iwlwifi: Recover TX flow stall due to stuck queue

Monitors the internal TX queues periodically.  When a queue is stuck
for some unknown conditions causing the throughput to drop and the
transfer is stop, the driver will force firmware reload and bring the
system back to normal operational state.

The iwlwifi devices behave differently in this regard so this feature is
made part of the ops infrastructure so we can have more control on how to
monitor and recover from tx queue stall case per device.

Signed-off-by: Trieu 'Andrew' Nguyen <trieux.t.nguyen@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>

diff --git a/drivers/net/wireless/iwlwifi/iwl-1000.c b/drivers/net/wireless/iwlwifi/iwl-1000.c
index e31e8a3459b5269cad6c16f0f40872ac43364118..5a9cb70160f6f24d0ce1a7132ebab65d9774fb35 100644 (file)
--- a/drivers/net/wireless/iwlwifi/iwl-1000.c
+++ b/drivers/net/wireless/iwlwifi/iwl-1000.c
@@ -212,6 +212,7 @@ static struct iwl_lib_ops iwl1000_lib = {
                .set_ct_kill = iwl1000_set_ct_threshold,
         },
        .add_bcast_station = iwl_add_bcast_station,
+       .recover_from_tx_stall = iwl_bg_monitor_recover,
 };
 
 static const struct iwl_ops iwl1000_ops = {
@@ -249,6 +250,7 @@ struct iwl_cfg iwl1000_bgn_cfg = {
        .support_ct_kill_exit = true,
        .plcp_delta_threshold = IWL_MAX_PLCP_ERR_EXT_LONG_THRESHOLD_DEF,
        .chain_noise_scale = 1000,
+       .monitor_recover_period = IWL_MONITORING_PERIOD,
 };
 
 struct iwl_cfg iwl1000_bg_cfg = {
@@ -277,6 +279,7 @@ struct iwl_cfg iwl1000_bg_cfg = {
        .support_ct_kill_exit = true,
        .plcp_delta_threshold = IWL_MAX_PLCP_ERR_EXT_LONG_THRESHOLD_DEF,
        .chain_noise_scale = 1000,
+       .monitor_recover_period = IWL_MONITORING_PERIOD,
 };
 
 MODULE_FIRMWARE(IWL1000_MODULE_FIRMWARE(IWL1000_UCODE_API_MAX));

diff --git a/drivers/net/wireless/iwlwifi/iwl-3945.c b/drivers/net/wireless/iwlwifi/iwl-3945.c
index 11785e2c767a9e88209e7f5e1c2c3defae449d38..21ae61dd3d516a18155c970563b758cca9d3f2b8 100644 (file)
--- a/drivers/net/wireless/iwlwifi/iwl-3945.c
+++ b/drivers/net/wireless/iwlwifi/iwl-3945.c
@@ -2820,6 +2820,7 @@ static struct iwl_cfg iwl3945_bg_cfg = {
        .led_compensation = 64,
        .broken_powersave = true,
        .plcp_delta_threshold = IWL_MAX_PLCP_ERR_THRESHOLD_DEF,
+       .monitor_recover_period = IWL_MONITORING_PERIOD,
 };
 
 static struct iwl_cfg iwl3945_abg_cfg = {
@@ -2838,6 +2839,7 @@ static struct iwl_cfg iwl3945_abg_cfg = {
        .led_compensation = 64,
        .broken_powersave = true,
        .plcp_delta_threshold = IWL_MAX_PLCP_ERR_THRESHOLD_DEF,
+       .monitor_recover_period = IWL_MONITORING_PERIOD,
 };
 
 DEFINE_PCI_DEVICE_TABLE(iwl3945_hw_card_ids) = {

diff --git a/drivers/net/wireless/iwlwifi/iwl-4965.c b/drivers/net/wireless/iwlwifi/iwl-4965.c
index 7f9e448fe5e16f564cae1dc882b392b35a32c5fe..acca89a635a54bdc1020489eb35315fd980634c5 100644 (file)
--- a/drivers/net/wireless/iwlwifi/iwl-4965.c
+++ b/drivers/net/wireless/iwlwifi/iwl-4965.c
@@ -2255,6 +2255,7 @@ struct iwl_cfg iwl4965_agn_cfg = {
        .led_compensation = 61,
        .chain_noise_num_beacons = IWL4965_CAL_NUM_BEACONS,
        .plcp_delta_threshold = IWL_MAX_PLCP_ERR_THRESHOLD_DEF,
+       .monitor_recover_period = IWL_MONITORING_PERIOD,
 };
 
 /* Module firmware */

diff --git a/drivers/net/wireless/iwlwifi/iwl-5000.c b/drivers/net/wireless/iwlwifi/iwl-5000.c
index 8ab28a76015785a6f99748dbc7e0a89b3d4e86d3..a01b3c59a5a7445698cd01ebdd9e47887eb9529f 100644 (file)
--- a/drivers/net/wireless/iwlwifi/iwl-5000.c
+++ b/drivers/net/wireless/iwlwifi/iwl-5000.c
@@ -1499,6 +1499,7 @@ struct iwl_lib_ops iwl5000_lib = {
                .set_ct_kill = iwl5000_set_ct_threshold,
         },
        .add_bcast_station = iwl_add_bcast_station,
+       .recover_from_tx_stall = iwl_bg_monitor_recover,
 };
 
 static struct iwl_lib_ops iwl5150_lib = {
@@ -1553,6 +1554,7 @@ static struct iwl_lib_ops iwl5150_lib = {
                .set_ct_kill = iwl5150_set_ct_threshold,
         },
        .add_bcast_station = iwl_add_bcast_station,
+       .recover_from_tx_stall = iwl_bg_monitor_recover,
 };
 
 static const struct iwl_ops iwl5000_ops = {
@@ -1602,6 +1604,7 @@ struct iwl_cfg iwl5300_agn_cfg = {
        .chain_noise_num_beacons = IWL_CAL_NUM_BEACONS,
        .plcp_delta_threshold = IWL_MAX_PLCP_ERR_LONG_THRESHOLD_DEF,
        .chain_noise_scale = 1000,
+       .monitor_recover_period = IWL_MONITORING_PERIOD,
 };
 
 struct iwl_cfg iwl5100_bgn_cfg = {
@@ -1628,6 +1631,7 @@ struct iwl_cfg iwl5100_bgn_cfg = {
        .chain_noise_num_beacons = IWL_CAL_NUM_BEACONS,
        .plcp_delta_threshold = IWL_MAX_PLCP_ERR_LONG_THRESHOLD_DEF,
        .chain_noise_scale = 1000,
+       .monitor_recover_period = IWL_MONITORING_PERIOD,
 };
 
 struct iwl_cfg iwl5100_abg_cfg = {
@@ -1652,6 +1656,7 @@ struct iwl_cfg iwl5100_abg_cfg = {
        .chain_noise_num_beacons = IWL_CAL_NUM_BEACONS,
        .plcp_delta_threshold = IWL_MAX_PLCP_ERR_LONG_THRESHOLD_DEF,
        .chain_noise_scale = 1000,
+       .monitor_recover_period = IWL_MONITORING_PERIOD,
 };
 
 struct iwl_cfg iwl5100_agn_cfg = {
@@ -1678,6 +1683,7 @@ struct iwl_cfg iwl5100_agn_cfg = {
        .chain_noise_num_beacons = IWL_CAL_NUM_BEACONS,
        .plcp_delta_threshold = IWL_MAX_PLCP_ERR_LONG_THRESHOLD_DEF,
        .chain_noise_scale = 1000,
+       .monitor_recover_period = IWL_MONITORING_PERIOD,
 };
 
 struct iwl_cfg iwl5350_agn_cfg = {
@@ -1704,6 +1710,7 @@ struct iwl_cfg iwl5350_agn_cfg = {
        .chain_noise_num_beacons = IWL_CAL_NUM_BEACONS,
        .plcp_delta_threshold = IWL_MAX_PLCP_ERR_LONG_THRESHOLD_DEF,
        .chain_noise_scale = 1000,
+       .monitor_recover_period = IWL_MONITORING_PERIOD,
 };
 
 struct iwl_cfg iwl5150_agn_cfg = {
@@ -1730,6 +1737,7 @@ struct iwl_cfg iwl5150_agn_cfg = {
        .chain_noise_num_beacons = IWL_CAL_NUM_BEACONS,
        .plcp_delta_threshold = IWL_MAX_PLCP_ERR_LONG_THRESHOLD_DEF,
        .chain_noise_scale = 1000,
+       .monitor_recover_period = IWL_MONITORING_PERIOD,
 };
 
 struct iwl_cfg iwl5150_abg_cfg = {
@@ -1754,6 +1762,7 @@ struct iwl_cfg iwl5150_abg_cfg = {
        .chain_noise_num_beacons = IWL_CAL_NUM_BEACONS,
        .plcp_delta_threshold = IWL_MAX_PLCP_ERR_LONG_THRESHOLD_DEF,
        .chain_noise_scale = 1000,
+       .monitor_recover_period = IWL_MONITORING_PERIOD,
 };
 
 MODULE_FIRMWARE(IWL5000_MODULE_FIRMWARE(IWL5000_UCODE_API_MAX));

diff --git a/drivers/net/wireless/iwlwifi/iwl-6000.c b/drivers/net/wireless/iwlwifi/iwl-6000.c
index fb7012289c3d2e561c23ffc6dfae8ec4f126beae..4fbc38cfd9112288b2541955b7906958bb4b5fac 100644 (file)
--- a/drivers/net/wireless/iwlwifi/iwl-6000.c
+++ b/drivers/net/wireless/iwlwifi/iwl-6000.c
@@ -278,6 +278,7 @@ static struct iwl_lib_ops iwl6000_lib = {
                .set_ct_kill = iwl6000_set_ct_threshold,
         },
        .add_bcast_station = iwl_add_bcast_station,
+       .recover_from_tx_stall = iwl_bg_monitor_recover,
 };
 
 static const struct iwl_ops iwl6000_ops = {
@@ -343,6 +344,7 @@ static struct iwl_lib_ops iwl6050_lib = {
                .set_calib_version = iwl6050_set_calib_version,
         },
        .add_bcast_station = iwl_add_bcast_station,
+       .recover_from_tx_stall = iwl_bg_monitor_recover,
 };
 
 static const struct iwl_ops iwl6050_ops = {
@@ -386,6 +388,7 @@ struct iwl_cfg iwl6000i_2agn_cfg = {
        .support_ct_kill_exit = true,
        .plcp_delta_threshold = IWL_MAX_PLCP_ERR_THRESHOLD_DEF,
        .chain_noise_scale = 1000,
+       .monitor_recover_period = IWL_MONITORING_PERIOD,
 };
 
 struct iwl_cfg iwl6000i_2abg_cfg = {
@@ -417,6 +420,7 @@ struct iwl_cfg iwl6000i_2abg_cfg = {
        .support_ct_kill_exit = true,
        .plcp_delta_threshold = IWL_MAX_PLCP_ERR_THRESHOLD_DEF,
        .chain_noise_scale = 1000,
+       .monitor_recover_period = IWL_MONITORING_PERIOD,
 };
 
 struct iwl_cfg iwl6000i_2bg_cfg = {
@@ -448,6 +452,7 @@ struct iwl_cfg iwl6000i_2bg_cfg = {
        .support_ct_kill_exit = true,
        .plcp_delta_threshold = IWL_MAX_PLCP_ERR_THRESHOLD_DEF,
        .chain_noise_scale = 1000,
+       .monitor_recover_period = IWL_MONITORING_PERIOD,
 };
 
 struct iwl_cfg iwl6050_2agn_cfg = {
@@ -480,6 +485,7 @@ struct iwl_cfg iwl6050_2agn_cfg = {
        .support_ct_kill_exit = true,
        .plcp_delta_threshold = IWL_MAX_PLCP_ERR_THRESHOLD_DEF,
        .chain_noise_scale = 1500,
+       .monitor_recover_period = IWL_MONITORING_PERIOD,
 };
 
 struct iwl_cfg iwl6050_2abg_cfg = {
@@ -511,6 +517,7 @@ struct iwl_cfg iwl6050_2abg_cfg = {
        .support_ct_kill_exit = true,
        .plcp_delta_threshold = IWL_MAX_PLCP_ERR_THRESHOLD_DEF,
        .chain_noise_scale = 1500,
+       .monitor_recover_period = IWL_MONITORING_PERIOD,
 };
 
 struct iwl_cfg iwl6000_3agn_cfg = {
@@ -543,6 +550,7 @@ struct iwl_cfg iwl6000_3agn_cfg = {
        .support_ct_kill_exit = true,
        .plcp_delta_threshold = IWL_MAX_PLCP_ERR_THRESHOLD_DEF,
        .chain_noise_scale = 1000,
+       .monitor_recover_period = IWL_MONITORING_PERIOD,
 };
 
 MODULE_FIRMWARE(IWL6000_MODULE_FIRMWARE(IWL6000_UCODE_API_MAX));

diff --git a/drivers/net/wireless/iwlwifi/iwl-agn.c b/drivers/net/wireless/iwlwifi/iwl-agn.c
index 93931b61304bcd9b9da565b49e5fa1aa206d6a96..82b1a3fb54ef133cb609b8d39efbd1e91a2272d5 100644 (file)
--- a/drivers/net/wireless/iwlwifi/iwl-agn.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn.c
@@ -2074,6 +2074,13 @@ static void iwl_alive_start(struct iwl_priv *priv)
        /* After the ALIVE response, we can send host commands to the uCode */
        set_bit(STATUS_ALIVE, &priv->status);
 
+       if (priv->cfg->ops->lib->recover_from_tx_stall) {
+               /* Enable timer to monitor the driver queues */
+               mod_timer(&priv->monitor_recover,
+                       jiffies +
+                       msecs_to_jiffies(priv->cfg->monitor_recover_period));
+       }
+
        if (iwl_is_rfkill(priv))
                return;
 
@@ -3224,6 +3231,13 @@ static void iwl_setup_deferred_work(struct iwl_priv *priv)
        priv->ucode_trace.data = (unsigned long)priv;
        priv->ucode_trace.function = iwl_bg_ucode_trace;
 
+       if (priv->cfg->ops->lib->recover_from_tx_stall) {
+               init_timer(&priv->monitor_recover);
+               priv->monitor_recover.data = (unsigned long)priv;
+               priv->monitor_recover.function =
+                       priv->cfg->ops->lib->recover_from_tx_stall;
+       }
+
        if (!priv->cfg->use_isr_legacy)
                tasklet_init(&priv->irq_tasklet, (void (*)(unsigned long))
                        iwl_irq_tasklet, (unsigned long)priv);
@@ -3243,6 +3257,8 @@ static void iwl_cancel_deferred_work(struct iwl_priv *priv)
        cancel_work_sync(&priv->beacon_update);
        del_timer_sync(&priv->statistics_periodic);
        del_timer_sync(&priv->ucode_trace);
+       if (priv->cfg->ops->lib->recover_from_tx_stall)
+               del_timer_sync(&priv->monitor_recover);
 }
 
 static void iwl_init_hw_rates(struct iwl_priv *priv,

diff --git a/drivers/net/wireless/iwlwifi/iwl-core.c b/drivers/net/wireless/iwlwifi/iwl-core.c
index d4c2a3e17c537efe09d14d79d5fef37ce7e21b4d..5180fb24cd3896b405b556c46148e45cc008a431 100644 (file)
--- a/drivers/net/wireless/iwlwifi/iwl-core.c
+++ b/drivers/net/wireless/iwlwifi/iwl-core.c
@@ -3051,6 +3051,99 @@ int iwl_force_reset(struct iwl_priv *priv, int mode)
        }
        return 0;
 }
+EXPORT_SYMBOL(iwl_force_reset);
+
+/**
+ * iwl_bg_monitor_recover - Timer callback to check for stuck queue and recover
+ *
+ * During normal condition (no queue is stuck), the timer is continually set to
+ * execute every monitor_recover_period milliseconds after the last timer
+ * expired.  When the queue read_ptr is at the same place, the timer is
+ * shorten to 100mSecs.  This is
+ *      1) to reduce the chance that the read_ptr may wrap around (not stuck)
+ *      2) to detect the stuck queues quicker before the station and AP can
+ *      disassociate each other.
+ *
+ * This function monitors all the tx queues and recover from it if any
+ * of the queues are stuck.
+ * 1. It first check the cmd queue for stuck conditions.  If it is stuck,
+ *      it will recover by resetting the firmware and return.
+ * 2. Then, it checks for station association.  If it associates it will check
+ *      other queues.  If any queue is stuck, it will recover by resetting
+ *      the firmware.
+ * Note: It the number of times the queue read_ptr to be at the same place to
+ *      be MAX_REPEAT+1 in order to consider to be stuck.
+ */
+/*
+ * The maximum number of times the read pointer of the tx queue at the
+ * same place without considering to be stuck.
+ */
+#define MAX_REPEAT      (2)
+static int iwl_check_stuck_queue(struct iwl_priv *priv, int cnt)
+{
+       struct iwl_tx_queue *txq;
+       struct iwl_queue *q;
+
+       txq = &priv->txq[cnt];
+       q = &txq->q;
+       /* queue is empty, skip */
+       if (q->read_ptr != q->write_ptr) {
+               if (q->read_ptr == q->last_read_ptr) {
+                       /* a queue has not been read from last time */
+                       if (q->repeat_same_read_ptr > MAX_REPEAT) {
+                               IWL_ERR(priv,
+                                       "queue %d stuck %d time. Fw reload.\n",
+                                       q->id, q->repeat_same_read_ptr);
+                               q->repeat_same_read_ptr = 0;
+                               iwl_force_reset(priv, IWL_FW_RESET);
+                       } else {
+                               q->repeat_same_read_ptr++;
+                               IWL_DEBUG_RADIO(priv,
+                                               "queue %d, not read %d time\n",
+                                               q->id,
+                                               q->repeat_same_read_ptr);
+                               mod_timer(&priv->monitor_recover, jiffies +
+                                       msecs_to_jiffies(IWL_ONE_HUNDRED_MSECS));
+                       }
+                       return 1;
+               } else {
+                       q->last_read_ptr = q->read_ptr;
+                       q->repeat_same_read_ptr = 0;
+               }
+       }
+       return 0;
+}
+
+void iwl_bg_monitor_recover(unsigned long data)
+{
+       struct iwl_priv *priv = (struct iwl_priv *)data;
+       int cnt;
+
+       if (test_bit(STATUS_EXIT_PENDING, &priv->status))
+               return;
+
+       /* monitor and check for stuck cmd queue */
+       if (iwl_check_stuck_queue(priv, IWL_CMD_QUEUE_NUM))
+               return;
+
+       /* monitor and check for other stuck queues */
+       if (iwl_is_associated(priv)) {
+               for (cnt = 0; cnt < priv->hw_params.max_txq_num; cnt++) {
+                       /* skip as we already checked the command queue */
+                       if (cnt == IWL_CMD_QUEUE_NUM)
+                               continue;
+                       if (iwl_check_stuck_queue(priv, cnt))
+                               return;
+               }
+       }
+       /*
+        * Reschedule the timer to occur in
+        * priv->cfg->monitor_recover_period
+        */
+       mod_timer(&priv->monitor_recover,
+               jiffies + msecs_to_jiffies(priv->cfg->monitor_recover_period));
+}
+EXPORT_SYMBOL(iwl_bg_monitor_recover);
 
 #ifdef CONFIG_PM
 

diff --git a/drivers/net/wireless/iwlwifi/iwl-core.h b/drivers/net/wireless/iwlwifi/iwl-core.h
index 2482a25d543f677dbee56d4d2425c3f24cf04295..c4cd1deb3b3eed9f03c8c7de8cbdc5c3752aeb97 100644 (file)
--- a/drivers/net/wireless/iwlwifi/iwl-core.h
+++ b/drivers/net/wireless/iwlwifi/iwl-core.h
@@ -191,6 +191,8 @@ struct iwl_lib_ops {
        struct iwl_temp_ops temp_ops;
        /* station management */
        void (*add_bcast_station)(struct iwl_priv *priv);
+       /* recover from tx queue stall */
+       void (*recover_from_tx_stall)(unsigned long data);
 };
 
 struct iwl_led_ops {
@@ -295,6 +297,8 @@ struct iwl_cfg {
        const bool support_wimax_coexist;
        u8 plcp_delta_threshold;
        s32 chain_noise_scale;
+       /* timer period for monitor the driver queues */
+       u32 monitor_recover_period;
 };
 
 /***************************
@@ -568,6 +572,9 @@ static inline u16 iwl_pcie_link_ctl(struct iwl_priv *priv)
        pci_read_config_word(priv->pci_dev, pos + PCI_EXP_LNKCTL, &pci_lnk_ctl);
        return pci_lnk_ctl;
 }
+
+void iwl_bg_monitor_recover(unsigned long data);
+
 #ifdef CONFIG_PM
 int iwl_pci_suspend(struct pci_dev *pdev, pm_message_t state);
 int iwl_pci_resume(struct pci_dev *pdev);

diff --git a/drivers/net/wireless/iwlwifi/iwl-dev.h b/drivers/net/wireless/iwlwifi/iwl-dev.h
index 9c676ea420b9aeabbc8dc87fd32a0eb651356620..bb4cba508acffb03b270f405a58af5fc62525617 100644 (file)
--- a/drivers/net/wireless/iwlwifi/iwl-dev.h
+++ b/drivers/net/wireless/iwlwifi/iwl-dev.h
@@ -183,6 +183,10 @@ struct iwl_queue {
        int n_bd;              /* number of BDs in this queue */
        int write_ptr;       /* 1-st empty entry (index) host_w*/
        int read_ptr;         /* last used entry (index) host_r*/
+       /* use for monitoring and recovering the stuck queue */
+       int last_read_ptr;      /* storing the last read_ptr */
+       /* number of time read_ptr and last_read_ptr are the same */
+       u8 repeat_same_read_ptr;
        dma_addr_t dma_addr;   /* physical addr for BD's */
        int n_window;          /* safe queue window */
        u32 id;
@@ -1044,6 +1048,11 @@ struct iwl_event_log {
 #define IWL_DELAY_NEXT_FORCE_RF_RESET  (HZ*3)
 #define IWL_DELAY_NEXT_FORCE_FW_RELOAD (HZ*5)
 
+/* timer constants use to monitor and recover stuck tx queues in mSecs */
+#define IWL_MONITORING_PERIOD  (1000)
+#define IWL_ONE_HUNDRED_MSECS   (100)
+#define IWL_SIXTY_SECS          (60000)
+
 enum iwl_reset {
        IWL_RF_RESET = 0,
        IWL_FW_RESET,
@@ -1354,6 +1363,7 @@ struct iwl_priv {
        struct work_struct run_time_calib_work;
        struct timer_list statistics_periodic;
        struct timer_list ucode_trace;
+       struct timer_list monitor_recover;
        bool hw_ready;
 
        struct iwl_event_log event_log;

diff --git a/drivers/net/wireless/iwlwifi/iwl-tx.c b/drivers/net/wireless/iwlwifi/iwl-tx.c
index 045e4a67344b8bbad42d575e9bb8588c8d39a52e..34c983833a8f94a11249037ee0748347aa6bdf0f 100644 (file)
--- a/drivers/net/wireless/iwlwifi/iwl-tx.c
+++ b/drivers/net/wireless/iwlwifi/iwl-tx.c
@@ -322,6 +322,8 @@ static int iwl_queue_init(struct iwl_priv *priv, struct iwl_queue *q,
                q->high_mark = 2;
 
        q->write_ptr = q->read_ptr = 0;
+       q->last_read_ptr = 0;
+       q->repeat_same_read_ptr = 0;
 
        return 0;
 }

diff --git a/drivers/net/wireless/iwlwifi/iwl3945-base.c b/drivers/net/wireless/iwlwifi/iwl3945-base.c
index 6687b94565543e498e9fe77efbafc73abafa6acc..4995134d7e4a1f56372bdd81747e808d3b7202dd 100644 (file)
--- a/drivers/net/wireless/iwlwifi/iwl3945-base.c
+++ b/drivers/net/wireless/iwlwifi/iwl3945-base.c
@@ -2501,6 +2501,13 @@ static void iwl3945_alive_start(struct iwl_priv *priv)
        /* After the ALIVE response, we can send commands to 3945 uCode */
        set_bit(STATUS_ALIVE, &priv->status);
 
+       if (priv->cfg->ops->lib->recover_from_tx_stall) {
+               /* Enable timer to monitor the driver queues */
+               mod_timer(&priv->monitor_recover,
+                       jiffies +
+                       msecs_to_jiffies(priv->cfg->monitor_recover_period));
+       }
+
        if (iwl_is_rfkill(priv))
                return;
 
@@ -3796,6 +3803,13 @@ static void iwl3945_setup_deferred_work(struct iwl_priv *priv)
 
        iwl3945_hw_setup_deferred_work(priv);
 
+       if (priv->cfg->ops->lib->recover_from_tx_stall) {
+               init_timer(&priv->monitor_recover);
+               priv->monitor_recover.data = (unsigned long)priv;
+               priv->monitor_recover.function =
+                       priv->cfg->ops->lib->recover_from_tx_stall;
+       }
+
        tasklet_init(&priv->irq_tasklet, (void (*)(unsigned long))
                     iwl3945_irq_tasklet, (unsigned long)priv);
 }
@@ -3808,6 +3822,8 @@ static void iwl3945_cancel_deferred_work(struct iwl_priv *priv)
        cancel_delayed_work(&priv->scan_check);
        cancel_delayed_work(&priv->alive_start);
        cancel_work_sync(&priv->beacon_update);
+       if (priv->cfg->ops->lib->recover_from_tx_stall)
+               del_timer_sync(&priv->monitor_recover);
 }
 
 static struct attribute *iwl3945_sysfs_entries[] = {