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Date:   Tue, 13 Sep 2022 15:35:39 -0700
From:   Nathan Chancellor <nathan@kernel.org>
To:     Nathan Huckleberry <nhuck@google.com>
Cc:     Dan Carpenter <error27@gmail.com>, llvm@lists.linux.dev,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>, linux-staging@lists.linux.dev,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] staging: octeon: Fix return type of cvm_oct_xmit and
 cvm_oct_xmit_pow
Message-ID: <YyEFu8uzoxK64p0Y@dev-arch.thelio-3990X>
References: <20220912214523.929094-1-nhuck@google.com>
 <YyEFNA3nVShxwkJT@dev-arch.thelio-3990X>
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On Tue, Sep 13, 2022 at 03:33:24PM -0700, Nathan Chancellor wrote:
> On Mon, Sep 12, 2022 at 02:45:20PM -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>

Sorry, forgot to point out that the prototypes in
drivers/staging/octeon/ethernet-tx.h should be updated as well.

> > ---
> >  drivers/staging/octeon/ethernet-tx.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 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;
> > -- 
> > 2.37.2.789.g6183377224-goog
> > 
>