[PATCH AUTOSEL 6.8 29/30] selftests: net: fix timestamp not arriving in cmsg_time.sh

Sasha Levin
2024-05-27T14:15:30Z

From: Jakub Kicinski <kuba@kernel.org>

[ Upstream commit 2d3b8dfd82d76b1295167c6453d683ab99e50794 ]

On slow machines the SND timestamp sometimes doesn't arrive before
we quit. The test only waits as long as the packet delay, so it's
easy for a race condition to happen.

Double the wait but do a bit of polling, once the SND timestamp
arrives there's no point to wait any longer.

This fixes the "TXTIME abs" failures on debug kernels, like:

Case ICMPv4 - TXTIME abs returned '', expected 'OK'

Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20240510005705.43069-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/testing/selftests/net/cmsg_sender.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/net/cmsg_sender.c b/tools/testing/selftests/net/cmsg_sender.c
index c79e65581dc37..161db24e3c409 100644
--- a/tools/testing/selftests/net/cmsg_sender.c
+++ b/tools/testing/selftests/net/cmsg_sender.c
@@ -333,16 +333,17 @@ static const char *cs_ts_info2str(unsigned int info)
return "unknown";
}

-static void
+static unsigned long
cs_read_cmsg(int fd, struct msghdr *msg, char *cbuf, size_t cbuf_sz)
{
struct sock_extended_err *see;
struct scm_timestamping *ts;
+ unsigned long ts_seen = 0;
struct cmsghdr *cmsg;
int i, err;

if (!opt.ts.ena)
- return;
+ return 0;
msg->msg_control = cbuf;
msg->msg_controllen = cbuf_sz;

@@ -396,8 +397,11 @@ cs_read_cmsg(int fd, struct msghdr *msg, char *cbuf, size_t cbuf_sz)
printf(" %5s ts%d %lluus\n",
cs_ts_info2str(see->ee_info),
i, rel_time);
+ ts_seen |= 1 << see->ee_info;
}
}
+
+ return ts_seen;
}

static void ca_set_sockopts(int fd)
@@ -509,10 +513,16 @@ int main(int argc, char *argv[])
err = ERN_SUCCESS;

if (opt.ts.ena) {
- /* Make sure all timestamps have time to loop back */
- usleep(opt.txtime.delay);
+ unsigned long seen;
+ int i;

- cs_read_cmsg(fd, &msg, cbuf, sizeof(cbuf));
+ /* Make sure all timestamps have time to loop back */
+ for (i = 0; i < 40; i++) {
+ seen = cs_read_cmsg(fd, &msg, cbuf, sizeof(cbuf));
+ if (seen & (1 << SCM_TSTAMP_SND))
+ break;
+ usleep(opt.txtime.delay / 20);
+ }
}

err_out:
--
2.43.0