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Message-ID: <ZdYes3iPqzf0FCTf@nanopsycho>
Date: Wed, 21 Feb 2024 17:02:59 +0100
From: Jiri Pirko <jiri@...nulli.us>
To: Eric Dumazet <edumazet@...gle.com>
Cc: "David S . Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
netdev@...r.kernel.org, eric.dumazet@...il.com
Subject: Re: [PATCH net-next 12/13] rtnetlink: make rtnl_fill_link_ifmap()
RCU ready
Wed, Feb 21, 2024 at 11:59:14AM CET, edumazet@...gle.com wrote:
>Use READ_ONCE() to read the following device fields:
>
> dev->mem_start
> dev->mem_end
> dev->base_addr
> dev->irq
> dev->dma
> dev->if_port
>
>Provide IFLA_MAP attribute only if at least one of these fields
>is not zero. This saves some space in the output skb for most devices.
>
>Signed-off-by: Eric Dumazet <edumazet@...gle.com>
>---
> net/core/rtnetlink.c | 26 ++++++++++++++------------
> 1 file changed, 14 insertions(+), 12 deletions(-)
>
>diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
>index 1b26dfa5668d22fb2e30ceefbf143e98df13ae29..b91ec216c593aaebf97ea69aa0d2d265ab61c098 100644
>--- a/net/core/rtnetlink.c
>+++ b/net/core/rtnetlink.c
>@@ -1455,19 +1455,21 @@ static noinline_for_stack int rtnl_fill_vf(struct sk_buff *skb,
> return 0;
> }
>
>-static int rtnl_fill_link_ifmap(struct sk_buff *skb, struct net_device *dev)
>+static int rtnl_fill_link_ifmap(struct sk_buff *skb,
>+ const struct net_device *dev)
> {
> struct rtnl_link_ifmap map;
>
> memset(&map, 0, sizeof(map));
>- map.mem_start = dev->mem_start;
>- map.mem_end = dev->mem_end;
>- map.base_addr = dev->base_addr;
>- map.irq = dev->irq;
>- map.dma = dev->dma;
>- map.port = dev->if_port;
>-
>- if (nla_put_64bit(skb, IFLA_MAP, sizeof(map), &map, IFLA_PAD))
>+ map.mem_start = READ_ONCE(dev->mem_start);
>+ map.mem_end = READ_ONCE(dev->mem_end);
>+ map.base_addr = READ_ONCE(dev->base_addr);
>+ map.irq = READ_ONCE(dev->irq);
>+ map.dma = READ_ONCE(dev->dma);
>+ map.port = READ_ONCE(dev->if_port);
>+ /* Only report non zero information. */
>+ if (memchr_inv(&map, 0, sizeof(map)) &&
This check(optimization) is unrelated to the rest of the patch, correct?
If yes, could it be a separate patch?
>+ nla_put_64bit(skb, IFLA_MAP, sizeof(map), &map, IFLA_PAD))
> return -EMSGSIZE;
>
> return 0;
>@@ -1875,9 +1877,6 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb,
> goto nla_put_failure;
> }
>
>- if (rtnl_fill_link_ifmap(skb, dev))
>- goto nla_put_failure;
>-
> if (dev->addr_len) {
> if (nla_put(skb, IFLA_ADDRESS, dev->addr_len, dev->dev_addr) ||
> nla_put(skb, IFLA_BROADCAST, dev->addr_len, dev->broadcast))
>@@ -1927,6 +1926,9 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb,
> rcu_read_lock();
> if (rtnl_fill_link_af(skb, dev, ext_filter_mask))
> goto nla_put_failure_rcu;
>+ if (rtnl_fill_link_ifmap(skb, dev))
>+ goto nla_put_failure_rcu;
>+
> rcu_read_unlock();
>
> if (rtnl_fill_prop_list(skb, dev))
>--
>2.44.0.rc0.258.g7320e95886-goog
>
>
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