[PATCH bpf-next v3 05/15] bpf: Replace prog_list_prog() check with direct pl->prog and pl->link check

[Amery Hung <ameryhung@gmail.com>]

From: Martin KaFai Lau <martin.lau@kernel.org>

prog_list_length() and compute_effective_progs() use !prog_list_prog(pl)
to skip a 'detaching' pl.

When pl->link is not NULL, prog_list_prog(pl) returns
the pl->link->link.prog. This does not work for the upcoming struct_ops
patch where pl->link is not NULL but pl->link->link.prog is NULL,
because a struct_ops map is attached to the cgroup instead of a BPF prog.

To prepare for the upcoming struct_ops patch, this patch
replaces the prog_list_prog() test with the
"!pl->prog && !pl->link". In __cgroup_bpf_detach(),
both pl->prog and pl->link are set to NULL, so testing
"!pl->prog && !pl->link" is the same test to tell
if a pl is being detached. This change should be a no-op.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Amery Hung <ameryhung@gmail.com>
---
 kernel/bpf/cgroup.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index b64f6757096c..b100c04cb9c8 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -408,7 +408,7 @@ static u32 prog_list_length(struct hlist_head *head, int *preorder_cnt)
 	u32 cnt = 0;
 
 	hlist_for_each_entry(pl, head, node) {
-		if (!prog_list_prog(pl))
+		if (!pl->prog && !pl->link)
 			continue;
 		if (preorder_cnt && (pl->flags & BPF_F_PREORDER))
 			(*preorder_cnt)++;
@@ -482,7 +482,7 @@ static int compute_effective_progs(struct cgroup *cgrp,
 
 		init_bstart = bstart;
 		hlist_for_each_entry(pl, &p->bpf.progs[atype], node) {
-			if (!prog_list_prog(pl))
+			if (!pl->prog && !pl->link)
 				continue;
 
 			if (pl->flags & BPF_F_PREORDER) {
-- 
2.52.0