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bpf: map_get_next_key to return first key on NULL

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When iterating through a map, we need to find a key that does not exist
in the map so map_get_next_key will give us the first key of the map.
This often requires a lot of guessing in production systems.

This patch makes map_get_next_key return the first key when the key
pointer in the parameter is NULL.

Signed-off-by: Teng Qin <qinteng@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Teng Qin
2017-04-24 19:00:37 -07:00
committed by David S. Miller
parent 472ecf084a
commit 8fe4592438
5 changed files with 49 additions and 19 deletions
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10
include/trace/events/bpf.h
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@@ -321,11 +321,14 @@ TRACE_EVENT(bpf_map_next_key,
__dynamic_array(u8, key, map->key_size)
__dynamic_array(u8, nxt, map->key_size)
__field(bool, key_trunc)
__field(bool, key_null)
__field(int, ufd)
),
TP_fast_assign(
memcpy(__get_dynamic_array(key), key, map->key_size);
if (key)
memcpy(__get_dynamic_array(key), key, map->key_size);
__entry->key_null = !key;
memcpy(__get_dynamic_array(nxt), key_next, map->key_size);
__entry->type = map->map_type;
__entry->key_len = min(map->key_size, 16U);
@@ -336,8 +339,9 @@ TRACE_EVENT(bpf_map_next_key,
TP_printk("map type=%s ufd=%d key=[%s%s] next=[%s%s]",
__print_symbolic(__entry->type, __MAP_TYPE_SYM_TAB),
__entry->ufd,
__print_hex(__get_dynamic_array(key), __entry->key_len),
__entry->key_trunc ? " ..." : "",
__entry->key_null ? "NULL" : __print_hex(__get_dynamic_array(key),
__entry->key_len),
__entry->key_trunc && !__entry->key_null ? " ..." : "",
__print_hex(__get_dynamic_array(nxt), __entry->key_len),
__entry->key_trunc ? " ..." : "")
);