On Wed, Sep 16, 2020 at 03:44:29PM +0300, Leon Romanovsky wrote:
> On Wed, Sep 16, 2020 at 09:04:40AM -0300, Jason Gunthorpe wrote:
> > On Wed, Sep 16, 2020 at 01:37:10PM +0300, Leon Romanovsky wrote:
> > > It depends on how you want to treat errors from rdma_read_gid_attr_ndev_rcu().
> > > Current check allows us to ensure that any error returned by this call is
> > > handled.
> > >
> > > Otherwise we will find ourselves with something like this:
> > > ndev = rdma_read_gid_attr_ndev_rcu(gid_attr);
> > > if (IS_ERR(ndev)) {
> > > if (rdma_protocol_roce())
> > > goto error;
> > > if (ERR_PTR(ndev) != -ENODEV)
> > > goto error;
> > > }
> >
> > Isn't it just
> >
> > if (IS_ERR(ndev)) {
> > if (ERR_PTR(ndev) != -ENODEV)
> > goto error;
> > index = -1;
> > }
> >
> > Which seems fine and clear enough
>
> It is a problem if roce device returned -ENODEV.
Can it happen? RCU I suppose, but I think this is an issue in
rdma_read_gid_attr_ndev_rcu() - it should not return ENODEV if the RCU
shows the gid_attr is being concurrently destroyed
Jason
