When a BPF-map type doesn't support having a BTF info associated, the
bpf_map_ops->map_check_btf is set to map_check_no_btf(). This function
map_check_no_btf() currently returns -ENOTSUPP, which result in a very
confusing error message in libbpf, see below.
The errno ENOTSUPP is part of the kernels internal errno in file
include/linux/errno.h. As is stated in the file, these "should never be seen
by user programs."
Choosing errno EUCLEAN instead, which translated to "Structure needs
cleaning" by strerror(3). This hopefully leads people to think about data
structures which BTF is all about.
Before this change end-users of libbpf will see:
libbpf: Error in bpf_create_map_xattr(cpu_map):ERROR: strerror_r(-524)=22(-524). Retrying without BTF.
After this change end-users of libbpf will see:
libbpf: Error in bpf_create_map_xattr(cpu_map):Structure needs cleaning(-117). Retrying without BTF.
Fixes: e8d2bec04579 ("bpf: decouple btf from seq bpf fs dump and enable more maps")
Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
---
kernel/bpf/syscall.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index d13b804ff045..ecde7d938421 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -732,7 +732,7 @@ int map_check_no_btf(const struct bpf_map *map,
const struct btf_type *key_type,
const struct btf_type *value_type)
{
- return -ENOTSUPP;
+ return -EUCLEAN;
}
static int map_check_btf(struct bpf_map *map, const struct btf *btf,
