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authorMartin KaFai Lau <kafai@fb.com>2020-03-04 17:34:47 -0800
committerAlexei Starovoitov <ast@kernel.org>2020-03-05 14:15:48 -0800
commit8e5290e710f4ffe8e9f8813e2ed0397a94d7b2f1 (patch)
tree62f38b9dceaca7363c23fa392c3dedf95b34939e /kernel/bpf
parenta35a76faad53429b52a8937b69fdeee5b4e5f935 (diff)
bpf: Return better error value in delete_elem for struct_ops map
The current always succeed behavior in bpf_struct_ops_map_delete_elem() is not ideal for userspace tool. It can be improved to return proper error value. If it is in TOBEFREE, it means unregistration has been already done before but it is in progress and waiting for the subsystem to clear the refcnt to zero, so -EINPROGRESS. If it is INIT, it means the struct_ops has not been registered yet, so -ENOENT. Fixes: 85d33df357b6 ("bpf: Introduce BPF_MAP_TYPE_STRUCT_OPS") Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200305013447.535326-1-kafai@fb.com
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/bpf_struct_ops.c14
1 files changed, 11 insertions, 3 deletions
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index 042f95534f86..68a89a9f7ccd 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -482,13 +482,21 @@ static int bpf_struct_ops_map_delete_elem(struct bpf_map *map, void *key)
prev_state = cmpxchg(&st_map->kvalue.state,
BPF_STRUCT_OPS_STATE_INUSE,
BPF_STRUCT_OPS_STATE_TOBEFREE);
- if (prev_state == BPF_STRUCT_OPS_STATE_INUSE) {
+ switch (prev_state) {
+ case BPF_STRUCT_OPS_STATE_INUSE:
st_map->st_ops->unreg(&st_map->kvalue.data);
if (refcount_dec_and_test(&st_map->kvalue.refcnt))
bpf_map_put(map);
+ return 0;
+ case BPF_STRUCT_OPS_STATE_TOBEFREE:
+ return -EINPROGRESS;
+ case BPF_STRUCT_OPS_STATE_INIT:
+ return -ENOENT;
+ default:
+ WARN_ON_ONCE(1);
+ /* Should never happen. Treat it as not found. */
+ return -ENOENT;
}
-
- return 0;
}
static void bpf_struct_ops_map_seq_show_elem(struct bpf_map *map, void *key,