netdev - [PATCH iproute2-next 2/3] libbpf: Remove use of bpf_program__set_priv and bpf_program_

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Date:   Sat, 23 Apr 2022 09:22:59 -0600
From:   David Ahern <dsahern@...nel.org>
To:     netdev@...r.kernel.org
Cc:     stephen@...workplumber.org, toke@...hat.com, haliu@...hat.com,
        David Ahern <dsahern@...nel.org>
Subject: [PATCH iproute2-next 2/3] libbpf: Remove use of bpf_program__set_priv and bpf_program__priv

bpf_program__set_priv and bpf_program__priv are deprecated as of
libbpf v0.7+. Rather than store the map as priv on the program,
change find_legacy_tail_calls to take an argument to return a reference
to the map.

find_legacy_tail_calls is invoked twice from load_bpf_object - the
first time to check for programs that should be loaded. In this case
a reference to the map is not needed, but it does validate the map
exists. The second is invoked from update_legacy_tail_call_maps where
the map pointer is needed.

Signed-off-by: David Ahern <dsahern@...nel.org>
---
 lib/bpf_libbpf.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/lib/bpf_libbpf.c b/lib/bpf_libbpf.c
index f723f6310c28..7dd1faf536f4 100644
--- a/lib/bpf_libbpf.c
+++ b/lib/bpf_libbpf.c
@@ -151,7 +151,8 @@ handle_legacy_map_in_map(struct bpf_object *obj, struct bpf_map *inner_map,
 	return ret;
 }
 
-static int find_legacy_tail_calls(struct bpf_program *prog, struct bpf_object *obj)
+static int find_legacy_tail_calls(struct bpf_program *prog, struct bpf_object *obj,
+				  struct bpf_map **pmap)
 {
 	unsigned int map_id, key_id;
 	const char *sec_name;
@@ -175,8 +176,8 @@ static int find_legacy_tail_calls(struct bpf_program *prog, struct bpf_object *o
 	if (!map)
 		return -1;
 
-	/* Save the map here for later updating */
-	bpf_program__set_priv(prog, map, NULL);
+	if (pmap)
+		*pmap = map;
 
 	return 0;
 }
@@ -190,8 +191,10 @@ static int update_legacy_tail_call_maps(struct bpf_object *obj)
 	struct bpf_map *map;
 
 	bpf_object__for_each_program(prog, obj) {
-		map = bpf_program__priv(prog);
-		if (!map)
+		/* load_bpf_object has already verified find_legacy_tail_calls
+		 * succeeds when it should
+		 */
+		if (find_legacy_tail_calls(prog, obj, &map) < 0)
 			continue;
 
 		prog_fd = bpf_program__fd(prog);
@@ -275,7 +278,8 @@ static int load_bpf_object(struct bpf_cfg_in *cfg)
 
 		/* Only load the programs that will either be subsequently
 		 * attached or inserted into a tail call map */
-		if (find_legacy_tail_calls(p, obj) < 0 && !prog_to_attach) {
+		if (find_legacy_tail_calls(p, obj, NULL) < 0 &&
+		    !prog_to_attach) {
 			ret = bpf_program__set_autoload(p, false);
 			if (ret)
 				return -EINVAL;
-- 
2.24.3 (Apple Git-128)