crypto: xor - defer load time benchmark to a later time

Currently, the XOR module performs its boot time benchmark at core
initcall time when it is built-in, to ensure that the RAID code can
make use of it when it is built-in as well.

Let's defer this to a later stage during the boot, to avoid impacting
the overall boot time of the system. Instead, just pick an arbitrary
implementation from the list, and use that as the preliminary default.
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/xor.c

@@ -54,6 +54,28 @@ EXPORT_SYMBOL(xor_blocks);
 /* Set of all registered templates.  */
 static struct xor_block_template *__initdata template_list;
 
+#ifndef MODULE
+static void __init do_xor_register(struct xor_block_template *tmpl)
+{
+	tmpl->next = template_list;
+	template_list = tmpl;
+}
+
+static int __init register_xor_blocks(void)
+{
+	active_template = XOR_SELECT_TEMPLATE(NULL);
+
+	if (!active_template) {
+#define xor_speed	do_xor_register
+		// register all the templates and pick the first as the default
+		XOR_TRY_TEMPLATES;
+#undef xor_speed
+		active_template = template_list;
+	}
+	return 0;
+}
+#endif
+
 #define BENCH_SIZE (PAGE_SIZE)
 
 static void __init
@@ -129,6 +151,7 @@ calibrate_xor_blocks(void)
 #define xor_speed(templ)	do_xor_speed((templ), b1, b2)
 
 	printk(KERN_INFO "xor: measuring software checksum speed\n");
+	template_list = NULL;
 	XOR_TRY_TEMPLATES;
 	fastest = template_list;
 	for (f = fastest; f; f = f->next)
@@ -150,6 +173,10 @@ static __exit void xor_exit(void) { }
 
 MODULE_LICENSE("GPL");
 
+#ifndef MODULE
 /* when built-in xor.o must initialize before drivers/md/md.o */
-core_initcall(calibrate_xor_blocks);
+core_initcall(register_xor_blocks);
+#endif
+
+module_init(calibrate_xor_blocks);
 module_exit(xor_exit);