Hello Johannes Berg,
This is a semi-automatic email about new static checker warnings.
The patch 3a8aea098c8e: "iwlagn: use 6 Mbps rate for no-CCK scans"
from Oct 14, 2011, leads to the following Smatch complaint:
drivers/net/wireless/iwlwifi/iwl-scan.c +782 iwlagn_request_scan()
error: we previously assumed 'priv->scan_request' could be null (see line 681)
drivers/net/wireless/iwlwifi/iwl-scan.c
680 >> RXON_FLG_CHANNEL_MODE_POS;
681 if ((priv->scan_request && priv->scan_request->no_cck) ||
^^^^^^^^^^^^^^^^^^
newly introduced check. (Probably not needed. Nothing else in this
function checks this).
682 chan_mod == CHANNEL_MODE_PURE_40) {
683 rate = IWL_RATE_6M_PLCP;
684 } else {
685 rate = IWL_RATE_1M_PLCP;
686 rate_flags = RATE_MCS_CCK_MSK;
687 }
688 /*
689 * Internal scans are passive, so we can indiscriminately set
690 * the BT ignore flag on 2.4 GHz since it applies to TX only.
691 */
692 if (priv->cfg->bt_params &&
693 priv->cfg->bt_params->advanced_bt_coexist)
694 scan->tx_cmd.tx_flags |= TX_CMD_FLG_IGNORE_BT;
695 break;
696 case IEEE80211_BAND_5GHZ:
697 rate = IWL_RATE_6M_PLCP;
698 break;
699 default:
700 IWL_WARN(priv, "Invalid scan band\n");
701 return -EIO;
702 }
703
704 /*
705 * If active scanning is requested but a certain channel is
706 * marked passive, we can do active scanning if we detect
707 * transmissions.
708 *
709 * There is an issue with some firmware versions that triggers
710 * a sysassert on a "good CRC threshold" of zero (== disabled),
711 * on a radar channel even though this means that we should NOT
712 * send probes.
713 *
714 * The "good CRC threshold" is the number of frames that we
715 * need to receive during our dwell time on a channel before
716 * sending out probes -- setting this to a huge value will
717 * mean we never reach it, but at the same time work around
718 * the aforementioned issue. Thus use IWL_GOOD_CRC_TH_NEVER
719 * here instead of IWL_GOOD_CRC_TH_DISABLED.
720 *
721 * This was fixed in later versions along with some other
722 * scan changes, and the threshold behaves as a flag in those
723 * versions.
724 */
725 if (priv->new_scan_threshold_behaviour)
726 scan->good_CRC_th = is_active ? IWL_GOOD_CRC_TH_DEFAULT :
727 IWL_GOOD_CRC_TH_DISABLED;
728 else
729 scan->good_CRC_th = is_active ? IWL_GOOD_CRC_TH_DEFAULT :
730 IWL_GOOD_CRC_TH_NEVER;
731
732 band = priv->scan_band;
733
734 if (priv->cfg->scan_rx_antennas[band])
735 rx_ant = priv->cfg->scan_rx_antennas[band];
736
737 if (band == IEEE80211_BAND_2GHZ &&
738 priv->cfg->bt_params &&
739 priv->cfg->bt_params->advanced_bt_coexist) {
740 /* transmit 2.4 GHz probes only on first antenna */
741 scan_tx_antennas = first_antenna(scan_tx_antennas);
742 }
743
744 priv->scan_tx_ant[band] = iwl_toggle_tx_ant(priv,
745 priv->scan_tx_ant[band],
746 scan_tx_antennas);
747 rate_flags |= iwl_ant_idx_to_flags(priv->scan_tx_ant[band]);
748 scan->tx_cmd.rate_n_flags = iwl_hw_set_rate_n_flags(rate, rate_flags);
749
750 /* In power save mode use one chain, otherwise use all chains */
751 if (test_bit(STATUS_POWER_PMI, &priv->shrd->status)) {
752 /* rx_ant has been set to all valid chains previously */
753 active_chains = rx_ant &
754 ((u8)(priv->chain_noise_data.active_chains));
755 if (!active_chains)
756 active_chains = rx_ant;
757
758 IWL_DEBUG_SCAN(priv, "chain_noise_data.active_chains: %u\n",
759 priv->chain_noise_data.active_chains);
760
761 rx_ant = first_antenna(active_chains);
762 }
763 if (priv->cfg->bt_params &&
764 priv->cfg->bt_params->advanced_bt_coexist &&
765 priv->bt_full_concurrent) {
766 /* operated as 1x1 in full concurrency mode */
767 rx_ant = first_antenna(rx_ant);
768 }
769
770 /* MIMO is not used here, but value is required */
771 rx_chain |=
772 hw_params(priv).valid_rx_ant << RXON_RX_CHAIN_VALID_POS;
773 rx_chain |= rx_ant << RXON_RX_CHAIN_FORCE_MIMO_SEL_POS;
774 rx_chain |= rx_ant << RXON_RX_CHAIN_FORCE_SEL_POS;
775 rx_chain |= 0x1 << RXON_RX_CHAIN_DRIVER_FORCE_POS;
776 scan->rx_chain = cpu_to_le16(rx_chain);
777 switch (priv->scan_type) {
778 case IWL_SCAN_NORMAL:
779 cmd_len = iwl_fill_probe_req(priv,
780 (struct ieee80211_mgmt *)scan->data,
781 vif->addr,
782 priv->scan_request->ie,
^^^^^^^^^^^^^^^^^^^^
unchecked dereference.
783 priv->scan_request->ie_len,
784 IWL_MAX_SCAN_SIZE - sizeof(*scan));
regards,
dan carpenter
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