device *nd; > > + > > + nd = dev_get_by_name(net, ifname); > > + > > + if (nd) { > > > > > + interface = nd; > > > You probably meant : interface = NULL; ? > > > + dev_put(interface); > > and dev_put(nd); > > > > + } else { > > + return -ENODEV; > > + } > > + return 0; > > +} > > + > > +static int net_dm_cmd_ifc_trace(struct sk_buff *skb, struct genl_info *info) > > +{ > > + struct net *net = sock_net(skb->sk); > > + char ifname[IFNAMSIZ]; > > + int rc; > > + > > + memset(ifname, 0, IFNAMSIZ); > > + nla_strlcpy(ifname, info->attrs[NET_DM_ATTR_IFNAME], IFNAMSIZ - 1); > > + > > + switch (info->genlhdr->cmd) { > > + case NET_DM_CMD_START_IFC: > > + rc = net_dm_interface_start(net, ifname); > > + if (rc) > > + return rc; > > + break; > > + case NET_DM_CMD_STOP_IFC: > > + if (interface) { > > + rc = net_dm_interface_stop(net, interface->ifname); > > + return rc; > > + } else { > > + return -ENODEV; > > + } > > + } > > + > > + return 0; > > +} > > + > > static int net_dm_config_fill(struct sk_buff *msg, struct genl_info *info) > > { > > void *hdr; > > @@ -1543,6 +1607,7 @@ static const struct nla_policy net_dm_nl_policy[NET_DM_ATTR_MAX + 1] = { > > [NET_DM_ATTR_QUEUE_LEN] = { .type = NLA_U32 }, > > [NET_DM_ATTR_SW_DROPS] = {. type = NLA_FLAG }, > > [NET_DM_ATTR_HW_DROPS] = {. type = NLA_FLAG }, > > + [NET_DM_ATTR_IFNAME] = {. type = NLA_STRING, .len = IFNAMSIZ }, > > }; > > > > static const struct genl_ops dropmon_ops[] = { > > @@ -1570,6 +1635,16 @@ static const struct genl_ops dropmon_ops[] = { > > .cmd = NET_DM_CMD_STATS_GET, > > .doit = net_dm_cmd_stats_get, > > }, > > + { > > + .cmd = NET_DM_CMD_START_IFC, > > + .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, > > + .doit = net_dm_cmd_ifc_trace, > > + }, > > + { > > + .cmd = NET_DM_CMD_STOP_IFC, > > + .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, > > + .doit = net_dm_cmd_ifc_trace, > > + }, > > }; > > > > static int net_dm_nl_pre_doit(const struct genl_ops *ops, > >