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[10/15] wifi: iwlwifi: read txq->read_ptr under lock

Message ID 20240319100755.bf4c62196504.I978a7ca56c6bd6f1bf42c15aa923ba03366a840b@changeid (mailing list archive)
State Accepted
Delegated to: Johannes Berg
Headers show
Series wifi: iwlwifi: updates - 2024-03-19 | expand

Commit Message

Korenblit, Miriam Rachel March 19, 2024, 8:10 a.m. UTC 
From: Johannes Berg <johannes.berg@intel.com>

If we read txq->read_ptr without lock, we can read the same
value twice, then obtain the lock, and reclaim from there
to two different places, but crucially reclaim the same
entry twice, resulting in the WARN_ONCE() a little later.
Fix that by reading txq->read_ptr under lock.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
---
 drivers/net/wireless/intel/iwlwifi/queue/tx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/net/wireless/intel/iwlwifi/queue/tx.c b/drivers/net/wireless/intel/iwlwifi/queue/tx.c
index 33973a60d0bf..6229c785c845 100644
--- a/drivers/net/wireless/intel/iwlwifi/queue/tx.c
+++ b/drivers/net/wireless/intel/iwlwifi/queue/tx.c
@@ -1589,9 +1589,9 @@  void iwl_txq_reclaim(struct iwl_trans *trans, int txq_id, int ssn,
 		return;
 
 	tfd_num = iwl_txq_get_cmd_index(txq, ssn);
-	read_ptr = iwl_txq_get_cmd_index(txq, txq->read_ptr);
 
 	spin_lock_bh(&txq->lock);
+	read_ptr = iwl_txq_get_cmd_index(txq, txq->read_ptr);
 
 	if (!test_bit(txq_id, trans->txqs.queue_used)) {
 		IWL_DEBUG_TX_QUEUES(trans, "Q %d inactive - ignoring idx %d\n",