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selftests/bpf: Wait for the netstamp_needed_key static key to be turned on

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After the previous patch that speeded up the test (by avoiding neigh
discovery in IPv6), the BPF CI occasionally hits this error:

rcv tstamp unexpected pkt rcv tstamp: actual 0 == expected 0

The test complains about the cmsg returned from the recvmsg() does not
have the rcv timestamp. Setting skb->tstamp or not is
controlled by a kernel static key "netstamp_needed_key". The static
key is enabled whenever this is at least one sk with the SOCK_TIMESTAMP
set.

The test_redirect_dtime does use setsockopt() to turn on
the SOCK_TIMESTAMP for the reading sk. In the kernel
net_enable_timestamp() has a delay to enable the "netstamp_needed_key"
when CONFIG_JUMP_LABEL is set. This potential delay is the likely reason
for packet missing rcv timestamp occasionally.

This patch is to create udp sockets with SOCK_TIMESTAMP set.
It sends and receives some packets until the received packet
has a rcv timestamp. It currently retries at most 5 times with 1s
in between. This should be enough to wait for the "netstamp_needed_key".
It then holds on to the socket and only closes it at the end of the test.
This guarantees that the test has the "netstamp_needed_key" key turned
on from the beginning.

To simplify the udp sockets setup, they are sending/receiving packets
in the same netns (ns_dst is used) and communicate over the "lo" dev.
Hence, the patch enables the "lo" dev in the ns_dst.

Fixes: c803475fd8 ("bpf: selftests: test skb->tstamp in redirect_neigh")
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240120060518.3604920-2-martin.lau@linux.dev
This commit is contained in:
Martin KaFai Lau 2024-01-19 22:05:18 -08:00 committed by Andrii Nakryiko
parent 177f1d083a
commit ce6f6cffae
1 changed files with 75 additions and 4 deletions
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79
tools/testing/selftests/bpf/prog_tests/tc_redirect.c
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@ -291,6 +291,7 @@ static int netns_setup_links_and_routes(struct netns_setup_result *result)
SYS(fail, "ip addr add " IP4_DST "/32 dev dst");
SYS(fail, "ip addr add " IP6_DST "/128 dev dst nodad");
SYS(fail, "ip link set dev dst up");
SYS(fail, "ip link set dev lo up");
SYS(fail, "ip route add " IP4_SRC "/32 dev dst scope global");
SYS(fail, "ip route add " IP4_NET "/16 dev dst scope global");
@ -468,7 +469,7 @@ static int set_forwarding(bool enable)
return 0;
}
static void rcv_tstamp(int fd, const char *expected, size_t s)
static int __rcv_tstamp(int fd, const char *expected, size_t s, __u64 *tstamp)
{
struct __kernel_timespec pkt_ts = {};
char ctl[CMSG_SPACE(sizeof(pkt_ts))];
@ -489,7 +490,7 @@ static void rcv_tstamp(int fd, const char *expected, size_t s)
ret = recvmsg(fd, &msg, 0);
if (!ASSERT_EQ(ret, s, "recvmsg"))
return;
return -1;
ASSERT_STRNEQ(data, expected, s, "expected rcv data");
cmsg = CMSG_FIRSTHDR(&msg);
@ -498,6 +499,12 @@ static void rcv_tstamp(int fd, const char *expected, size_t s)
memcpy(&pkt_ts, CMSG_DATA(cmsg), sizeof(pkt_ts));
pkt_ns = pkt_ts.tv_sec * NSEC_PER_SEC + pkt_ts.tv_nsec;
if (tstamp) {
/* caller will check the tstamp itself */
*tstamp = pkt_ns;
return 0;
}
ASSERT_NEQ(pkt_ns, 0, "pkt rcv tstamp");
ret = clock_gettime(CLOCK_REALTIME, &now_ts);
@ -507,6 +514,60 @@ static void rcv_tstamp(int fd, const char *expected, size_t s)
if (ASSERT_GE(now_ns, pkt_ns, "check rcv tstamp"))
ASSERT_LT(now_ns - pkt_ns, 5 * NSEC_PER_SEC,
"check rcv tstamp");
return 0;
}
static void rcv_tstamp(int fd, const char *expected, size_t s)
{
__rcv_tstamp(fd, expected, s, NULL);
}
static int wait_netstamp_needed_key(void)
{
int opt = 1, srv_fd = -1, cli_fd = -1, nretries = 0, err, n;
char buf[] = "testing testing";
struct nstoken *nstoken;
__u64 tstamp = 0;
nstoken = open_netns(NS_DST);
if (!nstoken)
return -1;
srv_fd = start_server(AF_INET6, SOCK_DGRAM, "::1", 0, 0);
if (!ASSERT_GE(srv_fd, 0, "start_server"))
goto done;
err = setsockopt(srv_fd, SOL_SOCKET, SO_TIMESTAMPNS_NEW,
&opt, sizeof(opt));
if (!ASSERT_OK(err, "setsockopt(SO_TIMESTAMPNS_NEW)"))
goto done;
cli_fd = connect_to_fd(srv_fd, TIMEOUT_MILLIS);
if (!ASSERT_GE(cli_fd, 0, "connect_to_fd"))
goto done;
again:
n = write(cli_fd, buf, sizeof(buf));
if (!ASSERT_EQ(n, sizeof(buf), "send to server"))
goto done;
err = __rcv_tstamp(srv_fd, buf, sizeof(buf), &tstamp);
if (!ASSERT_OK(err, "__rcv_tstamp"))
goto done;
if (!tstamp && nretries++ < 5) {
sleep(1);
printf("netstamp_needed_key retry#%d\n", nretries);
goto again;
}
done:
if (!tstamp && srv_fd != -1) {
close(srv_fd);
srv_fd = -1;
}
if (cli_fd != -1)
close(cli_fd);
close_netns(nstoken);
return srv_fd;
}
static void snd_tstamp(int fd, char *b, size_t s)
@ -843,11 +904,20 @@ static void test_tc_redirect_dtime(struct netns_setup_result *setup_result)
{
struct test_tc_dtime *skel;
struct nstoken *nstoken;
int err;
int hold_tstamp_fd, err;
/* Hold a sk with the SOCK_TIMESTAMP set to ensure there
* is no delay in the kernel net_enable_timestamp().
* This ensures the following tests must have
* non zero rcv tstamp in the recvmsg().
*/
hold_tstamp_fd = wait_netstamp_needed_key();
if (!ASSERT_GE(hold_tstamp_fd, 0, "wait_netstamp_needed_key"))
return;
skel = test_tc_dtime__open();
if (!ASSERT_OK_PTR(skel, "test_tc_dtime__open"))
return;
goto done;
skel->rodata->IFINDEX_SRC = setup_result->ifindex_src_fwd;
skel->rodata->IFINDEX_DST = setup_result->ifindex_dst_fwd;
@ -892,6 +962,7 @@ static void test_tc_redirect_dtime(struct netns_setup_result *setup_result)
done:
test_tc_dtime__destroy(skel);
close(hold_tstamp_fd);
}
static void test_tc_redirect_neigh_fib(struct netns_setup_result *setup_result)