Subject: Re: [PATCH] sfc: use IS_ENABLED() checks for CONFIG_SFC_SRIOV
To:     Arnd Bergmann <arnd@kernel.org>,
        Martin Habets <habetsm.xilinx@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Alejandro Lucero <alejandro.lucero-palau@amd.com>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Jonathan Cooper <jonathan.s.cooper@amd.com>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Leon Romanovsky <leon@kernel.org>
References: <20230217095650.2305559-1-arnd@kernel.org>
From:   Edward Cree <ecree.xilinx@gmail.com>
Message-ID: <f38d6b22-f846-5637-d58b-2d8862bc6840@gmail.com>
Date:   Fri, 17 Feb 2023 16:13:59 +0000
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.14.0
MIME-Version: 1.0
In-Reply-To: <20230217095650.2305559-1-arnd@kernel.org>
Content-Type: text/plain; charset=utf-8
Content-Language: en-GB
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 17/02/2023 09:56, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> One local variable has become unused after a recent change:
> 
> drivers/net/ethernet/sfc/ef100_nic.c: In function 'ef100_probe_netdev_pf':
> drivers/net/ethernet/sfc/ef100_nic.c:1155:21: error: unused variable 'net_dev' [-Werror=unused-variable]
>   struct net_device *net_dev = efx->net_dev;
>                      ^~~~~~~
> 
> The variable is still used in an #ifdef. Replace the #ifdef with
> an if(IS_ENABLED()) check that lets the compiler see where it is
> used, rather than adding another #ifdef.

So we've had Leon telling us[1] to use __maybe_unused, and you're
 saying to use IS_ENABLED() instead.  Which is right?
(And does it make any difference to build time?  I'm assuming the
 compiler is smart enough that this change doesn't affect text
 size...?)
-ed

[1]: https://lore.kernel.org/netdev/cac3fa89-50a3-6de0-796c-a215400f3710@intel.com/T/#md2ecc82f18c200391dc6581ff68ff08eee9a65cf