From: Martin KaFai Lau martin.lau@kernel.org
[ Upstream commit ce6f6cffaeaa0a3bcdafcae7fe03c68c3afae631 ]
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: c803475fd8dd ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- .../selftests/bpf/prog_tests/tc_redirect.c | 79 ++++++++++++++++++- 1 file changed, 75 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/tc_redirect.c b/tools/testing/selftests/bpf/prog_tests/tc_redirect.c index 610887157fd85..dbe06aeaa2b27 100644 --- a/tools/testing/selftests/bpf/prog_tests/tc_redirect.c +++ b/tools/testing/selftests/bpf/prog_tests/tc_redirect.c @@ -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)