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| author | Yureka Lilian <yuka@yuka.dev> | 2025-08-14 20:01:12 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-10-19 16:21:29 +0200 |
| commit | 3a502b0eefcfcec790f04be1735c77ccfded114c (patch) | |
| tree | 0df5fdfc246539159194c68ac4bd926e16c1d9e5 /tools | |
| parent | c6552fac719902530ed62d50f0213ef9fe8a8d6b (diff) | |
| download | linux-3a502b0eefcfcec790f04be1735c77ccfded114c.tar.gz linux-3a502b0eefcfcec790f04be1735c77ccfded114c.tar.bz2 linux-3a502b0eefcfcec790f04be1735c77ccfded114c.zip | |
libbpf: Fix reuse of DEVMAP
[ Upstream commit 6c6b4146deb12d20f42490d5013f2043df942161 ]
Previously, re-using pinned DEVMAP maps would always fail, because
get_map_info on a DEVMAP always returns flags with BPF_F_RDONLY_PROG set,
but BPF_F_RDONLY_PROG being set on a map during creation is invalid.
Thus, ignore the BPF_F_RDONLY_PROG flag in the flags returned from
get_map_info when checking for compatibility with an existing DEVMAP.
The same problem is handled in a third-party ebpf library:
- https://github.com/cilium/ebpf/issues/925
- https://github.com/cilium/ebpf/pull/930
Fixes: 0cdbb4b09a06 ("devmap: Allow map lookups from eBPF")
Signed-off-by: Yureka Lilian <yuka@yuka.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250814180113.1245565-3-yuka@yuka.dev
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/lib/bpf/libbpf.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 13dea519e59f..d9589c92e05d 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -4485,6 +4485,16 @@ static bool map_is_reuse_compat(const struct bpf_map *map, int map_fd) return false; } + /* + * bpf_get_map_info_by_fd() for DEVMAP will always return flags with + * BPF_F_RDONLY_PROG set, but it generally is not set at map creation time. + * Thus, ignore the BPF_F_RDONLY_PROG flag in the flags returned from + * bpf_get_map_info_by_fd() when checking for compatibility with an + * existing DEVMAP. + */ + if (map->def.type == BPF_MAP_TYPE_DEVMAP || map->def.type == BPF_MAP_TYPE_DEVMAP_HASH) + map_info.map_flags &= ~BPF_F_RDONLY_PROG; + return (map_info.type == map->def.type && map_info.key_size == map->def.key_size && map_info.value_size == map->def.value_size && |