Merge branch 'net-sched-propagate-extack-to-cls-offloads-on-destroy-and-only-with-skip_sw'

Jakub Kicinski says:

====================
net: sched: propagate extack to cls offloads on destroy and only with skip_sw

This series some of Jiri's comments and the fact that today drivers
may produce extack even if there is no skip_sw flag (meaning the
driver failure is not really a problem), and warning messages will
only confuse the users.

First patch propagates extack to destroy as requested by Jiri, extack
is then propagated to the driver callback for each classifier.  I chose
not to provide the extack on error paths.  As a rule of thumb it seems
best to keep the extack of the condition which caused the error.  E.g.

     err = this_will_fail(arg, extack);
     if (err) {
        undo_things(arg, NULL /* don't pass extack */);
	return err;
     }

Note that NL_SET_ERR_MSG() will ignore the message if extack is NULL.
I was pondering whether we should make NL_SET_ERR_MSG() refuse to
overwrite the msg, but there seem to be cases in the tree where extack
is set like this:

     err = this_will_fail(arg, extack);
     if (err) {
        undo_things(arg, NULL /* don't pass extack */);
	NL_SET_ERR_MSG(extack, "extack is set after undo call :/");
	return err;
     }

I think not passing extack to undo calls is reasonable.

v2:
 - rename the temporary tc_cls_common_offload_init().
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 11 deletions

diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
index c11e0fe23a17..8e5326bc6440 100644
--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -159,14 +159,14 @@ static int cls_bpf_offload_cmd(struct tcf_proto *tp, struct cls_bpf_prog *prog,
 	skip_sw = prog && tc_skip_sw(prog->gen_flags);
 	obj = prog ?: oldprog;
 
-	tc_cls_common_offload_init(&cls_bpf.common, tp, extack);
+	tc_cls_common_offload_init(&cls_bpf.common, tp, obj->gen_flags,
+				   extack);
 	cls_bpf.command = TC_CLSBPF_OFFLOAD;
 	cls_bpf.exts = &obj->exts;
 	cls_bpf.prog = prog ? prog->filter : NULL;
 	cls_bpf.oldprog = oldprog ? oldprog->filter : NULL;
 	cls_bpf.name = obj->bpf_name;
 	cls_bpf.exts_integrated = obj->exts_integrated;
-	cls_bpf.gen_flags = obj->gen_flags;
 
 	if (oldprog)
 		tcf_block_offload_dec(block, &oldprog->gen_flags);
@@ -212,11 +212,12 @@ static int cls_bpf_offload(struct tcf_proto *tp, struct cls_bpf_prog *prog,
 }
 
 static void cls_bpf_stop_offload(struct tcf_proto *tp,
-				 struct cls_bpf_prog *prog)
+				 struct cls_bpf_prog *prog,
+				 struct netlink_ext_ack *extack)
 {
 	int err;
 
-	err = cls_bpf_offload_cmd(tp, NULL, prog, NULL);
+	err = cls_bpf_offload_cmd(tp, NULL, prog, extack);
 	if (err)
 		pr_err("Stopping hardware offload failed: %d\n", err);
 }
@@ -227,13 +228,12 @@ static void cls_bpf_offload_update_stats(struct tcf_proto *tp,
 	struct tcf_block *block = tp->chain->block;
 	struct tc_cls_bpf_offload cls_bpf = {};
 
-	tc_cls_common_offload_init(&cls_bpf.common, tp, NULL);
+	tc_cls_common_offload_init(&cls_bpf.common, tp, prog->gen_flags, NULL);
 	cls_bpf.command = TC_CLSBPF_STATS;
 	cls_bpf.exts = &prog->exts;
 	cls_bpf.prog = prog->filter;
 	cls_bpf.name = prog->bpf_name;
 	cls_bpf.exts_integrated = prog->exts_integrated;
-	cls_bpf.gen_flags = prog->gen_flags;
 
 	tc_setup_cb_call(block, NULL, TC_SETUP_CLSBPF, &cls_bpf, false);
 }
@@ -290,12 +290,13 @@ static void cls_bpf_delete_prog_rcu(struct rcu_head *rcu)
 	tcf_queue_work(&prog->work);
 }
 
-static void __cls_bpf_delete(struct tcf_proto *tp, struct cls_bpf_prog *prog)
+static void __cls_bpf_delete(struct tcf_proto *tp, struct cls_bpf_prog *prog,
+			     struct netlink_ext_ack *extack)
 {
 	struct cls_bpf_head *head = rtnl_dereference(tp->root);
 
 	idr_remove_ext(&head->handle_idr, prog->handle);
-	cls_bpf_stop_offload(tp, prog);
+	cls_bpf_stop_offload(tp, prog, extack);
 	list_del_rcu(&prog->link);
 	tcf_unbind_filter(tp, &prog->res);
 	if (tcf_exts_get_net(&prog->exts))
@@ -309,18 +310,19 @@ static int cls_bpf_delete(struct tcf_proto *tp, void *arg, bool *last,
 {
 	struct cls_bpf_head *head = rtnl_dereference(tp->root);
 
-	__cls_bpf_delete(tp, arg);
+	__cls_bpf_delete(tp, arg, extack);
 	*last = list_empty(&head->plist);
 	return 0;
 }
 
-static void cls_bpf_destroy(struct tcf_proto *tp)
+static void cls_bpf_destroy(struct tcf_proto *tp,
+			    struct netlink_ext_ack *extack)
 {
 	struct cls_bpf_head *head = rtnl_dereference(tp->root);
 	struct cls_bpf_prog *prog, *tmp;
 
 	list_for_each_entry_safe(prog, tmp, &head->plist, link)
-		__cls_bpf_delete(tp, prog);
+		__cls_bpf_delete(tp, prog, extack);
 
 	idr_destroy(&head->handle_idr);
 	kfree_rcu(head, rcu);