qcacld-3.0: Synchronize __con_mode_handler and __hdd_open

Interface up runs in normal mode (wifi@1.0-service) and it gets
preempted by the con_mode change handler when Monitor mode is
invoked via user. Then again when the normal mode gets scheduled
after the completion of Monitor mode, it tries to access contents
freed during the con_mode change.

The execution of __con_mode_handler and __hdd_open is
synchronized with help of a mutex lock and an atomic variable

Change-Id: Ia78c225a21e2c505ffae6b16647ba8f2c661bbbd
CRs-Fixed: 2158683

core/hdd/inc/wlan_hdd_main.h

@@ -1547,6 +1547,7 @@ struct hdd_context {
 	/* defining the solution type */
 	uint32_t target_type;
 
+	qdf_atomic_t con_mode_flag;
 	/* defining the firmware version */
 	uint32_t target_fw_version;
 	uint32_t target_fw_vers_ext;

core/hdd/src/wlan_hdd_main.c

@@ -2804,8 +2804,12 @@ static int __hdd_open(struct net_device *dev)
 		return -EBUSY;
 	}
 
-	mutex_lock(&hdd_init_deinit_lock);
+	if (qdf_atomic_read(&hdd_ctx->con_mode_flag)) {
+		hdd_err("con_mode_handler is in progress; Please try again.");
+		return -EBUSY;
+	}
 
+	mutex_lock(&hdd_init_deinit_lock);
 	hdd_start_driver_ops_timer(eHDD_DRV_OP_IFF_UP);
 
 	/*
@@ -10371,6 +10375,7 @@ int hdd_wlan_startup(struct device *dev)
 #endif
 
 	hdd_request_manager_init();
+	qdf_atomic_init(&hdd_ctx->con_mode_flag);
 
 	hdd_driver_memdump_init();
 
@@ -12158,6 +12163,7 @@ static int __con_mode_handler(const char *kmessage, struct kernel_param *kp,
 	if (ret)
 		return ret;
 
+	qdf_atomic_set(&hdd_ctx->con_mode_flag, 1);
 	cds_set_load_in_progress(true);
 
 	ret = kstrtoint(kmessage, 0, &new_con_mode);
@@ -12165,6 +12171,7 @@ static int __con_mode_handler(const char *kmessage, struct kernel_param *kp,
 		hdd_err("Failed to parse con_mode '%s'", kmessage);
 		goto reset_flags;
 	}
+	mutex_lock(&hdd_init_deinit_lock);
 
 	if (!is_con_mode_valid(new_con_mode)) {
 		hdd_err("invalid con_mode %d", new_con_mode);
@@ -12180,9 +12187,6 @@ static int __con_mode_handler(const char *kmessage, struct kernel_param *kp,
 		goto reset_flags;
 	}
 
-	if (!cds_wait_for_external_threads_completion(__func__))
-		hdd_warn("Waiting for monitor mode: External threads are active");
-
 	/* ensure adapters are stopped */
 	hdd_stop_present_mode(hdd_ctx, curr_mode);
 
@@ -12247,8 +12251,9 @@ static int __con_mode_handler(const char *kmessage, struct kernel_param *kp,
 	ret = 0;
 
 reset_flags:
+	mutex_unlock(&hdd_init_deinit_lock);
 	cds_set_load_in_progress(false);
-
+	qdf_atomic_set(&hdd_ctx->con_mode_flag, 0);
 	return ret;
 }