Re: [PATCH iwl-net 3/3] ice: do not block on the aux device lock in ndo_setup_tc

On 10/21/26 1:22 PM, Loktionov, Aleksandr wrote:

quoted

-----Original Message-----
From: Petr Oros <redacted>
Sent: Monday, October 19, 2026 8:53 AM
To: netdev@vger.kernel.org
Cc: Oros, Petr <redacted>; Nguyen, Anthony L
[off-list ref]; Kitszel, Przemyslaw
[off-list ref]; Andrew Lunn [off-list ref];
David S . Miller [off-list ref]; Eric Dumazet
[off-list ref]; Jakub Kicinski [off-list ref]; Paolo Abeni
[off-list ref]; Ertman, David M [off-list ref]; Shiraz
Saleem [off-list ref]; Leon Romanovsky [off-list ref];
Maziarz, Kamil [off-list ref]; Rafal Rogalski
[off-list ref]; Loktionov, Aleksandr
[off-list ref]; Schmidt, Michal [off-list ref];
linux-rdma@vger.kernel.org; intel-wired-lan@lists.osuosl.org; linux-
kernel@vger.kernel.org; stable@vger.kernel.org; Sebastian Andrzej
Siewior [off-list ref]; Clark Williams [off-list ref];
Steven Rostedt [off-list ref]; Mateusz Palczewski
[off-list ref]; linux-rt-devel@lists.linux.dev
Subject: [PATCH iwl-net 3/3] ice: do not block on the aux device lock in
ndo_setup_tc

The TC_SETUP_QDISC_MQPRIO path of ice_setup_tc() takes the auxiliary
device lock to test whether the RDMA driver is bound, and ndo_setup_tc()
runs with the RTNL lock held. This closes the same cycle against the
RDMA auxiliary probe as the two preceding patches.

Use device_trylock() and report the device as busy when it fails, with a
distinct message for the same reason as in the previous patch.

Fixes: 4b31fd4d77ff ("ice: Fix RDMA VSI removal during queue rebuild")
Cc: stable@vger.kernel.org
Signed-off-by: Petr Oros <redacted>
---
  drivers/net/ethernet/intel/ice/ice_main.c | 6 +++++-
  1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_main.c

b/drivers/net/ethernet/intel/ice/ice_main.c
index edb62606d2aae3..7b251136149615 100644

--- a/drivers/net/ethernet/intel/ice/ice_main.c
+++ b/drivers/net/ethernet/intel/ice/ice_main.c

@@ -9448,7 +9448,11 @@ ice_setup_tc(struct net_device *netdev, enum

tc_setup_type type,
  		cdev = pf->cdev_info;
  		if (cdev && cdev->adev) {
  			mutex_lock(&pf->adev_mutex);
-			device_lock(&cdev->adev->dev);
+			if (!device_trylock(&cdev->adev->dev)) {
+				mutex_unlock(&pf->adev_mutex);
+				netdev_dbg(netdev, "RDMA auxiliary device is
busy, try again\n");
+				return -EBUSY;

You return error here, but it looks like being silently dropped in mqprio_disable_offload() isn't it ?

Yes, mqprio_disable_offload() ignores it, the same as it ignores the
existing -EBUSY for a bound RDMA driver. Blocking there brings the
deadlock back and skipping the lock races with the probe, so v2 keeps
the refusal and warns about it instead of netdev_dbg().

quoted

+			}
  			locked = true;
  			if (cdev->adev->dev.driver) {
  				netdev_err(netdev, "Cannot change qdisc when
RDMA is active\n");
--
2.56.0