iwlwifi: enable serialization of synchronous commands

Until now it was only possible to have one synchronous command running at
any time. If a synchronous command is in progress when a second request
arrives then the second command will fail. Create a new mutex specific for
this purpose to only allow one synchronous command at a time, but enable
other commands to wait instead of fail if a synchronous command is in
progress.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-tx.c b/drivers/net/wireless/iwlwifi/iwl-tx.c
index d8c11f9..38655ad 100644
--- a/drivers/net/wireless/iwlwifi/iwl-tx.c
+++ b/drivers/net/wireless/iwlwifi/iwl-tx.c
@@ -1238,6 +1238,8 @@
 
 	if (!(meta->flags & CMD_ASYNC)) {
 		clear_bit(STATUS_HCMD_ACTIVE, &priv->status);
+		IWL_DEBUG_INFO(priv, "Clearing HCMD_ACTIVE for command %s \n",
+			       get_cmd_string(cmd->hdr.cmd));
 		wake_up_interruptible(&priv->wait_command_queue);
 	}
 }