bpf: offload: allow netdev to disappear while verifier is running

To allow verifier instruction callbacks without any extra locking
NETDEV_UNREGISTER notification would wait on a waitqueue for verifier
to finish.  This design decision was made when rtnl lock was providing
all the locking.  Use the read/write lock instead and remove the
workqueue.

Verifier will now call into the offload code, so dev_ops are moved
to offload structure.  Since verifier calls are all under
bpf_prog_is_dev_bound() we no longer need static inline implementations
to please builds with CONFIG_NET=n.

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

1 files changed, 7 insertions, 2 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 838eee1..669549f 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -17,6 +17,7 @@
 #include <linux/numa.h>
 #include <linux/wait.h>
 
+struct bpf_verifier_env;
 struct perf_event;
 struct bpf_prog;
 struct bpf_map;
@@ -184,14 +185,18 @@ struct bpf_verifier_ops {
 				  struct bpf_prog *prog, u32 *target_size);
 };
 
+struct bpf_prog_offload_ops {
+	int (*insn_hook)(struct bpf_verifier_env *env,
+			 int insn_idx, int prev_insn_idx);
+};
+
 struct bpf_dev_offload {
 	struct bpf_prog		*prog;
 	struct net_device	*netdev;
 	void			*dev_priv;
 	struct list_head	offloads;
 	bool			dev_state;
-	bool			verifier_running;
-	wait_queue_head_t	verifier_done;
+	const struct bpf_prog_offload_ops *dev_ops;
 };
 
 struct bpf_prog_aux {