[POWERPC] Limit range of __init_ref_ok somewhat

This patch introduces zalloc_maybe_bootmem and uses it so that we don't
have to mark a whole (largish) routine as __init_ref_ok.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/lib/alloc.c b/arch/powerpc/lib/alloc.c
index e58c805..f53e09c 100644
--- a/arch/powerpc/lib/alloc.c
+++ b/arch/powerpc/lib/alloc.c
@@ -2,6 +2,7 @@
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/bootmem.h>
+#include <linux/string.h>
 
 #include <asm/system.h>
 
@@ -12,3 +13,17 @@
 	else
 		return alloc_bootmem(size);
 }
+
+void * __init_refok zalloc_maybe_bootmem(size_t size, gfp_t mask)
+{
+	void *p;
+
+	if (mem_init_done)
+		p = kzalloc(size, mask);
+	else {
+		p = alloc_bootmem(size);
+		if (p)
+			memset(p, 0, size);
+	}
+	return p;
+}