bpf: pass a struct with offload callbacks to bpf_offload_dev_create()

For passing device functions for offloaded eBPF programs, there used to
be no place where to store the pointer without making the non-offloaded
programs pay a memory price.

As a consequence, three functions were called with ndo_bpf() through
specific commands. Now that we have struct bpf_offload_dev, and since
none of those operations rely on RTNL, we can turn these three commands
into hooks inside the struct bpf_prog_offload_ops, and pass them as part
of bpf_offload_dev_create().

This commit effectively passes a pointer to the struct to
bpf_offload_dev_create(). We temporarily have two struct
bpf_prog_offload_ops instances, one under offdev->ops and one under
offload->dev_ops. The next patches will make the transition towards the
former, so that offload->dev_ops can be removed, and callbacks relying
on ndo_bpf() added to offdev->ops as well.

While at it, rename "nfp_bpf_analyzer_ops" as "nfp_bpf_dev_ops" (and
similarly for netdevsim).

Suggested-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

kernel/bpf/offload.c

@@ -33,6 +33,7 @@
 static DECLARE_RWSEM(bpf_devs_lock);
 
 struct bpf_offload_dev {
+	const struct bpf_prog_offload_ops *ops;
 	struct list_head netdevs;
 };
 
@@ -655,7 +656,8 @@ unlock:
 }
 EXPORT_SYMBOL_GPL(bpf_offload_dev_netdev_unregister);
 
-struct bpf_offload_dev *bpf_offload_dev_create(void)
+struct bpf_offload_dev *
+bpf_offload_dev_create(const struct bpf_prog_offload_ops *ops)
 {
 	struct bpf_offload_dev *offdev;
 	int err;
@@ -673,6 +675,7 @@ struct bpf_offload_dev *bpf_offload_dev_create(void)
 	if (!offdev)
 		return ERR_PTR(-ENOMEM);
 
+	offdev->ops = ops;
 	INIT_LIST_HEAD(&offdev->netdevs);
 
 	return offdev;