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Date:   Wed, 11 Mar 2020 11:31:43 +0200
From:   Ido Schimmel <idosch@mellanox.com>
To:     Masahiro Yamada <masahiroy@kernel.org>, nhorman@tuxdriver.com,
        jiri@mellanox.com
Cc:     netdev@vger.kernel.org, "David S . Miller" <davem@davemloft.net>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Nicolas Pitre <nico@fluxnic.net>, linux-kbuild@vger.kernel.org,
        Jakub Kicinski <kuba@kernel.org>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: drop_monitor: use IS_REACHABLE() to guard
 net_dm_hw_report()
Message-ID: <20200311093143.GB279080@splinter>
References: <20200311062925.5163-1-masahiroy@kernel.org>
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On Wed, Mar 11, 2020 at 03:29:25PM +0900, Masahiro Yamada wrote:
> In net/Kconfig, NET_DEVLINK implies NET_DROP_MONITOR.
> 
> The original behavior of the 'imply' keyword prevents NET_DROP_MONITOR
> from being 'm' when NET_DEVLINK=y.
> 
> With the planned Kconfig change that relaxes the 'imply', the
> combination of NET_DEVLINK=y and NET_DROP_MONITOR=m would be allowed.
> 
> Use IS_REACHABLE() to avoid the vmlinux link error for this case.
> 
> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Thanks, Masahiro.

Neil, Jiri, another option (long term) is to add a raw tracepoint (not
part of ABI) in devlink and have drop monitor register its probe on it
when monitoring.

Two advantages:
1. Consistent with what drop monitor is already doing with kfree_skb()
tracepoint
2. We can remove 'imply NET_DROP_MONITOR' altogether

What do you think?