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Date:   Tue, 13 Sep 2022 16:12:39 -0700
From:   Nathan Chancellor <nathan@kernel.org>
To:     Nathan Huckleberry <nhuck@google.com>
Cc:     Dan Carpenter <error27@gmail.com>, llvm@lists.linux.dev,
        Larry Finger <Larry.Finger@lwfinger.net>,
        Florian Schilhabel <florian.c.schilhabel@googlemail.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>,
        Sathish Kumar <skumark1902@gmail.com>,
        "Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
        linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] staging: rtl8712: Fix return type of r8712_xmit_entry
Message-ID: <YyEOZ+u/T8rP6o9S@dev-arch.thelio-3990X>
References: <20220912214607.929211-1-nhuck@google.com>
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On Mon, Sep 12, 2022 at 02:46:03PM -0700, 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 r8712_xmit_entry should be changed from int to
> netdev_tx_t.
> 
> Reported-by: Dan Carpenter <error27@gmail.com>
> Link: https://github.com/ClangBuiltLinux/linux/issues/1703
> Cc: llvm@lists.linux.dev
> Signed-off-by: Nathan Huckleberry <nhuck@google.com>

The prototype in drivers/staging/rtl8712/xmit_osdep.h should be updated
as well. With that:

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
>  drivers/staging/rtl8712/xmit_linux.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/staging/rtl8712/xmit_linux.c b/drivers/staging/rtl8712/xmit_linux.c
> index 4a93839bf947..e84b9fa231cd 100644
> --- a/drivers/staging/rtl8712/xmit_linux.c
> +++ b/drivers/staging/rtl8712/xmit_linux.c
> @@ -140,7 +140,7 @@ void r8712_xmit_complete(struct _adapter *padapter, struct xmit_frame *pxframe)
>  	pxframe->pkt = NULL;
>  }
>  
> -int r8712_xmit_entry(_pkt *pkt, struct  net_device *netdev)
> +netdev_tx_t r8712_xmit_entry(_pkt *pkt, struct  net_device *netdev)
>  {
>  	struct xmit_frame *xmitframe = NULL;
>  	struct _adapter *adapter = netdev_priv(netdev);
> @@ -165,11 +165,11 @@ int r8712_xmit_entry(_pkt *pkt, struct  net_device *netdev)
>  	}
>  	xmitpriv->tx_pkts++;
>  	xmitpriv->tx_bytes += xmitframe->attrib.last_txcmdsz;
> -	return 0;
> +	return NETDEV_TX_OK;
>  _xmit_entry_drop:
>  	if (xmitframe)
>  		r8712_free_xmitframe(xmitpriv, xmitframe);
>  	xmitpriv->tx_drop++;
>  	dev_kfree_skb_any(pkt);
> -	return 0;
> +	return NETDEV_TX_OK;
>  }
> -- 
> 2.37.2.789.g6183377224-goog
>