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Date:   Thu, 18 Nov 2021 17:48:13 -0800
From:   Jakub Kicinski <kuba@kernel.org>
To:     Leon Romanovsky <leon@kernel.org>
Cc:     "David S . Miller" <davem@davemloft.net>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Andrew Lunn <andrew@lunn.ch>, Aya Levin <ayal@mellanox.com>,
        Claudiu Manoil <claudiu.manoil@nxp.com>, drivers@pensando.io,
        Florian Fainelli <f.fainelli@gmail.com>,
        Ido Schimmel <idosch@nvidia.com>,
        intel-wired-lan@lists.osuosl.org,
        Ioana Ciornei <ioana.ciornei@nxp.com>,
        Jesse Brandeburg <jesse.brandeburg@intel.com>,
        Jiri Pirko <jiri@nvidia.com>, linux-kernel@vger.kernel.org,
        linux-rdma@vger.kernel.org,
        Michael Chan <michael.chan@broadcom.com>,
        netdev@vger.kernel.org, oss-drivers@corigine.com,
        Saeed Mahameed <saeedm@nvidia.com>,
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        Simon Horman <simon.horman@corigine.com>,
        Taras Chornyi <tchornyi@marvell.com>,
        Tariq Toukan <tariqt@nvidia.com>,
        Tony Nguyen <anthony.l.nguyen@intel.com>,
        UNGLinuxDriver@microchip.com,
        Vivien Didelot <vivien.didelot@gmail.com>,
        Vladimir Oltean <vladimir.oltean@nxp.com>
Subject: Re: [PATCH net-next 5/6] devlink: Reshuffle resource registration
 logic
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On Thu, 18 Nov 2021 09:50:20 +0200 Leon Romanovsky wrote:
> And it shouldn't. devlink_resource_find() will return valid resource only
> if there driver is completely bogus with races or incorrect allocations of
> resource_id.
> 
> devlink_*_register(..)
>  mutex_lock(&devlink->lock);
>  if (devlink_*_find(...)) {
>     mutex_unlock(&devlink->lock);
>     return ....;
>  }
>  .....
> 
> It is almost always wrong from locking and layering perspective the pattern above,
> as it is racy by definition if not protected by top layer.
> 
> There are exceptions from the rule above, but devlink is clearly not the
> one of such exceptions.

Just drop the unnecessary "cleanup" patches and limit the amount 
of driver code we'll have to revert if your approach fails.

I spent enough time going back and forth with you.

Please.