samples/bpf: Fix map iteration in xdp1_user
authorGerhard Engleder <gerhard@engleder-embedded.com>
Thu, 13 Oct 2022 20:09:22 +0000 (22:09 +0200)
committerMartin KaFai Lau <martin.lau@kernel.org>
Wed, 19 Oct 2022 17:56:21 +0000 (10:56 -0700)
commit05ee658c654bacda03f7fecef367e62aaf8e1cfe
tree9809d8442a0399b1b1ddd60b22d90c15619121c3
parenta526a3cc9c8d426713f8bebc18ebbe39a8495d82
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