linux-kernel - [PATCH 4.14 065/164] iwlwifi: mvm: dont use transmit queue hang detection when it is not possible

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Date:   Tue, 12 Dec 2017 13:44:05 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Emmanuel Grumbach <emmanuel.grumbach@...el.com>,
        Luca Coelho <luciano.coelho@...el.com>
Subject: [PATCH 4.14 065/164] iwlwifi: mvm: dont use transmit queue hang detection when it is not possible

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Emmanuel Grumbach <emmanuel.grumbach@...el.com>

commit 0b9832b712d6767d6c7b01965fd788d1ca84fc92 upstream.

When we act as an AP, new firmware versions handle
internally the power saving clients and the driver doesn't
know that the peers went to sleep. It is, hence, possible
that a peer goes to sleep for a long time and stop pulling
frames. This will cause its transmit queue to hang which is
a condition that triggers the recovery flow in the driver.

While this client is certainly buggy (it should have pulled
the frame based on the TIM IE in the beacon), we can't blow
up because of a buggy client.

Change the current implementation to not enable the
transmit queue hang detection on queues that serve peers
when we act as an AP / GO.

We can still enable this mechanism using the debug
configuration which can come in handy when we want to
debug why the client doesn't wake up.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@...el.com>
Signed-off-by: Luca Coelho <luciano.coelho@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/wireless/intel/iwlwifi/mvm/utils.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

--- a/drivers/net/wireless/intel/iwlwifi/mvm/utils.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/utils.c
@@ -1143,9 +1143,18 @@ unsigned int iwl_mvm_get_wd_timeout(stru
 	unsigned int default_timeout =
 		cmd_q ? IWL_DEF_WD_TIMEOUT : mvm->cfg->base_params->wd_timeout;

-	if (!iwl_fw_dbg_trigger_enabled(mvm->fw, FW_DBG_TRIGGER_TXQ_TIMERS))
+	if (!iwl_fw_dbg_trigger_enabled(mvm->fw, FW_DBG_TRIGGER_TXQ_TIMERS)) {
+		/*
+		 * We can't know when the station is asleep or awake, so we
+		 * must disable the queue hang detection.
+		 */
+		if (fw_has_capa(&mvm->fw->ucode_capa,
+				IWL_UCODE_TLV_CAPA_STA_PM_NOTIF) &&
+		    vif && vif->type == NL80211_IFTYPE_AP)
+			return IWL_WATCHDOG_DISABLED;
 		return iwlmvm_mod_params.tfd_q_hang_detect ?
 			default_timeout : IWL_WATCHDOG_DISABLED;
+	}

 	trigger = iwl_fw_dbg_get_trigger(mvm->fw, FW_DBG_TRIGGER_TXQ_TIMERS);
 	txq_timer = (void *)trigger->data;