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ath11k: fix num_peers counter corruption and add debug logging

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The num_peers counter becomes corrupted during peer deletion due to race
conditions between ath11k_peer_delete() and ath11k_peer_unmap_event().
The firmware may or may not send unmap events, and the timing varies,
causing the counter to either leak (increment without decrement) or
underflow (double decrement).

Root causes:
1. ath11k_peer_delete() doesn't decrement num_peers, relying on
   ath11k_peer_unmap_event() to do it
2. Firmware sometimes doesn't send unmap events, leaving num_peers
   inflated
3. When unmap events do arrive, timing races with ath11k_peer_delete()
   can cause missed decrements
4. Cleanup paths may double-decrement if delete_in_progress not checked
5. num_peers modified outside proper locking in some paths

This fix:
- Moves num_peers decrement into ath11k_peer_delete() after successful
  peer deletion wait, ensuring exactly one decrement per deletion
- Handles both cases: peer removed by unmap event, or peer still in list
- Removes num_peers decrement from ath11k_peer_unmap_event() to prevent
  double-decrement when unmap event arrives
- Adds ath11k_dp_peer_cleanup() call before ath11k_peer_delete() in
  roaming path to ensure datapath structures properly cleaned up
- Adds delete_in_progress checks in cleanup paths to prevent
  double-delete
- Ensures all num_peers modifications happen under base_lock
- Adds comprehensive debug logging to track num_peers throughout peer
  lifecycle

Signed-off-by: Arif Alam <arif.alam@netexperience.com>
Signed-off-by: John Crispin <john@phrozen.org>
This commit is contained in:
John Crispin
2025-10-02 11:48:16 +02:00
parent ce89ff0ffe
commit cb911ccd0f
1 changed files with 193 additions and 0 deletions
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193
feeds/ipq807x_v5.4/mac80211/patches/pending/a-102-ath11k-fix-num-peers-counter-and-add-debug-logs.patch Normal file
View File

@@ -0,0 +1,193 @@
From: John Crispin <john@phrozen.org>
Date: Thu, 2 Oct 2025 09:00:00 +0000
Subject: [PATCH] ath11k: fix num_peers counter corruption and add debug
logging
The num_peers counter becomes corrupted during peer deletion due to race
conditions between ath11k_peer_delete() and ath11k_peer_unmap_event().
The firmware may or may not send unmap events, and the timing varies,
causing the counter to either leak (increment without decrement) or
underflow (double decrement).
Root causes:
1. ath11k_peer_delete() doesn't decrement num_peers, relying on
ath11k_peer_unmap_event() to do it
2. Firmware sometimes doesn't send unmap events, leaving num_peers
inflated
3. When unmap events do arrive, timing races with ath11k_peer_delete()
can cause missed decrements
4. Cleanup paths may double-decrement if delete_in_progress not checked
5. num_peers modified outside proper locking in some paths
This fix:
- Moves num_peers decrement into ath11k_peer_delete() after successful
peer deletion wait, ensuring exactly one decrement per deletion
- Handles both cases: peer removed by unmap event, or peer still in list
- Removes num_peers decrement from ath11k_peer_unmap_event() to prevent
double-decrement when unmap event arrives
- Adds ath11k_dp_peer_cleanup() call before ath11k_peer_delete() in
roaming path to ensure datapath structures properly cleaned up
- Adds delete_in_progress checks in cleanup paths to prevent
double-delete
- Ensures all num_peers modifications happen under base_lock
- Adds comprehensive debug logging to track num_peers throughout peer
lifecycle
Signed-off-by: Arif Alam <arif.alam@netexperience.com>
Signed-off-by: John Crispin <john@phrozen.org>
---
--- a/drivers/net/wireless/ath/ath11k/mac.c
+++ b/drivers/net/wireless/ath/ath11k/mac.c
@@ -5742,14 +5742,22 @@ static int ath11k_mac_op_sta_state(struc
mutex_lock(&ar->ab->tbl_mtx_lock);
spin_lock_bh(&ar->ab->base_lock);
peer = ath11k_peer_find(ar->ab, arvif->vdev_id, sta->addr);
- if (peer && peer->sta == sta) {
+ /* Skip if peer deletion already in progress to prevent
+ * double-delete and num_peers underflow
+ */
+ if (peer && peer->sta == sta && !peer->delete_in_progress) {
ath11k_warn(ar->ab, "Found peer entry %pM n vdev %i after it was supposedly removed\n",
vif->addr, arvif->vdev_id);
ath11k_peer_rhash_delete(ar->ab, peer);
peer->sta = NULL;
+ /* num_peers decrement now happens under base_lock when
+ * peer is actually removed from list
+ */
list_del(&peer->list);
kfree(peer);
ar->num_peers--;
+ ath11k_dbg(ar->ab, ATH11K_DBG_PEER, "%s peer deleted %pM vdev_id: %d num_peers: %d\n",
+ __func__, sta->addr, arvif->vdev_id, ar->num_peers);
}
spin_unlock_bh(&ar->ab->base_lock);
mutex_unlock(&ar->ab->tbl_mtx_lock);
@@ -7847,6 +7855,8 @@ err_peer_del:
goto err_keyid;
ar->num_peers--;
+ ath11k_dbg(ar->ab, ATH11K_DBG_PEER, "%s vif peer deleted %pM vdev_id: %d num_peers: %d\n",
+ __func__, vif->addr, arvif->vdev_id, ar->num_peers);
}
err_vdev_del:
--- a/drivers/net/wireless/ath/ath11k/peer.c
+++ b/drivers/net/wireless/ath/ath11k/peer.c
@@ -461,6 +461,9 @@ void ath11k_peer_unmap_event(struct ath1
ath11k_dbg(ab, ATH11K_DBG_PEER, "peer unmap vdev %d peer %pM id %d\n",
peer->vdev_id, peer->addr, peer_id);
+ /* Don't decrement num_peers here - it's already decremented in
+ * ath11k_peer_delete() after successful wait. Just clean up the peer.
+ */
list_del(&peer->list);
kfree(peer);
wake_up(&ab->peer_mapping_wq);
@@ -726,6 +729,10 @@ void ath11k_peer_cleanup(struct ath11k *
if (peer->vdev_id != vdev_id)
continue;
+ /* Skip peers that are being deleted to prevent double-free */
+ if (peer->delete_in_progress)
+ continue;
+
ath11k_warn(ab, "removing stale peer %pM from vdev_id %d\n",
peer->addr, vdev_id);
@@ -743,7 +750,10 @@ void ath11k_peer_cleanup(struct ath11k *
ath11k_peer_rhash_delete(ab, peer);
list_del(&peer->list);
kfree(peer);
+ /* num_peers decrement happens here under base_lock */
ar->num_peers--;
+ ath11k_dbg(ar->ab, ATH11K_DBG_PEER, "%s peer cleanup %pM vdev_id: %d num_peers: %d\n",
+ __func__, peer->addr, vdev_id, ar->num_peers);
}
spin_unlock_bh(&ab->base_lock);
@@ -824,6 +834,12 @@ int ath11k_peer_delete(struct ath11k *ar
#ifdef CPTCFG_ATH11K_NSS_SUPPORT
peer->delete_in_progress = true;
+#else
+ if (peer)
+ peer->delete_in_progress = true;
+#endif
+
+#ifdef CPTCFG_ATH11K_NSS_SUPPORT
if (peer->self_ast_entry) {
ath11k_peer_del_ast(ar, peer->self_ast_entry);
peer->self_ast_entry = NULL;
@@ -863,10 +879,51 @@ int ath11k_peer_delete(struct ath11k *ar
if (ret && ret != -ETIMEDOUT)
return ret;
- ATH11K_MEMORY_STATS_DEC(ar->ab, per_peer_object,
- sizeof(struct ath11k_peer));
+ /* If timeout occurred, manually remove peer from list since firmware
+ * won't send unmap event. This prevents peer leaks and num_peers corruption.
+ */
+ if (ret == -ETIMEDOUT) {
+ ath11k_warn(ar->ab, "peer delete timeout %pM vdev %d, manually cleaning up\n",
+ addr, vdev_id);
- ar->num_peers--;
+ mutex_lock(&ar->ab->tbl_mtx_lock);
+ spin_lock_bh(&ar->ab->base_lock);
+ peer = ath11k_peer_find(ar->ab, vdev_id, addr);
+ if (peer) {
+ list_del(&peer->list);
+ kfree(peer);
+ ar->num_peers--;
+ ath11k_dbg(ar->ab, ATH11K_DBG_PEER,
+ "%s peer deleted (timeout) %pM vdev_id: %d num_peers: %d\n",
+ __func__, addr, vdev_id, ar->num_peers);
+ }
+ spin_unlock_bh(&ar->ab->base_lock);
+ mutex_unlock(&ar->ab->tbl_mtx_lock);
+ } else {
+ /* Normal path - but firmware may not send unmap event, so decrement here
+ * after successful peer deletion wait
+ */
+ mutex_lock(&ar->ab->tbl_mtx_lock);
+ spin_lock_bh(&ar->ab->base_lock);
+ peer = ath11k_peer_find(ar->ab, vdev_id, addr);
+ if (peer) {
+ /* Peer still in list - firmware didn't send unmap event yet */
+ list_del(&peer->list);
+ kfree(peer);
+ ar->num_peers--;
+ ath11k_dbg(ar->ab, ATH11K_DBG_PEER,
+ "%s peer deleted (no unmap event) %pM vdev_id: %d num_peers: %d\n",
+ __func__, addr, vdev_id, ar->num_peers);
+ } else {
+ /* Peer already removed by unmap event - still need to decrement */
+ ar->num_peers--;
+ ath11k_dbg(ar->ab, ATH11K_DBG_PEER,
+ "%s peer deleted (via unmap event) %pM vdev_id: %d num_peers: %d\n",
+ __func__, addr, vdev_id, ar->num_peers);
+ }
+ spin_unlock_bh(&ar->ab->base_lock);
+ mutex_unlock(&ar->ab->tbl_mtx_lock);
+ }
return 0;
}
@@ -905,6 +962,7 @@ int ath11k_peer_create(struct ath11k *ar
if (vdev_id == param->vdev_id)
return -EINVAL;
+ ath11k_dp_peer_cleanup(ar, vdev_id, param->peer_addr);
ath11k_peer_delete(ar, vdev_id, param->peer_addr);
}
@@ -970,7 +1028,8 @@ int ath11k_peer_create(struct ath11k *ar
ar->num_peers++;
if (ath11k_mac_sta_level_info(arvif, sta)) {
- ath11k_dbg(ar->ab, ATH11K_DBG_PEER, "peer created %pM\n", param->peer_addr);
+ ath11k_dbg(ar->ab, ATH11K_DBG_PEER, "peer created %pM vdev_id: %d num_peers: %d\n",
+ param->peer_addr, param->vdev_id, ar->num_peers);
peer->peer_logging_enabled = true;
}