bpf: offload: aggregate offloads per-device

Currently we have two lists of offloaded objects - programs and maps.
Netdevice unregister notifier scans those lists to orphan objects
associated with device being unregistered.  This puts unnecessary
(even if negligible) burden on all netdev unregister calls in BPF-
-enabled kernel.  The lists of objects may potentially get long
making the linear scan even more problematic.  There haven't been
complaints about this mechanisms so far, but it is suboptimal.

Instead of relying on notifiers, make the few BPF-capable drivers
register explicitly for BPF offloads.  The programs and maps will
now be collected per-device not on a global list, and only scanned
for removal when driver unregisters from BPF offloads.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/net/netdevsim/bpf.c b/drivers/net/netdevsim/bpf.c
index 357f9e62f306..c4a2829e0e1f 100644
--- a/drivers/net/netdevsim/bpf.c
+++ b/drivers/net/netdevsim/bpf.c
@@ -582,6 +582,8 @@ int nsim_bpf(struct net_device *dev, struct netdev_bpf *bpf)
 
 int nsim_bpf_init(struct netdevsim *ns)
 {
+	int err;
+
 	if (ns->sdev->refcnt == 1) {
 		INIT_LIST_HEAD(&ns->sdev->bpf_bound_progs);
 		INIT_LIST_HEAD(&ns->sdev->bpf_bound_maps);
@@ -592,6 +594,10 @@ int nsim_bpf_init(struct netdevsim *ns)
 			return -ENOMEM;
 	}
 
+	err = bpf_offload_dev_netdev_register(ns->netdev);
+	if (err)
+		return err;
+
 	debugfs_create_u32("bpf_offloaded_id", 0400, ns->ddir,
 			   &ns->bpf_offloaded_id);
 
@@ -625,6 +631,7 @@ void nsim_bpf_uninit(struct netdevsim *ns)
 	WARN_ON(ns->xdp.prog);
 	WARN_ON(ns->xdp_hw.prog);
 	WARN_ON(ns->bpf_offloaded);
+	bpf_offload_dev_netdev_unregister(ns->netdev);
 
 	if (ns->sdev->refcnt == 1) {
 		WARN_ON(!list_empty(&ns->sdev->bpf_bound_progs));