linux-kernel - Re: [Intel-wired-lan] [PATCH 2/2] ixgbe: Use refcount

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Date:   Mon, 5 Aug 2019 15:02:33 -0700
From:   Alexander Duyck <alexander.duyck@...il.com>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc:     Chuhong Yuan <hslester96@...il.com>,
        Network Development <netdev@...r.kernel.org>,
        intel-wired-lan <intel-wired-lan@...ts.osuosl.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "David S . Miller" <davem@...emloft.net>
Subject: Re: [Intel-wired-lan] [PATCH 2/2] ixgbe: Use refcount_t for refcount

On Fri, Aug 2, 2019 at 6:47 AM Willem de Bruijn
<willemdebruijn.kernel@...il.com> wrote:
>
> On Fri, Aug 2, 2019 at 6:55 AM Chuhong Yuan <hslester96@...il.com> wrote:
> >
> > refcount_t is better for reference counters since its
> > implementation can prevent overflows.
> > So convert atomic_t ref counters to refcount_t.
> >
> > Also convert refcount from 0-based to 1-based.
> >
> > This patch depends on PATCH 1/2.
> >
> > Signed-off-by: Chuhong Yuan <hslester96@...il.com>
> > ---
> >  drivers/net/ethernet/intel/ixgbe/ixgbe_fcoe.c | 6 +++---
> >  drivers/net/ethernet/intel/ixgbe/ixgbe_fcoe.h | 2 +-
> >  2 files changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_fcoe.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_fcoe.c
> > index 00710f43cfd2..d313d00065cd 100644
> > --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_fcoe.c
> > +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_fcoe.c
> > @@ -773,7 +773,7 @@ int ixgbe_setup_fcoe_ddp_resources(struct ixgbe_adapter *adapter)
> >
> >         fcoe->extra_ddp_buffer = buffer;
> >         fcoe->extra_ddp_buffer_dma = dma;
> > -       atomic_set(&fcoe->refcnt, 0);
> > +       refcount_set(&fcoe->refcnt, 1);
>
> Same point as in the cxgb4 driver patch: how can you just change the
> initial value without modifying the condition for release?
>
> This is not a suggestion to resubmit all these changes again with a
> change to the release condition.

So I am pretty sure this patch is badly broken. It doesn't make any
sense to be resetting with the refcnt in
ixgbe_setup_fcoe_ddp_resources. The value is initialized to zero when
the adapter structure was allocated.

Consider this a NAK from me.