On Sun, Aug 4, 2019 at 8:59 PM Leon Romanovsky <leon@xxxxxxxxxx> wrote:
>
> On Sat, Aug 03, 2019 at 12:48:28AM +0800, Chuhong Yuan wrote:
> > refcount_t is better for reference counters since its
> > implementation can prevent overflows.
> > So convert atomic_t ref counters to refcount_t.
>
> I'm not thrilled to see those automatic conversion patches, especially
> for flows which can't overflow. There is nothing wrong in using atomic_t
> type of variable, do you have in mind flow which will cause to overflow?
>
> Thanks
I have to say that these patches are not done automatically...
Only the detection of problems is done by a script.
All conversions are done manually.
I am not sure whether the flow can cause an overflow.
But I think it is hard to ensure that a data path is impossible
to have problems in any cases including being attacked.
So I think it is better to do this minor revision to prevent
potential risk, just like we have done in mlx5/core/cq.c.
Regards,
Chuhong
> >
> > Signed-off-by: Chuhong Yuan <hslester96@xxxxxxxxx>
> > ---
> > Changes in v2:
> > - Add #include.
> >
> > drivers/net/ethernet/mellanox/mlx5/core/lib/vxlan.c | 9 +++++----
> > 1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/vxlan.c b/drivers/net/ethernet/mellanox/mlx5/core/lib/vxlan.c
> > index b9d4f4e19ff9..148b55c3db7a 100644
> > --- a/drivers/net/ethernet/mellanox/mlx5/core/lib/vxlan.c
> > +++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/vxlan.c
> > @@ -32,6 +32,7 @@
> >
> > #include <linux/kernel.h>
> > #include <linux/module.h>
> > +#include <linux/refcount.h>
> > #include <linux/mlx5/driver.h>
> > #include <net/vxlan.h>
> > #include "mlx5_core.h"
> > @@ -48,7 +49,7 @@ struct mlx5_vxlan {
> >
> > struct mlx5_vxlan_port {
> > struct hlist_node hlist;
> > - atomic_t refcount;
> > + refcount_t refcount;
> > u16 udp_port;
> > };
> >
> > @@ -113,7 +114,7 @@ int mlx5_vxlan_add_port(struct mlx5_vxlan *vxlan, u16 port)
> >
> > vxlanp = mlx5_vxlan_lookup_port(vxlan, port);
> > if (vxlanp) {
> > - atomic_inc(&vxlanp->refcount);
> > + refcount_inc(&vxlanp->refcount);
> > return 0;
> > }
> >
> > @@ -137,7 +138,7 @@ int mlx5_vxlan_add_port(struct mlx5_vxlan *vxlan, u16 port)
> > }
> >
> > vxlanp->udp_port = port;
> > - atomic_set(&vxlanp->refcount, 1);
> > + refcount_set(&vxlanp->refcount, 1);
> >
> > spin_lock_bh(&vxlan->lock);
> > hash_add(vxlan->htable, &vxlanp->hlist, port);
> > @@ -170,7 +171,7 @@ int mlx5_vxlan_del_port(struct mlx5_vxlan *vxlan, u16 port)
> > goto out_unlock;
> > }
> >
> > - if (atomic_dec_and_test(&vxlanp->refcount)) {
> > + if (refcount_dec_and_test(&vxlanp->refcount)) {
> > hash_del(&vxlanp->hlist);
> > remove = true;
> > }
> > --
> > 2.20.1
> >
