Re: [PATCH rdma-next v1 14/15] RDMA/core: Allow port_groups to be used with namespaces

[Leon Romanovsky <leon@kernel.org>]

On Mon, Jun 07, 2021 at 01:29:58PM +0000, Parav Pandit wrote:
> 
> 
> > From: Leon Romanovsky <leon@kernel.org>
> > Sent: Monday, June 7, 2021 1:48 PM
> > 
> > From: Jason Gunthorpe <jgg@nvidia.com>
> > 
> > Now that the port_groups data is being destroyed and managed by the core
> > code this restriction is no longer needed. All the ib_port_attrs are compatible
> > with the core's sysfs lifecycle.
> > 
> > Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> > Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> > ---
> >  drivers/infiniband/core/device.c | 10 ++++------
> > drivers/infiniband/core/sysfs.c  | 17 ++++++-----------
> >  2 files changed, 10 insertions(+), 17 deletions(-)

<...>

> > diff --git a/drivers/infiniband/core/sysfs.c b/drivers/infiniband/core/sysfs.c
> > index 09a2e1066df0..f42034fcf3d9 100644
> > --- a/drivers/infiniband/core/sysfs.c
> > +++ b/drivers/infiniband/core/sysfs.c
> > @@ -1236,11 +1236,9 @@ static struct ib_port *setup_port(struct
> > ib_core_device *coredev, int port_num,
> >  	ret = sysfs_create_groups(&p->kobj, p->groups_list);
> >  	if (ret)
> >  		goto err_del;
> > -	if (is_full_dev) {
> > -		ret = sysfs_create_groups(&p->kobj, device-
> > >ops.port_groups);
> > -		if (ret)
> > -			goto err_groups;
> > -	}
> > +	ret = sysfs_create_groups(&p->kobj, device->ops.port_groups);
> > +	if (ret)
> > +		goto err_groups;
> > 
> This will expose counters in all net namespaces in shared mode (default case).
> Application running in one net namespace will be able to monitor counters of other net namespace.
> This should be avoided.

In shared mode, we are sharing sysfs anyway and have two options to deal
with the port properties (counters):
1. Show them in all namespaces as being global to port which is shared anyway.
2. Show them in init_net namespace only and applications that were left
in this namespace will see not their counters anyway.

Why should we avoid "item 1"?

Thanks