Patch "selftests: net: fix timestamp not arriving in cmsg_time.sh" has been added to the 6.9-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    selftests: net: fix timestamp not arriving in cmsg_time.sh

to the 6.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     selftests-net-fix-timestamp-not-arriving-in-cmsg_tim.patch
and it can be found in the queue-6.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 5b150f5c3c0720deb7ead7ce2d524ddc47985ac1
Author: Jakub Kicinski <kuba@xxxxxxxxxx>
Date:   Thu May 9 17:57:04 2024 -0700

    selftests: net: fix timestamp not arriving in cmsg_time.sh
    
    [ 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@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20240510005705.43069-1-kuba@xxxxxxxxxx
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

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: