When a BPF map of type BPF_MAP_TYPE_PERF_EVENT_ARRAY doesn't have the
max_entries parameter set, this parameter will be set to the number of
possible CPUs. Due to this, the map_is_reuse_compat function will return
false, causing the following error when trying to reuse the map:
libbpf: couldn't reuse pinned map at '/sys/fs/bpf/m_logging': parameter mismatch
Fix this by checking against the number of possible CPUs if the
max_entries parameter is not set in the map definition.
Fixes: 57a00f41644f ("libbpf: Add auto-pinning of maps when loading BPF objects")
Signed-off-by: Stijn Tintel <stijn@xxxxxxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 7f10dd501a52..b076ab728f0e 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4750,7 +4750,7 @@ static bool map_is_reuse_compat(const struct bpf_map *map, int map_fd)
struct bpf_map_info map_info = {};
char msg[STRERR_BUFSIZE];
__u32 map_info_len;
- int err;
+ int def_max_entries, err;
map_info_len = sizeof(map_info);
@@ -4763,10 +4763,15 @@ static bool map_is_reuse_compat(const struct bpf_map *map, int map_fd)
return false;
}
+ if (map->def.type == BPF_MAP_TYPE_PERF_EVENT_ARRAY && !map->def.max_entries)
+ def_max_entries = libbpf_num_possible_cpus();
+ else
+ def_max_entries = map->def.max_entries;
+
return (map_info.type == map->def.type &&
map_info.key_size == map->def.key_size &&
map_info.value_size == map->def.value_size &&
- map_info.max_entries == map->def.max_entries &&
+ map_info.max_entries == def_max_entries &&
map_info.map_flags == map->def.map_flags &&
map_info.map_extra == map->map_extra);
}
--
2.34.1
