usermodehelper: Tidy up waiting

Rather than using a tri-state integer for the wait flag in
call_usermodehelper_exec, define a proper enum, and use that.  I've
preserved the integer values so that any callers I've missed should
still work OK.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Andi Kleen <ak@suse.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Joel Becker <joel.becker@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: David Howells <dhowells@redhat.com>
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index f573ac1..5575001 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -108,7 +108,8 @@
 	argv[i] = NULL;
 
 	/* do it */
-	ret = call_usermodehelper_keys(argv[0], argv, envp, keyring, 1);
+	ret = call_usermodehelper_keys(argv[0], argv, envp, keyring,
+				       UMH_WAIT_PROC);
 
 error_link:
 	key_put(keyring);