iwlwifi: pcie: free RBs during configure

When switching op-modes, or more generally when reconfiguring,
we might switch the RB size. In _iwl_pcie_rx_init() we have a
comment saying we must free all RBs since we might switch the
size, but this is actually too late: the switch has been done
and we'll free the buffers with the wrong size.

Fix this by always freeing the buffers, if any, at the start
of configure, instead of only after the size may have changed.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210802170640.42d7c93279c4.I07f74e65aab0e3d965a81206fcb289dc92d74878@changeidSigned-off-by: Luca Coelho <luciano.coelho@intel.com>

drivers/net/wireless/intel/iwlwifi/pcie/rx.c

@@ -487,6 +487,9 @@ void iwl_pcie_free_rbs_pool(struct iwl_trans *trans)
 	struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
 	int i;
 
+	if (!trans_pcie->rx_pool)
+		return;
+
 	for (i = 0; i < RX_POOL_SIZE(trans_pcie->num_rx_bufs); i++) {
 		if (!trans_pcie->rx_pool[i].page)
 			continue;
@@ -1062,7 +1065,7 @@ static int _iwl_pcie_rx_init(struct iwl_trans *trans)
 	INIT_LIST_HEAD(&rba->rbd_empty);
 	spin_unlock_bh(&rba->lock);
 
-	/* free all first - we might be reconfigured for a different size */
+	/* free all first - we overwrite everything here */
 	iwl_pcie_free_rbs_pool(trans);
 
 	for (i = 0; i < RX_QUEUE_SIZE; i++)

drivers/net/wireless/intel/iwlwifi/pcie/trans.c

@@ -1866,6 +1866,9 @@ static void iwl_trans_pcie_configure(struct iwl_trans *trans,
 {
 	struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
 
+	/* free all first - we might be reconfigured for a different size */
+	iwl_pcie_free_rbs_pool(trans);
+
 	trans->txqs.cmd.q_id = trans_cfg->cmd_queue;
 	trans->txqs.cmd.fifo = trans_cfg->cmd_fifo;
 	trans->txqs.cmd.wdg_timeout = trans_cfg->cmd_q_wdg_timeout;