linux-kernel - [ 43/72] iwlwifi: pcie: fix race in queue unmapping

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Date:	Thu, 18 Jul 2013 22:26:00 -0700
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>,
	Johannes Berg <johannes.berg@...el.com>
Subject: [ 43/72] iwlwifi: pcie: fix race in queue unmapping

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

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

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

commit b967613d7e7c7bad176f5627c55e2d8c5aa2480e upstream.

When a queue is disabled, it frees all its entries. Later,
the op_mode might still get notifications from the firmware
that triggers to free entries in the tx queue. The transport
should be prepared for these races and know to ignore
reclaim calls on queues that have been disabled and whose
entries have been freed.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@...el.com>
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/wireless/iwlwifi/pcie/tx.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

--- a/drivers/net/wireless/iwlwifi/pcie/tx.c
+++ b/drivers/net/wireless/iwlwifi/pcie/tx.c
@@ -576,9 +576,12 @@ static void iwl_pcie_txq_unmap(struct iw
 
 	spin_lock_bh(&txq->lock);
 	while (q->write_ptr != q->read_ptr) {
+		IWL_DEBUG_TX_REPLY(trans, "Q %d Free %d\n",
+				   txq_id, q->read_ptr);
 		iwl_pcie_txq_free_tfd(trans, txq);
 		q->read_ptr = iwl_queue_inc_wrap(q->read_ptr, q->n_bd);
 	}
+	txq->active = false;
 	spin_unlock_bh(&txq->lock);
 }
 
@@ -927,6 +930,12 @@ void iwl_trans_pcie_reclaim(struct iwl_t
 
 	spin_lock_bh(&txq->lock);
 
+	if (!txq->active) {
+		IWL_DEBUG_TX_QUEUES(trans, "Q %d inactive - ignoring idx %d\n",
+				    txq_id, ssn);
+		goto out;
+	}
+
 	if (txq->q.read_ptr == tfd_num)
 		goto out;
 
@@ -1103,6 +1112,7 @@ void iwl_trans_pcie_txq_enable(struct iw
 		       (fifo << SCD_QUEUE_STTS_REG_POS_TXF) |
 		       (1 << SCD_QUEUE_STTS_REG_POS_WSL) |
 		       SCD_QUEUE_STTS_REG_MSK);
+	trans_pcie->txq[txq_id].active = true;
 	IWL_DEBUG_TX_QUEUES(trans, "Activate queue %d on FIFO %d WrPtr: %d\n",
 			    txq_id, fifo, ssn & 0xff);
 }


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