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samples/bpf: Fix map iteration in xdp1_user

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BPF map iteration in xdp1_user results in endless loop without any
output, because the return value of bpf_map_get_next_key() is checked
against the wrong value.

Other call locations of bpf_map_get_next_key() check for equal 0 for
continuing the iteration. xdp1_user checks against unequal -1. This is
wrong for a function which can return arbitrary negative errno values,
because a return value of e.g. -2 results in an endless loop.

With this fix xdp1_user is printing statistics again:
proto 0:          1 pkt/s
proto 0:          1 pkt/s
proto 17:     107383 pkt/s
proto 17:     881655 pkt/s
proto 17:     882083 pkt/s
proto 17:     881758 pkt/s

Fixes: bd054102a8 ("libbpf: enforce strict libbpf 1.0 behaviors")
Signed-off-by: Gerhard Engleder <gerhard@engleder-embedded.com>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20221013200922.17167-1-gerhard@engleder-embedded.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
This commit is contained in:
Gerhard Engleder 2022-10-13 22:09:22 +02:00 committed by Martin KaFai Lau
parent a526a3cc9c
commit 05ee658c65
1 changed files with 1 additions and 1 deletions
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2
samples/bpf/xdp1_user.c
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@ -51,7 +51,7 @@ static void poll_stats(int map_fd, int interval)
sleep(interval);
while (bpf_map_get_next_key(map_fd, &key, &key) != -1) {
while (bpf_map_get_next_key(map_fd, &key, &key) == 0) {
__u64 sum = 0;
assert(bpf_map_lookup_elem(map_fd, &key, values) == 0);