[PATCH] wifi: iwlwifi: mld: stop mac80211 TX queues on firmware error

[Cole Leavitt <cole@unwrap.rs>]

When firmware encounters an error in the iwlmld driver, nothing prevents
mac80211 from continuing to feed TX packets. The mvm driver uses atomic
status bits (IWL_MVM_STATUS_HW_RESTART_REQUESTED) checked in its TX path
to gate transmissions, but the mld driver has no equivalent check --
iwl_mld_tx_from_txq() only checks mld_txq->status.stop_full.

This allows TX to proceed while firmware is unresponsive, causing
spinlock contention and soft lockups lasting 22-26 seconds.

Add ieee80211_stop_queues() in both iwl_mld_nic_error() and
iwl_mld_sw_reset() to stop TX at the mac80211 level when a restart will
follow, and add the corresponding ieee80211_wake_queues() in
iwl_mld_restart_cleanup() to resume TX after recovery.

The stop in iwl_mld_nic_error() is placed inside the conditional that
sets in_hw_restart to ensure queues are only stopped when a restart will
actually follow, avoiding a permanent TX stall on error paths where no
restart occurs (e.g. IWL_ERR_TYPE_RESET_HS_TIMEOUT with
!fw_status.running). The stop in iwl_mld_sw_reset() is unconditional
since that path always sets in_hw_restart.

Tested on ThinkPad P16 Gen3 with Intel BE200 (WiFi7) running kernel
6.19.0-rc8.

Fixes: d1e879ec600f ("wifi: iwlwifi: add iwlmld sub-driver")
Cc: stable@vger.kernel.org
Signed-off-by: Cole Leavitt <cole@unwrap.rs>
---
 drivers/net/wireless/intel/iwlwifi/mld/mac80211.c | 2 ++
 drivers/net/wireless/intel/iwlwifi/mld/mld.c      | 5 ++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/mld/mac80211.c b/drivers/net/wireless/intel/iwlwifi/mld/mac80211.c
index df8221277d51..552888538e16 100644
--- a/drivers/net/wireless/intel/iwlwifi/mld/mac80211.c
+++ b/drivers/net/wireless/intel/iwlwifi/mld/mac80211.c
@@ -558,6 +558,8 @@ iwl_mld_restart_cleanup(struct iwl_mld *mld)
 					  iwl_mld_cleanup_sta, NULL);
 
 	iwl_mld_ftm_restart_cleanup(mld);
+
+	ieee80211_wake_queues(mld->hw);
 }
 
 static
diff --git a/drivers/net/wireless/intel/iwlwifi/mld/mld.c b/drivers/net/wireless/intel/iwlwifi/mld/mld.c
index 495e9d8f3af6..ed44c10c08a1 100644
--- a/drivers/net/wireless/intel/iwlwifi/mld/mld.c
+++ b/drivers/net/wireless/intel/iwlwifi/mld/mld.c
@@ -672,8 +672,10 @@ iwl_mld_nic_error(struct iwl_op_mode *op_mode,
 	 * setting doesn't matter if we're going to be unbound either.
 	 */
 	if (type != IWL_ERR_TYPE_RESET_HS_TIMEOUT &&
-	    mld->fw_status.running)
+	    mld->fw_status.running) {
+		ieee80211_stop_queues(mld->hw);
 		mld->fw_status.in_hw_restart = true;
+	}
 }
 
 static void iwl_mld_dump_error(struct iwl_op_mode *op_mode,
@@ -703,6 +705,7 @@ static bool iwl_mld_sw_reset(struct iwl_op_mode *op_mode,
 	 * had a NIC error both were already done.
 	 */
 	iwl_mld_report_scan_aborted(mld);
+	ieee80211_stop_queues(mld->hw);
 	mld->fw_status.in_hw_restart = true;
 
 	/* Do restart only in the following conditions are met:

base-commit: 66af8ac52d10ea229d5755b8700e2fe86fc037f7
-- 
2.52.0