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Date:   Tue, 13 Sep 2022 16:22:23 -0700
From:   Nathan Chancellor <nathan@kernel.org>
To:     Nathan Huckleberry <nhuck@google.com>
Cc:     error27@gmail.com, gregkh@linuxfoundation.org,
        linux-kernel@vger.kernel.org, linux-staging@lists.linux.dev,
        llvm@lists.linux.dev, ndesaulniers@google.com, trix@redhat.com
Subject: Re: [PATCH v2] staging: octeon: Fix return type of cvm_oct_xmit and
 cvm_oct_xmit_pow
Message-ID: <YyEQr//Iq7bautrm@dev-arch.thelio-3990X>
References: <YyEFu8uzoxK64p0Y@dev-arch.thelio-3990X>
 <20220913230412.225957-1-nhuck@google.com>
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On Tue, Sep 13, 2022 at 04:04:12PM -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 cvm_oct_xmit and cvm_oct_xmit_pow 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>

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

> 
> Changes v1 -> v2:
>  - Update function signatures in ethernet-tx.h.
> 
> ---
>  drivers/staging/octeon/ethernet-tx.c | 4 ++--
>  drivers/staging/octeon/ethernet-tx.h | 4 ++--
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/staging/octeon/ethernet-tx.c b/drivers/staging/octeon/ethernet-tx.c
> index 1ad94c5060b5..a36e36701c74 100644
> --- a/drivers/staging/octeon/ethernet-tx.c
> +++ b/drivers/staging/octeon/ethernet-tx.c
> @@ -125,7 +125,7 @@ static void cvm_oct_free_tx_skbs(struct net_device *dev)
>   *
>   * Returns Always returns NETDEV_TX_OK
>   */
> -int cvm_oct_xmit(struct sk_buff *skb, struct net_device *dev)
> +netdev_tx_t cvm_oct_xmit(struct sk_buff *skb, struct net_device *dev)
>  {
>  	union cvmx_pko_command_word0 pko_command;
>  	union cvmx_buf_ptr hw_buffer;
> @@ -506,7 +506,7 @@ int cvm_oct_xmit(struct sk_buff *skb, struct net_device *dev)
>   * @dev:    Device info structure
>   * Returns Always returns zero
>   */
> -int cvm_oct_xmit_pow(struct sk_buff *skb, struct net_device *dev)
> +netdev_tx_t cvm_oct_xmit_pow(struct sk_buff *skb, struct net_device *dev)
>  {
>  	struct octeon_ethernet *priv = netdev_priv(dev);
>  	void *packet_buffer;
> diff --git a/drivers/staging/octeon/ethernet-tx.h b/drivers/staging/octeon/ethernet-tx.h
> index 78936e9b33b0..6c524668f65a 100644
> --- a/drivers/staging/octeon/ethernet-tx.h
> +++ b/drivers/staging/octeon/ethernet-tx.h
> @@ -5,8 +5,8 @@
>   * Copyright (c) 2003-2007 Cavium Networks
>   */
>  
> -int cvm_oct_xmit(struct sk_buff *skb, struct net_device *dev);
> -int cvm_oct_xmit_pow(struct sk_buff *skb, struct net_device *dev);
> +netdev_tx_t cvm_oct_xmit(struct sk_buff *skb, struct net_device *dev);
> +netdev_tx_t cvm_oct_xmit_pow(struct sk_buff *skb, struct net_device *dev);
>  int cvm_oct_transmit_qos(struct net_device *dev, void *work_queue_entry,
>  			 int do_free, int qos);
>  void cvm_oct_tx_initialize(void);
> -- 
> 2.37.2.789.g6183377224-goog
>