Driver core: add CONFIG_UEVENT_HELPER_PATH

The kernel creates a process for every event that is send, even when
there is no binary it could execute.  We are needlessly creating around
200-300 failing processes during early bootup, until we have the chance
to disable it from userspace.

This change allows us to disable /sbin/hotplug entirely, if you want to,
by setting UEVENT_HELPER_PATH="" in the kernel config.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/base/Kconfig

 menu "Generic Driver Options"
 
+config UEVENT_HELPER_PATH
+	string "path to uevent helper"
+	depends on HOTPLUG
+	default "/sbin/hotplug"
+	help
+	  Path to uevent helper program forked by the kernel for
+	  every uevent.
+
 config STANDALONE
 	bool "Select only drivers that don't need compile-time external firmware" if EXPERIMENTAL
 	default y

lib/kobject_uevent.c

@@ -35,7 +35,7 @@ const char *kobject_actions[] = {
 
 #if defined(CONFIG_HOTPLUG)
 u64 uevent_seqnum;
-char uevent_helper[UEVENT_HELPER_PATH_LEN] = "/sbin/hotplug";
+char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH;
 static DEFINE_SPINLOCK(sequence_lock);
 #if defined(CONFIG_NET)
 static struct sock *uevent_sock;