iwlwifi: do not nulify ctx->vif on reset

commit 8db4c7e2 upstream.

ctx->vif is dereferenced in different part of iwlwifi code, so do not
nullify it.

This should address at least one of the possible reasons of WARNING at
iwlagn_mac_remove_interface, and perhaps some random crashes when
firmware reset is performed.
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
[bwh: Backported to 3.2:
 - Change filename iwl-mac80211.c to iwl-core.c
 - Change context in iwlagn_prepare_restart()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/net/wireless/iwlwifi/iwl-agn.c

@@ -1504,7 +1504,6 @@ static void iwl_bg_run_time_calib_work(struct work_struct *work)
 
 static void iwlagn_prepare_restart(struct iwl_priv *priv)
 {
-	struct iwl_rxon_context *ctx;
 	bool bt_full_concurrent;
 	u8 bt_ci_compliance;
 	u8 bt_load;
@@ -1513,8 +1512,6 @@ static void iwlagn_prepare_restart(struct iwl_priv *priv)
 
 	lockdep_assert_held(&priv->shrd->mutex);
 
-	for_each_context(priv, ctx)
-		ctx->vif = NULL;
 	priv->is_open = 0;
 
 	/*

drivers/net/wireless/iwlwifi/iwl-core.c

@@ -1228,6 +1228,7 @@ int iwlagn_mac_add_interface(struct ieee80211_hw *hw,
 	struct iwl_rxon_context *tmp, *ctx = NULL;
 	int err;
 	enum nl80211_iftype viftype = ieee80211_vif_type_p2p(vif);
+	bool reset = false;
 
 	IWL_DEBUG_MAC80211(priv, "enter: type %d, addr %pM\n",
 			   viftype, vif->addr);
@@ -1249,6 +1250,13 @@ int iwlagn_mac_add_interface(struct ieee80211_hw *hw,
 			tmp->interface_modes | tmp->exclusive_interface_modes;
 
 		if (tmp->vif) {
+			/* On reset we need to add the same interface again */
+			if (tmp->vif == vif) {
+				reset = true;
+				ctx = tmp;
+				break;
+			}
+
 			/* check if this busy context is exclusive */
 			if (tmp->exclusive_interface_modes &
 						BIT(tmp->vif->type)) {
@@ -1275,7 +1283,7 @@ int iwlagn_mac_add_interface(struct ieee80211_hw *hw,
 	ctx->vif = vif;
 
 	err = iwl_setup_interface(priv, ctx);
-	if (!err)
+	if (!err || reset)
 		goto out;
 
 	ctx->vif = NULL;