[PATCH net] selftests: iou-zcrx: defer listen() until after zcrx setup

[PATCH net] selftests: iou-zcrx: defer listen() until after zcrx setup

[Dragos Tatulea]

The server binds the queues for zero-copy after listen(). If the client
does a connect() during this time it can fail with EHOSTUNREACH on
a cold system. This was encountered with the mlx5 driver where binding
the .ndo_queue_start() is a slow operation during which no packets
can be exchanged.

This change moves listen() after queue binding, when the test server is
fully operational.

Fixes: 71082faa2c64 ("io_uring/zcrx: add selftest")
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Cosmin Ratiu <cratiu@nvidia.com>
---
 tools/testing/selftests/drivers/net/hw/iou-zcrx.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/drivers/net/hw/iou-zcrx.c b/tools/testing/selftests/drivers/net/hw/iou-zcrx.c
index 240d13dbc54e..f6a8fc5fac24 100644
--- a/tools/testing/selftests/drivers/net/hw/iou-zcrx.c
+++ b/tools/testing/selftests/drivers/net/hw/iou-zcrx.c
@@ -351,9 +351,6 @@ static void run_server(void)
 	if (ret < 0)
 		error(1, 0, "bind()");
 
-	if (listen(fd, 1024) < 0)
-		error(1, 0, "listen()");
-
 	flags |= IORING_SETUP_COOP_TASKRUN;
 	flags |= IORING_SETUP_SINGLE_ISSUER;
 	flags |= IORING_SETUP_DEFER_TASKRUN;
@@ -366,6 +363,9 @@ static void run_server(void)
 	if (cfg_dry_run)
 		return;
 
+	if (listen(fd, 1024) < 0)
+		error(1, 0, "listen()");
+
 	add_accept(&ring, fd);
 
 	tstop = gettimeofday_ms() + 5000;
-- 
2.54.0

Re: [PATCH net] selftests: iou-zcrx: defer listen() until after zcrx setup

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 11 Jun 2026 19:03:41 +0300 you wrote:
> The server binds the queues for zero-copy after listen(). If the client
> does a connect() during this time it can fail with EHOSTUNREACH on
> a cold system. This was encountered with the mlx5 driver where binding
> the .ndo_queue_start() is a slow operation during which no packets
> can be exchanged.
> 
> This change moves listen() after queue binding, when the test server is
> fully operational.
> 
> [...]

Here is the summary with links:
  - [net] selftests: iou-zcrx: defer listen() until after zcrx setup
    https://git.kernel.org/netdev/net-next/c/ec782be97d2d

You are awesome, thank you!
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