From 05ee658c654bacda03f7fecef367e62aaf8e1cfe Mon Sep 17 00:00:00 2001
From: Gerhard Engleder <gerhard@engleder-embedded.com>
Date: Thu, 13 Oct 2022 22:09:22 +0200
Subject: [PATCH] samples/bpf: Fix map iteration in xdp1_user
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: bd054102a8c7 ("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>
---
samples/bpf/xdp1_user.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/samples/bpf/xdp1_user.c b/samples/bpf/xdp1_user.c
index ac370e638fa3d..281dc964de8da 100644
--- a/samples/bpf/xdp1_user.c
+++ b/samples/bpf/xdp1_user.c
@@ -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);
--
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