iwlwifi: pcie: WARN upon traffic while flushing TX queues

This must not happen - otherwise we might keep flushing
forever.

Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

diff --git a/drivers/net/wireless/iwlwifi/pcie/trans.c b/drivers/net/wireless/iwlwifi/pcie/trans.c
index 0f20e73b2596601bb57e68e818c0c9b207a8e705..4845d5019c4be8751f8a13ad31bf07210956e92a 100644 (file)
--- a/drivers/net/wireless/iwlwifi/pcie/trans.c
+++ b/drivers/net/wireless/iwlwifi/pcie/trans.c
@@ -1270,6 +1270,8 @@ static int iwl_trans_pcie_wait_txq_empty(struct iwl_trans *trans, u32 txq_bm)
 
        /* waiting for all the tx frames complete might take a while */
        for (cnt = 0; cnt < trans->cfg->base_params->num_of_queues; cnt++) {
+               u8 wr_ptr;
+
                if (cnt == trans_pcie->cmd_queue)
                        continue;
                if (!test_bit(cnt, trans_pcie->queue_used))
@@ -1278,9 +1280,19 @@ static int iwl_trans_pcie_wait_txq_empty(struct iwl_trans *trans, u32 txq_bm)
                        continue;
                txq = &trans_pcie->txq[cnt];
                q = &txq->q;
-               while (q->read_ptr != q->write_ptr && !time_after(jiffies,
-                      now + msecs_to_jiffies(IWL_FLUSH_WAIT_MS)))
+               wr_ptr = ACCESS_ONCE(q->write_ptr);
+
+               while (q->read_ptr != ACCESS_ONCE(q->write_ptr) &&
+                      !time_after(jiffies,
+                                  now + msecs_to_jiffies(IWL_FLUSH_WAIT_MS))) {
+                       u8 write_ptr = ACCESS_ONCE(q->write_ptr);
+
+                       if (WARN_ONCE(wr_ptr != write_ptr,
+                                     "WR pointer moved while flushing %d -> %d\n",
+                                     wr_ptr, write_ptr))
+                               return -ETIMEDOUT;
                        msleep(1);
+               }
 
                if (q->read_ptr != q->write_ptr) {
                        IWL_ERR(trans,