[PATCH] selftests: net: reuseport_bpf_numa: skip nodes not available

In some platforms the numa node numbers are not necessarily consecutive,
meaning that not all nodes from 0 to the value returned by
numa_max_node() are available on the system. Using node numbers which
are not available results on errors from libnuma such as:

---- IPv4 UDP ----
send node 0, receive socket 0
libnuma: Warning: Cannot read node cpumask from sysfs
./reuseport_bpf_numa: failed to pin to node: No such file or directory

Fix it by checking if the node number bit is set on numa_nodes_ptr,
which is defined on libnuma as "Set with all nodes the kernel has
exposed to userspace".

Signed-off-by: Kleber Sacilotto de Souza <redacted>
---
 tools/testing/selftests/net/reuseport_bpf_numa.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/net/reuseport_bpf_numa.c b/tools/testing/selftests/net/reuseport_bpf_numa.c
index c9f478b40996..b2eebf669b8c 100644
--- a/tools/testing/selftests/net/reuseport_bpf_numa.c
+++ b/tools/testing/selftests/net/reuseport_bpf_numa.c

@@ -211,12 +211,16 @@ static void test(int *rcv_fd, int len, int family, int proto)
 
 	/* Forward iterate */
 	for (node = 0; node < len; ++node) {
+		if (!numa_bitmask_isbitset(numa_nodes_ptr, node))
+			continue;
 		send_from_node(node, family, proto);
 		receive_on_node(rcv_fd, len, epfd, node, proto);
 	}
 
 	/* Reverse iterate */
 	for (node = len - 1; node >= 0; --node) {
+		if (!numa_bitmask_isbitset(numa_nodes_ptr, node))
+			continue;
 		send_from_node(node, family, proto);
 		receive_on_node(rcv_fd, len, epfd, node, proto);
 	}

-- 
2.30.2

Hello:

This patch was applied to bpf/bpf.git (master)
by Daniel Borkmann [off-list ref]:

On Mon,  1 Nov 2021 15:53:17 +0100 you wrote:

In some platforms the numa node numbers are not necessarily consecutive,
meaning that not all nodes from 0 to the value returned by
numa_max_node() are available on the system. Using node numbers which
are not available results on errors from libnuma such as:

---- IPv4 UDP ----
send node 0, receive socket 0
libnuma: Warning: Cannot read node cpumask from sysfs
./reuseport_bpf_numa: failed to pin to node: No such file or directory

[...]

Here is the summary with links:
  - selftests: net: reuseport_bpf_numa: skip nodes not available
    https://git.kernel.org/bpf/bpf/c/a38bc45a08e9

You are awesome, thank you!
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