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Message-ID: <20240120031642.67014-1-kuniyu@amazon.com>
Date: Fri, 19 Jan 2024 19:16:42 -0800
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
<pabeni@...hat.com>
CC: Kuniyuki Iwashima <kuniyu@...zon.com>, Kuniyuki Iwashima
<kuni1840@...il.com>, <netdev@...r.kernel.org>
Subject: [PATCH v1 net] selftest: Don't reuse port for SO_INCOMING_CPU test.
Jakub reported that ASSERT_EQ(cpu, i) in so_incoming_cpu.c seems to
fire somewhat randomly.
# # RUN so_incoming_cpu.before_reuseport.test3 ...
# # so_incoming_cpu.c:191:test3:Expected cpu (32) == i (0)
# # test3: Test terminated by assertion
# # FAIL so_incoming_cpu.before_reuseport.test3
# not ok 3 so_incoming_cpu.before_reuseport.test3
When the test failed, not-yet-accepted CLOSE_WAIT sockets received
SYN with a "challenging" SEQ number, which was sent from an unexpected
CPU that did not create the receiver.
The test basically does:
1. for each cpu:
1-1. create a server
1-2. set SO_INCOMING_CPU
2. for each cpu:
2-1. set cpu affinity
2-2. create some clients
2-3. let clients connect() to the server on the same cpu
2-4. close() clients
3. for each server:
3-1. accept() all child sockets
3-2. check if all children have the same SO_INCOMING_CPU with the server
The root cause was the close() in 2-4. and net.ipv4.tcp_tw_reuse.
In a loop of 2., close() changed the client state to FIN_WAIT_2, and
the peer transitioned to CLOSE_WAIT.
In another loop of 2., connect() happened to select the same port of
the FIN_WAIT_2 socket, and it was reused as the default value of
net.ipv4.tcp_tw_reuse is 2.
As a result, the new client sent SYN to the CLOSE_WAIT socket from
a different CPU, and the receiver's sk_incoming_cpu was overwritten
with unexpected CPU ID.
Also, the SYN had a different SEQ number, so the CLOSE_WAIT socket
responded with Challenge ACK. The new client properly returned RST
and effectively killed the CLOSE_WAIT socket.
This way, all clients were created successfully, but the error was
detected later by 3-2., ASSERT_EQ(cpu, i).
To avoid the failure, let's make sure that (i) the number of clients
is less than the number of available ports and (ii) such reuse never
happens.
Fixes: 6df96146b202 ("selftest: Add test for SO_INCOMING_CPU.")
Reported-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
tools/testing/selftests/net/so_incoming_cpu.c | 68 ++++++++++++++-----
1 file changed, 50 insertions(+), 18 deletions(-)
diff --git a/tools/testing/selftests/net/so_incoming_cpu.c b/tools/testing/selftests/net/so_incoming_cpu.c
index a14818164102..e9fa14e10732 100644
--- a/tools/testing/selftests/net/so_incoming_cpu.c
+++ b/tools/testing/selftests/net/so_incoming_cpu.c
@@ -3,19 +3,16 @@
#define _GNU_SOURCE
#include <sched.h>
+#include <fcntl.h>
+
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/sysinfo.h>
#include "../kselftest_harness.h"
-#define CLIENT_PER_SERVER 32 /* More sockets, more reliable */
-#define NR_SERVER self->nproc
-#define NR_CLIENT (CLIENT_PER_SERVER * NR_SERVER)
-
FIXTURE(so_incoming_cpu)
{
- int nproc;
int *servers;
union {
struct sockaddr addr;
@@ -56,12 +53,47 @@ FIXTURE_VARIANT_ADD(so_incoming_cpu, after_all_listen)
.when_to_set = AFTER_ALL_LISTEN,
};
+static void write_sysctl(struct __test_metadata *_metadata,
+ char *filename, char *string)
+{
+ int fd, len, ret;
+
+ fd = open(filename, O_WRONLY);
+ ASSERT_NE(fd, -1);
+
+ len = strlen(string);
+ ret = write(fd, string, len);
+ ASSERT_EQ(ret, len);
+}
+
+static void setup_netns(struct __test_metadata *_metadata)
+{
+ ASSERT_EQ(unshare(CLONE_NEWNET), 0);
+ ASSERT_EQ(system("ip link set lo up"), 0);
+
+ write_sysctl(_metadata, "/proc/sys/net/ipv4/ip_local_port_range", "10000 60001");
+ write_sysctl(_metadata, "/proc/sys/net/ipv4/tcp_tw_reuse", "0");
+}
+
+#define NR_PORT (60001 - 10000 - 1)
+#define NR_CLIENT_PER_SERVER_DEFAULT 32
+static int nr_client_per_server, nr_server, nr_client;
+
FIXTURE_SETUP(so_incoming_cpu)
{
- self->nproc = get_nprocs();
- ASSERT_LE(2, self->nproc);
+ setup_netns(_metadata);
+
+ nr_server = get_nprocs();
+ ASSERT_LE(2, nr_server);
+
+ if (NR_CLIENT_PER_SERVER_DEFAULT * nr_server < NR_PORT)
+ nr_client_per_server = NR_CLIENT_PER_SERVER_DEFAULT;
+ else
+ nr_client_per_server = NR_PORT / nr_server;
+
+ nr_client = nr_client_per_server * nr_server;
- self->servers = malloc(sizeof(int) * NR_SERVER);
+ self->servers = malloc(sizeof(int) * nr_server);
ASSERT_NE(self->servers, NULL);
self->in_addr.sin_family = AF_INET;
@@ -74,7 +106,7 @@ FIXTURE_TEARDOWN(so_incoming_cpu)
{
int i;
- for (i = 0; i < NR_SERVER; i++)
+ for (i = 0; i < nr_server; i++)
close(self->servers[i]);
free(self->servers);
@@ -110,10 +142,10 @@ int create_server(struct __test_metadata *_metadata,
if (variant->when_to_set == BEFORE_LISTEN)
set_so_incoming_cpu(_metadata, fd, cpu);
- /* We don't use CLIENT_PER_SERVER here not to block
+ /* We don't use nr_client_per_server here not to block
* this test at connect() if SO_INCOMING_CPU is broken.
*/
- ret = listen(fd, NR_CLIENT);
+ ret = listen(fd, nr_client);
ASSERT_EQ(ret, 0);
if (variant->when_to_set == AFTER_LISTEN)
@@ -128,7 +160,7 @@ void create_servers(struct __test_metadata *_metadata,
{
int i, ret;
- for (i = 0; i < NR_SERVER; i++) {
+ for (i = 0; i < nr_server; i++) {
self->servers[i] = create_server(_metadata, self, variant, i);
if (i == 0) {
@@ -138,7 +170,7 @@ void create_servers(struct __test_metadata *_metadata,
}
if (variant->when_to_set == AFTER_ALL_LISTEN) {
- for (i = 0; i < NR_SERVER; i++)
+ for (i = 0; i < nr_server; i++)
set_so_incoming_cpu(_metadata, self->servers[i], i);
}
}
@@ -149,7 +181,7 @@ void create_clients(struct __test_metadata *_metadata,
cpu_set_t cpu_set;
int i, j, fd, ret;
- for (i = 0; i < NR_SERVER; i++) {
+ for (i = 0; i < nr_server; i++) {
CPU_ZERO(&cpu_set);
CPU_SET(i, &cpu_set);
@@ -162,7 +194,7 @@ void create_clients(struct __test_metadata *_metadata,
ret = sched_setaffinity(0, sizeof(cpu_set), &cpu_set);
ASSERT_EQ(ret, 0);
- for (j = 0; j < CLIENT_PER_SERVER; j++) {
+ for (j = 0; j < nr_client_per_server; j++) {
fd = socket(AF_INET, SOCK_STREAM, 0);
ASSERT_NE(fd, -1);
@@ -180,8 +212,8 @@ void verify_incoming_cpu(struct __test_metadata *_metadata,
int i, j, fd, cpu, ret, total = 0;
socklen_t len = sizeof(int);
- for (i = 0; i < NR_SERVER; i++) {
- for (j = 0; j < CLIENT_PER_SERVER; j++) {
+ for (i = 0; i < nr_server; i++) {
+ for (j = 0; j < nr_client_per_server; j++) {
/* If we see -EAGAIN here, SO_INCOMING_CPU is broken */
fd = accept(self->servers[i], &self->addr, &self->addrlen);
ASSERT_NE(fd, -1);
@@ -195,7 +227,7 @@ void verify_incoming_cpu(struct __test_metadata *_metadata,
}
}
- ASSERT_EQ(total, NR_CLIENT);
+ ASSERT_EQ(total, nr_client);
TH_LOG("SO_INCOMING_CPU is very likely to be "
"working correctly with %d sockets.", total);
}
--
2.30.2
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