Re: [PATCH] net: adaptec: remove dead code in set_vlan_mode

[Ion Badulescu]

On 11/20/20 6:17 PM, Jakub Kicinski wrote:
> On Fri, 20 Nov 2020 15:50:00 +0800 xiakaixu1987@xxxxxxxxx wrote:
> > From: Kaixu Xia <kaixuxia@xxxxxxxxxxx>
> >
> > The body of the if statement can be executed only when the variable
> > vlan_count equals to 32, so the condition of the while statement can
> > not be true and the while statement is dead code. Remove it.
> >
> > Reported-by: Tosk Robot <tencent_os_robot@xxxxxxxxxxx>
> > Signed-off-by: Kaixu Xia <kaixuxia@xxxxxxxxxxx>
> > ---
> >   drivers/net/ethernet/adaptec/starfire.c | 9 ++-------
> >   1 file changed, 2 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/adaptec/starfire.c b/drivers/net/ethernet/adaptec/starfire.c
> > index 555299737b51..ad27a9fa5e95 100644
> > --- a/drivers/net/ethernet/adaptec/starfire.c
> > +++ b/drivers/net/ethernet/adaptec/starfire.c
> > @@ -1754,14 +1754,9 @@ static u32 set_vlan_mode(struct netdev_private *np)
> >   		filter_addr += 16;
> >   		vlan_count++;
> >   	}
> > -	if (vlan_count == 32) {
> > +	if (vlan_count == 32)
> >   		ret |= PerfectFilterVlan;
> > -		while (vlan_count < 32) {
> > -			writew(0, filter_addr);
> > -			filter_addr += 16;
> > -			vlan_count++;
> > -		}
> > -	}
> > +
> >   	return ret;
> >   }
> >   #endif /* VLAN_SUPPORT */
>
> This got broken back in 2011:
>
> commit 5da96be53a16a62488316810d0c7c5d58ce3ee4f
> Author: Jiri Pirko <jpirko@xxxxxxxxxx>
> Date:   Wed Jul 20 04:54:31 2011 +0000
>
>      starfire: do vlan cleanup
>      
>      - unify vlan and nonvlan rx path
>      - kill np->vlgrp and netdev_vlan_rx_register
>      
>      Signed-off-by: Jiri Pirko <jpirko@xxxxxxxxxx>
>      Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
>
> The comparison to 32 was on a different variable before that change.
>
> Ion, do you think anyone is still using this driver?
>
> Maybe it's time we put it in the history book (by which I mean remove
> from the kernel).

Frankly, no, I don't know of any users, and that unfortunately includes 
myself. I still have two cards in my stash, but they're 64-bit PCI-X, so 
plugging them in would likely require taking a dremel to a 32-bit PCI 
slot to make it open-ended. (They do work in a 32-bit slot.)

Anyway, that filter code could use some fixing in other regards. So 
either we fix it properly (which I can submit a patch for), or clean it 
out for good.

-Ion