Subject: Re: linux-next: build warning after merge of the net-next tree

From: Stephen Rothwell <[email-masked]>
Date: Wed, 19 Dec 2018 16:37:13 +1100

Hi Gustavo,

On Tue, 18 Dec 2018 21:07:06 -0600 "Gustavo A. R. Silva" <[email-masked]> wrote:
>
> On 12/18/18 8:42 PM, Stephen Rothwell wrote:
> > Hi all,
> > 
> > On Thu, 29 Nov 2018 11:24:28 +1100 Stephen Rothwell <[email-masked]> wrote:  
> >>
> >> After merging the net-next tree, today's linux-next build
> >> (x86_64_allmodconfig) produced this warning:
> >>
> >> drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c: In function 'run_xdp':
> >> drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c:324:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
> >>     bpf_warn_invalid_xdp_action(xdp_act);
> >>     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >> drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c:325:2: note: here
> >>    case XDP_ABORTED:
> >>    ^~~~
> >> drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c:326:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
> >>     trace_xdp_exception(priv->net_dev, xdp_prog, xdp_act);
> >>     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >> drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c:327:2: note: here
> >>    case XDP_DROP:
> >>    ^~~~
> >>
> >> Introduced by commit
> >>
> >>    7e273a8ebdd3 ("dpaa2-eth: Add basic XDP support")
> >>
> >> This due to my use of -Wimplicit-fallthrough.  This is new code.  The
> >> warning can be suppressed by adding a comment like /* fall through */
> >> at the appropriate places to indicate that the fallthrough is intended.  
> > 
> > I am still seeing these warnings.
> >   
> 
> That's weird. I don't see them anymore in next-20181218.
> 
> They were fixed by this commit: c1cb11bcbd09f5f027cbc7fadddab169714948df

My mistake (patter mismatch :-)), there are very similar warnings in
drivers/net/veth.c which are older.  Someone could fix those if they
wanted to :-)

drivers/net/veth.c: In function 'veth_xdp_rcv_one':
drivers/net/veth.c:542:4: warning: this statement may fall through [-Wimplicit-fallthrough=]
    bpf_warn_invalid_xdp_action(act);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/net/veth.c:543:3: note: here
   case XDP_ABORTED:
   ^~~~
drivers/net/veth.c: In function 'veth_xdp_rcv_skb':
drivers/net/veth.c:663:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
   bpf_warn_invalid_xdp_action(act);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/net/veth.c:664:2: note: here
  case XDP_ABORTED:
  ^~~~

-- 
Cheers,
Stephen Rothwell