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bpf: error handling when map_lookup_elem isn't supported 

The error value returned by map_lookup_elem doesn't differentiate
whether lookup was failed because of invalid key or lookup is not
supported.

Lets add handling for -EOPNOTSUPP return value of map_lookup_elem()
method of map, with expectation from map's implementation that it
should return -EOPNOTSUPP if lookup is not supported.

The errno for bpf syscall for BPF_MAP_LOOKUP_ELEM command will be set
to EOPNOTSUPP if map lookup is not supported.

Signed-off-by: Prashant Bhole <bhole_prashant_q7@lab.ntt.co.jp>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Prashant Bhole 2018-10-09 10:04:49 +09:00 committed by Alexei Starovoitov
parent 8af03d1ae2
commit 509db2833e
1 changed files with 7 additions and 2 deletions
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9
kernel/bpf/syscall.c
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@ -719,10 +719,15 @@ static int map_lookup_elem(union bpf_attr *attr)
} else {
rcu_read_lock();
ptr = map->ops->map_lookup_elem(map, key);
if (ptr)
if (IS_ERR(ptr)) {
err = PTR_ERR(ptr);
} else if (!ptr) {
err = -ENOENT;
} else {
err = 0;
memcpy(value, ptr, value_size);
}
rcu_read_unlock();
err = ptr ? 0 : -ENOENT;
}
if (err)