[PATCH net v1] net/mlx5e: kTLS, Fix missing error unwind when enabling RX offload

[Xuanqiang Luo <xuanqiang.luo@linux.dev>]

From: Xuanqiang Luo <luoxuanqiang@kylinos.cn>

Since commit abed42f9cd80 ("net/mlx5e: Conditionally create async
ICOSQ"), the async ICOSQ is only created when an XDP program is attached
or priv->ktls_rx_was_enabled is set. When TLS RX offload is enabled for
the first time, mlx5e_ktls_set_feature_rx() sets the flag and reopens
the channels so that they get the queue, but it ignores the return value
of mlx5e_safe_reopen_channels().

If the reopen fails, mlx5e_safe_switch_params() keeps the old channels,
which have no async ICOSQ, while NETIF_F_HW_TLS_RX is still reported as
enabled. The next offloaded RX connection then dereferences the NULL
c->async_icosq in post_rx_param_wqes(). Enabling the feature again does
not help, as the flag is already set and the reopen is skipped.

Propagate the error, clear the flag and destroy the accel TCP flow
tables again, so that the feature stays disabled and the next attempt
retries the reopen.

Fixes: abed42f9cd80 ("net/mlx5e: Conditionally create async ICOSQ")
Signed-off-by: Xuanqiang Luo <luoxuanqiang@kylinos.cn>
---
Found by code inspection while backporting commit abed42f9cd80 to a
downstream kernel. I do not have a crypto-enabled ConnectX NIC, so the
failure has not been reproduced and the fix is only compile-tested.

The crash itself is the one described in the changelog of abed42f9cd80
("async ICOSQ allocation is not triggered, causing a NULL pointer
crash"). This patch only covers the case where the reopen that should
create the queue fails. ktls.c is also the only caller that ignores the
return value of mlx5e_safe_reopen_channels(); the callers in health.c
and reporter_tx.c check it.

 drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls.c b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls.c
index 337201f128958..3cc1213c2f682 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls.c
@@ -139,7 +139,11 @@ int mlx5e_ktls_set_feature_rx(struct net_device *netdev, bool enable)
 		err = mlx5e_accel_fs_tcp_create(priv->fs);
 		if (!err && !priv->ktls_rx_was_enabled) {
 			priv->ktls_rx_was_enabled = true;
-			mlx5e_safe_reopen_channels(priv);
+			err = mlx5e_safe_reopen_channels(priv);
+			if (err) {
+				priv->ktls_rx_was_enabled = false;
+				mlx5e_accel_fs_tcp_destroy(priv->fs);
+			}
 		}
 	} else {
 		mlx5e_accel_fs_tcp_destroy(priv->fs);
-- 
2.43.0