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[146.241.77.210]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3997f9a3f6bsm2830317f8f.39.2025.03.21.09.31.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 21 Mar 2025 09:31:19 -0700 (PDT) Message-ID: Date: Fri, 21 Mar 2025 17:31:17 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v3 1/7] net: ethtool: netlink: Allow per-netdevice DUMP operations To: Maxime Chevallier , davem@davemloft.net, Andrew Lunn , Jakub Kicinski , Eric Dumazet , Heiner Kallweit Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, thomas.petazzoni@bootlin.com, linux-arm-kernel@lists.infradead.org, Christophe Leroy , Herve Codina , Florian Fainelli , Russell King , Vladimir Oltean , =?UTF-8?Q?K=C3=B6ry_Maincent?= , Oleksij Rempel , Simon Horman , Romain Gantois , Piergiorgio Beruto References: <20250313182647.250007-1-maxime.chevallier@bootlin.com> <20250313182647.250007-2-maxime.chevallier@bootlin.com> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20250313182647.250007-2-maxime.chevallier@bootlin.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/13/25 7:26 PM, Maxime Chevallier wrote: > We have a number of netlink commands in the ethnl family that may have > multiple objects to dump even for a single net_device, including : > > - PLCA, PSE-PD, phy: one message per PHY device > - tsinfo: one message per timestamp source (netdev + phys) > - rss: One per RSS context > > To get this behaviour, these netlink commands need to roll a custom > ->dumpit(). > > To prepare making per-netdev DUMP more generic in ethnl, introduce a > member in the ethnl ops to indicate if a given command may allow > pernetdev DUMPs (also referred to as filtered DUMPs). > > Signed-off-by: Maxime Chevallier > --- > net/ethtool/netlink.c | 45 +++++++++++++++++++++++++++++-------------- > net/ethtool/netlink.h | 2 ++ > 2 files changed, 33 insertions(+), 14 deletions(-) > > diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c > index a163d40c6431..7adede5e4ff1 100644 > --- a/net/ethtool/netlink.c > +++ b/net/ethtool/netlink.c > @@ -587,21 +587,38 @@ static int ethnl_default_dumpit(struct sk_buff *skb, > int ret = 0; > > rcu_read_lock(); Maintain the RCU read lock here is IMHO confusing... > - for_each_netdev_dump(net, dev, ctx->pos_ifindex) { > - dev_hold(dev); > + if (ctx->req_info->dev) { > + dev = ctx->req_info->dev; .. as this is refcounted. I suggest to move the rcu_read_lock inside the if. > rcu_read_unlock(); > + /* Filtered DUMP request targeted to a single netdev. We already > + * hold a ref to the netdev from ->start() > + */ > + ret = ethnl_default_dump_one(skb, dev, ctx, > + genl_info_dump(cb)); > + rcu_read_lock(); > + netdev_put(ctx->req_info->dev, &ctx->req_info->dev_tracker); > > - ret = ethnl_default_dump_one(skb, dev, ctx, genl_info_dump(cb)); > + if (ret < 0 && ret != -EOPNOTSUPP && likely(skb->len)) > + ret = skb->len; > > - rcu_read_lock(); > - dev_put(dev); > + } else { > + for_each_netdev_dump(net, dev, ctx->pos_ifindex) { > + dev_hold(dev); > + rcu_read_unlock(); > + > + ret = ethnl_default_dump_one(skb, dev, ctx, > + genl_info_dump(cb)); > + > + rcu_read_lock(); > + dev_put(dev); > > - if (ret < 0 && ret != -EOPNOTSUPP) { > - if (likely(skb->len)) > - ret = skb->len; > - break; > + if (ret < 0 && ret != -EOPNOTSUPP) { > + if (likely(skb->len)) > + ret = skb->len; IMHO a bit too many levels of indentation. It's possibly better to move this code in a separate helper. Thanks, Paolo