Subject: Re: [PATCH] cxgb3: Convert from atomic_t to refcount_t on l2t_entry->refcnt

From: Leon Romanovsky <[email-masked]>
Date: Sun, 18 Jul 2021 13:42:53 +0300

On Sat, Jul 17, 2021 at 06:16:15PM +0800, Xiyu Yang wrote:
> refcount_t type and corresponding API can protect refcounters from
> accidental underflow and overflow and further use-after-free situations.
> 
> Signed-off-by: Xiyu Yang <[email-masked]>
> Signed-off-by: Xin Tan <[email-masked]>
> ---
>  drivers/net/ethernet/chelsio/cxgb3/l2t.c | 15 ++++++++-------
>  drivers/net/ethernet/chelsio/cxgb3/l2t.h | 10 +++++++---
>  2 files changed, 15 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/net/ethernet/chelsio/cxgb3/l2t.c b/drivers/net/ethernet/chelsio/cxgb3/l2t.c
> index 9749d1239f58..0f2a47bc20d8 100644
> --- a/drivers/net/ethernet/chelsio/cxgb3/l2t.c
> +++ b/drivers/net/ethernet/chelsio/cxgb3/l2t.c
> @@ -225,10 +225,11 @@ static struct l2t_entry *alloc_l2e(struct l2t_data *d)
>  
>  	/* there's definitely a free entry */
>  	for (e = d->rover, end = &d->l2tab[d->nentries]; e != end; ++e)
> -		if (atomic_read(&e->refcnt) == 0)
> +		if (refcount_read(&e->refcnt) == 0)

All those atomic_t to refcount_t patches can't be right, refcount_t can't be 0.

Thanks