init: remove CONFIG_INIT_FALLBACK

CONFIG_INIT_FALLBACK adds config bloat without an obvious use case that
makes it worth keeping around.  Delete it.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Chuck Ebbert <cebbert.lkml@gmail.com>
Cc: Frank Rowand <frowand.list@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Rob Landley <rob@landley.net>
Cc: Shuah Khan <shuah.kh@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

init/Kconfig

@@ -1287,22 +1287,6 @@ source "usr/Kconfig"
 
 endif
 
-config INIT_FALLBACK
-	bool "Fall back to defaults if init= parameter is bad"
-	default y
-	help
-	  If enabled, the kernel will try the default init binaries if an
-	  explicit request from the init= parameter fails.
-
-	  This can have unexpected effects.  For example, booting
-	  with init=/sbin/kiosk_app will run /sbin/init or even /bin/sh
-	  if /sbin/kiosk_app cannot be executed.
-
-	  The default value of Y is consistent with historical behavior.
-	  Selecting N is likely to be more appropriate for most uses,
-	  especially on kiosks and on kernels that are intended to be
-	  run under the control of a script.
-
 config CC_OPTIMIZE_FOR_SIZE
 	bool "Optimize for size"
 	help

init/main.c

@@ -953,13 +953,8 @@ static int __ref kernel_init(void *unused)
 		ret = run_init_process(execute_command);
 		if (!ret)
 			return 0;
-#ifndef CONFIG_INIT_FALLBACK
 		panic("Requested init %s failed (error %d).",
 		      execute_command, ret);
-#else
-		pr_err("Failed to execute %s (error %d).  Attempting defaults...\n",
-		       execute_command, ret);
-#endif
 	}
 	if (!try_to_run_init_process("/sbin/init") ||
 	    !try_to_run_init_process("/etc/init") ||