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Message-ID: <ef9d4ca5-35e4-ff8c-c1aa-f77a4b04d0a2@intel.com>
Date: Thu, 14 Sep 2023 17:22:00 +0200
From: Alexander Lobakin <aleksander.lobakin@...el.com>
To: Yajun Deng <yajun.deng@...ux.dev>
CC: <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
<pabeni@...hat.com>, <horms@...nel.org>, <netdev@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next v3] net/core: Export dev_core_stats_*_inc()
From: Yajun Deng <yajun.deng@...ux.dev>
Date: Thu, 14 Sep 2023 10:37:18 +0800
> Although there is a kfree_skb_reason() helper function that can be used to
> find the reason why this skb is dropped, but most callers didn't increase
> one of rx_dropped, tx_dropped, rx_nohandler and rx_otherhost_dropped.
>
> For the users, people are more concerned about why the dropped in ip
> is increasing. So we can export dev_core_stats_rx_dropped_inc sets,
> which users would trace them know why rx_dropped is increasing.
>
> Export dev_core_stats_{rx_dropped, tx_dropped, rx_nohandler,
> rx_otherhost_dropped}_inc for trace. Also, move dev_core_stats()
> and netdev_core_stats_alloc() to dev.c, as they are not called
> externally.
I'd like to hear some arguments against having them static inlines + one
external that I proposed earlier.
>
> Signed-off-by: Yajun Deng <yajun.deng@...ux.dev>
> ---
> v3: __cold should be added to the netdev_core_stats_alloc().
> v2: use __cold instead of inline in dev_core_stats().
> v1: https://lore.kernel.org/netdev/20230911082016.3694700-1-yajun.deng@linux.dev/
...as it's not at least mentioned here in the changelog.
[...]
> diff --git a/net/core/dev.c b/net/core/dev.c
> index ccff2b6ef958..98592e4c1df0 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -10475,7 +10475,7 @@ void netdev_stats_to_stats64(struct rtnl_link_stats64 *stats64,
> }
> EXPORT_SYMBOL(netdev_stats_to_stats64);
>
> -struct net_device_core_stats __percpu *netdev_core_stats_alloc(struct net_device *dev)
> +static __cold struct net_device_core_stats __percpu *netdev_core_stats_alloc(struct net_device *dev)
This is way over 79/80 chars, break the line before "netdev_".
> {
> struct net_device_core_stats __percpu *p;
>
> @@ -10488,7 +10488,35 @@ struct net_device_core_stats __percpu *netdev_core_stats_alloc(struct net_device
> /* This READ_ONCE() pairs with the cmpxchg() above */
> return READ_ONCE(dev->core_stats);
> }
> -EXPORT_SYMBOL(netdev_core_stats_alloc);
> +
> +static inline struct net_device_core_stats __percpu *dev_core_stats(struct net_device *dev)
Same for the line length.
Also notice that now some of the functions you touch have "dev_" prefix,
others have "netdev_", I'd probably take a look into unifying this.
(note for the maintainers that it would be probably better to leave
explicit "inline" here, but no bloat-o-meter was provided by the
author, so I can't say anything for sure)
> +{
> + /* This READ_ONCE() pairs with the write in netdev_core_stats_alloc() */
> + struct net_device_core_stats __percpu *p = READ_ONCE(dev->core_stats);
> +
> + if (likely(p))
> + return p;
> +
> + return netdev_core_stats_alloc(dev);
> +}
[...]
Thanks,
Olek
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