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Date: Wed, 11 Mar 2020 13:28:33 +0200
From: Ido Schimmel <idosch@mellanox.com>
Subject: Re: [PATCH] net: drop_monitor: use IS_REACHABLE() to guard
 net_dm_hw_report()
Message-ID: <20200311112833.GA284417@splinter>
References: <20200311062925.5163-1-masahiroy@kernel.org>
 <20200311093143.GB279080@splinter>
 <20200311104756.GA1972672@hmswarspite.think-freely.org>
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To: Neil Horman <nhorman@tuxdriver.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>, jiri@mellanox.com, 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

On Wed, Mar 11, 2020 at 06:47:56AM -0400, Neil Horman wrote:
> On Wed, Mar 11, 2020 at 11:31:43AM +0200, Ido Schimmel wrote:
> > 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?
> > 
> Agreed, I think I like this implementation better.

OK, but I don't want to block Masahiro. I think we can go with his patch
and then I'll add the raw tracepoint in the next release.