iwlwifi: mvm: beacon statistics shouldn't go backwards

commit 290d5e49 upstream.

We reset statistics also in case that we didn't reassoc so in
this cases keep last beacon counter.

Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Mordechay Goodstein <mordechay.goodstein@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/iwlwifi.20200417100405.1f9142751fbc.Ifbfd0f928a0a761110b8f4f2ca5483a61fb21131@changeidSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

@@ -587,6 +587,7 @@ void iwl_mvm_rx_rx_mpdu(struct iwl_mvm *mvm, struct napi_struct *napi,
 
 struct iwl_mvm_stat_data {
 	struct iwl_mvm *mvm;
+	__le32 flags;
 	__le32 mac_id;
 	u8 beacon_filter_average_energy;
 	void *general;
@@ -630,6 +631,13 @@ static void iwl_mvm_stat_iterator(void *_data, u8 *mac,
 		}
 	}
 
+	/* make sure that beacon statistics don't go backwards with TCM
+	 * request to clear statistics
+	 */
+	if (le32_to_cpu(data->flags) & IWL_STATISTICS_REPLY_FLG_CLEAR)
+		mvmvif->beacon_stats.accu_num_beacons +=
+			mvmvif->beacon_stats.num_beacons;
+
 	if (mvmvif->id != id)
 		return;
 
@@ -790,6 +798,7 @@ void iwl_mvm_handle_rx_statistics(struct iwl_mvm *mvm,
 
 		flags = stats->flag;
 	}
+	data.flags = flags;
 
 	iwl_mvm_rx_stats_check_trigger(mvm, pkt);