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Date: Wed, 4 Oct 2023 16:16:51 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: <edward.cree@amd.com>
Cc: <linux-net-drivers@amd.com>, <davem@davemloft.net>,
 <edumazet@google.com>, <pabeni@redhat.com>, Edward Cree
 <ecree.xilinx@gmail.com>, <netdev@vger.kernel.org>,
 <habetsm.xilinx@gmail.com>, <sudheer.mogilappagari@intel.com>,
 <jdamato@fastly.com>, <andrew@lunn.ch>, <mw@semihalf.com>,
 <linux@armlinux.org.uk>, <sgoutham@marvell.com>, <gakula@marvell.com>,
 <sbhatta@marvell.com>, <hkelam@marvell.com>, <saeedm@nvidia.com>,
 <leon@kernel.org>
Subject: Re: [PATCH v4 net-next 6/7] net: ethtool: add a mutex protecting
 RSS contexts
Message-ID: <20231004161651.76f686f3@kernel.org>
In-Reply-To: <b5d7b8e243178d63643c8efc1f1c48b3b2468dc7.1695838185.git.ecree.xilinx@gmail.com>
References: <cover.1695838185.git.ecree.xilinx@gmail.com>
	<b5d7b8e243178d63643c8efc1f1c48b3b2468dc7.1695838185.git.ecree.xilinx@gmail.com>
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On Wed, 27 Sep 2023 19:13:37 +0100 edward.cree@amd.com wrote:
> While this is not needed to serialise the ethtool entry points (which
>  are all under RTNL), drivers may have cause to asynchronously access
>  dev->ethtool->rss_ctx; taking dev->ethtool->rss_lock allows them to
>  do this safely without needing to take the RTNL.

Can we use a replay mechanism, like we do in TC offloads and VxLAN/UDP
ports? The driver which lost config can ask for the rss contexts to be
"replayed" and the core will issue a series of ->create calls for all
existing entries?

Regarding the lock itself - can we hide it under ethtool_rss_lock(dev)
/ ethtool_rss_unlock(dev) helpers?