diff --git a/[refs] b/[refs]
index faad539f15eb..dfa1aa08beb5 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 902762831c0068ba0c8c8fca801e505a9881aa01
+refs/heads/master: 21db1882f79a1ad5977cae6766376a63f60ec414
diff --git a/trunk/drivers/scsi/Kconfig b/trunk/drivers/scsi/Kconfig
index 5881464a938d..8442be1bb162 100644
--- a/trunk/drivers/scsi/Kconfig
+++ b/trunk/drivers/scsi/Kconfig
@@ -216,6 +216,23 @@ config SCSI_LOGGING
 	  there should be no noticeable performance impact as long as you have
 	  logging turned off.
 
+config SCSI_SCAN_ASYNC
+	bool "Asynchronous SCSI scanning"
+	depends on SCSI
+	help
+	  The SCSI subsystem can probe for devices while the rest of the
+	  system continues booting, and even probe devices on different
+	  busses in parallel, leading to a significant speed-up.
+	  If you have built SCSI as modules, enabling this option can
+	  be a problem as the devices may not have been found by the
+	  time your system expects them to have been.  You can load the
+	  scsi_wait_scan module to ensure that all scans have completed.
+	  If you build your SCSI drivers into the kernel, then everything
+	  will work fine if you say Y here.
+
+	  You can override this choice by specifying scsi_mod.scan="sync"
+	  or "async" on the kernel's command line.
+
 menu "SCSI Transports"
 	depends on SCSI
 
diff --git a/trunk/drivers/scsi/scsi_scan.c b/trunk/drivers/scsi/scsi_scan.c
index aa1b1e0e9d22..d91d268dd331 100644
--- a/trunk/drivers/scsi/scsi_scan.c
+++ b/trunk/drivers/scsi/scsi_scan.c
@@ -89,7 +89,13 @@ module_param_named(max_luns, max_scsi_luns, int, S_IRUGO|S_IWUSR);
 MODULE_PARM_DESC(max_luns,
 		 "last scsi LUN (should be between 1 and 2^32-1)");
 
-static char scsi_scan_type[6] = "sync";
+#ifdef CONFIG_SCSI_SCAN_ASYNC
+#define SCSI_SCAN_TYPE_DEFAULT "async"
+#else
+#define SCSI_SCAN_TYPE_DEFAULT "sync"
+#endif
+
+static char scsi_scan_type[6] = SCSI_SCAN_TYPE_DEFAULT;
 
 module_param_string(scan, scsi_scan_type, sizeof(scsi_scan_type), S_IRUGO);
 MODULE_PARM_DESC(scan, "sync, async or none");