[PATCH] selftests/net: fin_ack_lat: fix latency threshold typo

[PATCH] selftests/net: fin_ack_lat: fix latency threshold typo

[Brian Grech]

The FIN-ACK latency threshold was written as 100000 (100ms) instead
of the intended 1000000 (1 second). Connections completing between
100ms and 1 second were incorrectly flagged as high-latency outliers
and printed as failures on loaded systems.

Add the missing zero to restore the intended 1 second threshold.

Signed-off-by: Brian Grech <bgrech@redhat.com>
---
 tools/testing/selftests/net/fin_ack_lat.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/fin_ack_lat.c b/tools/testing/selftests/net/fin_ack_lat.c
index 70187494b57a..4117332eb1a9 100644
--- a/tools/testing/selftests/net/fin_ack_lat.c
+++ b/tools/testing/selftests/net/fin_ack_lat.c
@@ -69,7 +69,7 @@ static void client(int port)
 		lat = timediff(start, end);
 		sum_lat += lat;
 		nr_lat++;
-		if (lat < 100000)
+		if (lat < 1000000)
 			goto close;
 
 		if (getsockname(sock, (struct sockaddr *)&laddr, &len) == -1)
-- 
2.55.0

[PATCH] selftests/net: fin_ack_lat: fix latency threshold typo

[Brian Grech]

The FIN-ACK latency threshold was written as 100000 (100ms) instead
of the intended 1000000 (1 second). Connections completing between
100ms and 1 second were incorrectly flagged as high-latency outliers
and printed as failures on loaded systems.

Add the missing zero to restore the intended 1 second threshold.

Signed-off-by: Brian Grech <bgrech@redhat.com>
---
v2: Added missing maintainer CCs

 tools/testing/selftests/net/fin_ack_lat.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/fin_ack_lat.c b/tools/testing/selftests/net/fin_ack_lat.c
index 70187494b57a..4117332eb1a9 100644
--- a/tools/testing/selftests/net/fin_ack_lat.c
+++ b/tools/testing/selftests/net/fin_ack_lat.c
@@ -69,7 +69,7 @@ static void client(int port)
 		lat = timediff(start, end);
 		sum_lat += lat;
 		nr_lat++;
-		if (lat < 100000)
+		if (lat < 1000000)
 			goto close;
 
 		if (getsockname(sock, (struct sockaddr *)&laddr, &len) == -1)
-- 
2.55.0

Re: [PATCH] selftests/net: fin_ack_lat: fix latency threshold typo

[Simon Horman]

On Tue, Aug 04, 2026 at 05:01:08PM -0500, Brian Grech wrote:
> The FIN-ACK latency threshold was written as 100000 (100ms) instead
> of the intended 1000000 (1 second). Connections completing between
> 100ms and 1 second were incorrectly flagged as high-latency outliers
> and printed as failures on loaded systems.
> 
> Add the missing zero to restore the intended 1 second threshold.
> 
> Signed-off-by: Brian Grech <bgrech@redhat.com>
> ---
> v2: Added missing maintainer CCs

Hi Brian,

It might be nice to include some information on why 1s is intended.
But I don't think that is strictly necessary.

Also, if this is a fix to be backported (I am unsure) then
it should have a Fixes tag and be targeted at the net branch.

The above notwithstanding, this looks good to me.

Reviewed-by: Simon Horman <horms@kernel.org>

Re: [PATCH] selftests/net: fin_ack_lat: fix latency threshold typo

[Brian Grech]

Hi Simon,

Thank you, yes I can fixup the message and resubmit.


On Thu, Aug 6, 2026 at 8:31 AM Simon Horman <horms@kernel.org> wrote:
>
> On Tue, Aug 04, 2026 at 05:01:08PM -0500, Brian Grech wrote:
> > The FIN-ACK latency threshold was written as 100000 (100ms) instead
> > of the intended 1000000 (1 second). Connections completing between
> > 100ms and 1 second were incorrectly flagged as high-latency outliers
> > and printed as failures on loaded systems.
> >
> > Add the missing zero to restore the intended 1 second threshold.
> >
> > Signed-off-by: Brian Grech <bgrech@redhat.com>
> > ---
> > v2: Added missing maintainer CCs
>
> Hi Brian,
>
> It might be nice to include some information on why 1s is intended.
> But I don't think that is strictly necessary.
>
> Also, if this is a fix to be backported (I am unsure) then
> it should have a Fixes tag and be targeted at the net branch.
>
> The above notwithstanding, this looks good to me.
>
> Reviewed-by: Simon Horman <horms@kernel.org>
>


-- 

-Brian

[PATCH net v3] selftests/net: fin_ack_lat: fix latency threshold typo

[Brian Grech]

The commit message for af8c8a450bf4 ("selftests: net: Add FIN_ACK
processing order related latency spike test") states: "if the latency
is larger than 1 second (spike), print a message". However the code
uses a threshold of 100000 us (100 ms), not 1000000 us (1 s).

The lower threshold causes false positives on slower hardware where
normal connection latency occasionally exceeds 100 ms but never
approaches the 1 s spike that indicates the actual FIN/ACK race bug.

Fix the threshold to match the documented intent.

Fixes: af8c8a450bf4 ("selftests: net: Add FIN_ACK processing order related latency spike test")
Cc: stable@vger.kernel.org
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Brian Grech <bgrech@redhat.com>
---
v3: Added Fixes tag, referenced original commit message wording per reviewer feedback
v2: Added missing maintainer CCs

 tools/testing/selftests/net/fin_ack_lat.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/fin_ack_lat.c b/tools/testing/selftests/net/fin_ack_lat.c
index 70187494b57a..4117332eb1a9 100644
--- a/tools/testing/selftests/net/fin_ack_lat.c
+++ b/tools/testing/selftests/net/fin_ack_lat.c
@@ -69,7 +69,7 @@ static void client(int port)
 		lat = timediff(start, end);
 		sum_lat += lat;
 		nr_lat++;
-		if (lat < 100000)
+		if (lat < 1000000)
 			goto close;
 
 		if (getsockname(sock, (struct sockaddr *)&laddr, &len) == -1)
-- 
2.55.0