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Date:   Tue, 13 Sep 2022 10:15:48 +0200
From:   Casper Andersson <casper.casan@gmail.com>
To:     Nathan Huckleberry <nhuck@google.com>
Cc:     Dan Carpenter <error27@gmail.com>, llvm@lists.linux.dev,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Lars Povlsen <lars.povlsen@microchip.com>,
        Steen Hegelund <Steen.Hegelund@microchip.com>,
        UNGLinuxDriver@microchip.com,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>,
        Horatiu Vultur <horatiu.vultur@microchip.com>,
        netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: sparx5: Fix return type of sparx5_port_xmit_impl
Message-ID: <20220913081548.gmngjwuagbt63j7h@wse-c0155>
Organization: Westermo Network Technologies AB
References: <20220912214432.928989-1-nhuck@google.com>
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Hi,

On 2022-09-12 14:44, Nathan Huckleberry wrote:
> The ndo_start_xmit field in net_device_ops is expected to be of type
> netdev_tx_t (*ndo_start_xmit)(struct sk_buff *skb, struct net_device *dev).
> 
> The mismatched return type breaks forward edge kCFI since the underlying
> function definition does not match the function hook definition.
> 
> The return type of sparx5_port_xmit_impl should be changed from int to
> netdev_tx_t.

I noticed that the functions that assign the return value inside
sparx5_port_xmit_impl also have return type int, which would ideally
also be changed. But a bigger issue might be that
sparx5_ptp_txtstamp_request and sparx5_inject (called inside
sparx5_port_xmit_impl) returns -EBUSY (-16), when they should return
NETDEV_TX_BUSY (16). If this is an issue then it also needs to be fixed.

sparx5_fdma_xmit also has int return type, but always returns
NETDEV_TX_OK right now.

Best Regards,
Casper