ath10k: fix beacon deadlock

This should fix a very rare occurrence of the following deadlock:

  [<ffffffffa018265e>] ath10k_wmi_tx_beacons_nowait+0x1e/0x50 [ath10k_core]
  [<ffffffffa01829b6>] ath10k_wmi_op_ep_tx_credits+0x16/0x40 [ath10k_core]
  [<ffffffffa017d685>] ath10k_htc_send+0x285/0x3d0 [ath10k_core]
  [<ffffffffa0184b81>] ath10k_wmi_cmd_send_nowait+0x81/0x110 [ath10k_core]
  [<ffffffffa0184c61>] ath10k_wmi_tx_beacon_nowait.part.33+0x51/0x90 [ath10k_core]
  [<ffffffffa0184cd0>] ath10k_wmi_tx_beacons_iter+0x30/0x40 [ath10k_core]
  [<ffffffff81882246>] __iterate_active_interfaces+0xa6/0x100
  [<ffffffffa0184ca0>] ? ath10k_wmi_tx_beacon_nowait.part.33+0x90/0x90 [ath10k_core]
  [<ffffffff818822ae>] ieee80211_iterate_active_interfaces_atomic+0xe/0x10
  [<ffffffffa0182676>] ath10k_wmi_tx_beacons_nowait+0x36/0x50 [ath10k_core]
  [<ffffffffa01829b6>] ath10k_wmi_op_ep_tx_credits+0x16/0x40 [ath10k_core]
  [<ffffffffa017d140>] ath10k_htc_rx+0x280/0x410 [ath10k_core]
  [<ffffffffa01bcbf0>] ? ath10k_ce_completed_recv_next+0x60/0x80 [ath10k_pci]
  [<ffffffffa01bc6ab>] ath10k_pci_ce_recv_data+0x11b/0x1d0 [ath10k_pci]
  [<ffffffffa01bcf44>] ath10k_ce_per_engine_service+0x64/0xc0 [ath10k_pci]
  [<ffffffffa01bcfc2>] ath10k_ce_per_engine_service_any+0x22/0x50 [ath10k_pci]
  [<ffffffffa01bc4d0>] ath10k_pci_tasklet+0x30/0x90 [ath10k_pci]
  [<ffffffff81055a55>] tasklet_action+0xc5/0x100

To prevent this make sure to release ar->data_lock
while calling to ath10k_wmi_beacon_send_ref_nowait().

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

diff --git a/drivers/net/wireless/ath/ath10k/core.h b/drivers/net/wireless/ath/ath10k/core.h
index a47b41d..c8ba6bd 100644 (file)
--- a/drivers/net/wireless/ath/ath10k/core.h
+++ b/drivers/net/wireless/ath/ath10k/core.h
@@ -262,6 +262,12 @@ struct ath10k_sta {
 
 #define ATH10K_VDEV_SETUP_TIMEOUT_HZ (5*HZ)
 
+enum ath10k_beacon_state {
+       ATH10K_BEACON_SCHEDULED = 0,
+       ATH10K_BEACON_SENDING,
+       ATH10K_BEACON_SENT,
+};
+
 struct ath10k_vif {
        struct list_head list;
 
@@ -272,7 +278,7 @@ struct ath10k_vif {
        u32 dtim_period;
        struct sk_buff *beacon;
        /* protected by data_lock */
-       bool beacon_sent;
+       enum ath10k_beacon_state beacon_state;
        void *beacon_buf;
        dma_addr_t beacon_paddr;
 

diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c
index d3fe1a3..d0d882d 100644 (file)
--- a/drivers/net/wireless/ath/ath10k/mac.c
+++ b/drivers/net/wireless/ath/ath10k/mac.c
@@ -531,10 +531,14 @@ void ath10k_mac_vif_beacon_free(struct ath10k_vif *arvif)
                dma_unmap_single(ar->dev, ATH10K_SKB_CB(arvif->beacon)->paddr,
                                 arvif->beacon->len, DMA_TO_DEVICE);
 
+       if (WARN_ON(arvif->beacon_state != ATH10K_BEACON_SCHEDULED &&
+                   arvif->beacon_state != ATH10K_BEACON_SENT))
+               return;
+
        dev_kfree_skb_any(arvif->beacon);
 
        arvif->beacon = NULL;
-       arvif->beacon_sent = false;
+       arvif->beacon_state = ATH10K_BEACON_SCHEDULED;
 }
 
 static void ath10k_mac_vif_beacon_cleanup(struct ath10k_vif *arvif)

diff --git a/drivers/net/wireless/ath/ath10k/wmi.c b/drivers/net/wireless/ath/ath10k/wmi.c
index 01c0230..d6c5b42 100644 (file)
--- a/drivers/net/wireless/ath/ath10k/wmi.c
+++ b/drivers/net/wireless/ath/ath10k/wmi.c
@@ -956,30 +956,45 @@ err_pull:
 
 static void ath10k_wmi_tx_beacon_nowait(struct ath10k_vif *arvif)
 {
-       struct sk_buff *bcn;
+       struct ath10k *ar = arvif->ar;
        struct ath10k_skb_cb *cb;
+       struct sk_buff *bcn;
        int ret;
 
-       lockdep_assert_held(&arvif->ar->data_lock);
+       spin_lock_bh(&ar->data_lock);
 
-       if (arvif->beacon == NULL)
-               return;
+       bcn = arvif->beacon;
 
-       if (arvif->beacon_sent)
-               return;
+       if (!bcn)
+               goto unlock;
 
-       bcn = arvif->beacon;
        cb = ATH10K_SKB_CB(bcn);
-       ret = ath10k_wmi_beacon_send_ref_nowait(arvif->ar, arvif->vdev_id,
-                                               bcn->data, bcn->len, cb->paddr,
-                                               cb->bcn.dtim_zero,
-                                               cb->bcn.deliver_cab);
-       if (ret)
-               return;
 
-       /* We need to retain the arvif->beacon reference for DMA unmapping and
-        * freeing the skbuff later. */
-       arvif->beacon_sent = true;
+       switch (arvif->beacon_state) {
+       case ATH10K_BEACON_SENDING:
+       case ATH10K_BEACON_SENT:
+               break;
+       case ATH10K_BEACON_SCHEDULED:
+               arvif->beacon_state = ATH10K_BEACON_SENDING;
+               spin_unlock_bh(&ar->data_lock);
+
+               ret = ath10k_wmi_beacon_send_ref_nowait(arvif->ar,
+                                                       arvif->vdev_id,
+                                                       bcn->data, bcn->len,
+                                                       cb->paddr,
+                                                       cb->bcn.dtim_zero,
+                                                       cb->bcn.deliver_cab);
+
+               spin_lock_bh(&ar->data_lock);
+
+               if (ret == 0)
+                       arvif->beacon_state = ATH10K_BEACON_SENT;
+               else
+                       arvif->beacon_state = ATH10K_BEACON_SCHEDULED;
+       }
+
+unlock:
+       spin_unlock_bh(&ar->data_lock);
 }
 
 static void ath10k_wmi_tx_beacons_iter(void *data, u8 *mac,
@@ -992,12 +1007,10 @@ static void ath10k_wmi_tx_beacons_iter(void *data, u8 *mac,
 
 static void ath10k_wmi_tx_beacons_nowait(struct ath10k *ar)
 {
-       spin_lock_bh(&ar->data_lock);
        ieee80211_iterate_active_interfaces_atomic(ar->hw,
                                                   IEEE80211_IFACE_ITER_NORMAL,
                                                   ath10k_wmi_tx_beacons_iter,
                                                   NULL);
-       spin_unlock_bh(&ar->data_lock);
 }
 
 static void ath10k_wmi_op_ep_tx_credits(struct ath10k *ar)
@@ -2459,9 +2472,19 @@ void ath10k_wmi_event_host_swba(struct ath10k *ar, struct sk_buff *skb)
                spin_lock_bh(&ar->data_lock);
 
                if (arvif->beacon) {
-                       if (!arvif->beacon_sent)
-                               ath10k_warn(ar, "SWBA overrun on vdev %d\n",
+                       switch (arvif->beacon_state) {
+                       case ATH10K_BEACON_SENT:
+                               break;
+                       case ATH10K_BEACON_SCHEDULED:
+                               ath10k_warn(ar, "SWBA overrun on vdev %d, skipped old beacon\n",
+                                           arvif->vdev_id);
+                               break;
+                       case ATH10K_BEACON_SENDING:
+                               ath10k_warn(ar, "SWBA overrun on vdev %d, skipped new beacon\n",
                                            arvif->vdev_id);
+                               dev_kfree_skb(bcn);
+                               goto skip;
+                       }
 
                        ath10k_mac_vif_beacon_free(arvif);
                }
@@ -2489,15 +2512,16 @@ void ath10k_wmi_event_host_swba(struct ath10k *ar, struct sk_buff *skb)
                }
 
                arvif->beacon = bcn;
-               arvif->beacon_sent = false;
+               arvif->beacon_state = ATH10K_BEACON_SCHEDULED;
 
                trace_ath10k_tx_hdr(ar, bcn->data, bcn->len);
                trace_ath10k_tx_payload(ar, bcn->data, bcn->len);
 
-               ath10k_wmi_tx_beacon_nowait(arvif);
 skip:
                spin_unlock_bh(&ar->data_lock);
        }
+
+       ath10k_wmi_tx_beacons_nowait(ar);
 }
 
 void ath10k_wmi_event_tbttoffset_update(struct ath10k *ar, struct sk_buff *skb)