lmb: Add lmb_free()

We can free memory allocated with lmb_alloc() by removing it from the
list of reserved LMBs. Rework lmb_remove() to allow that possibility
and add lmb_free() which exploits it.

BenH: Removed some useless parenthesis

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

include/linux/lmb.h

@@ -42,6 +42,7 @@ extern void __init lmb_init(void);
 extern void __init lmb_analyze(void);
 extern long lmb_add(u64 base, u64 size);
 extern long lmb_remove(u64 base, u64 size);
+extern long __init lmb_free(u64 base, u64 size);
 extern long __init lmb_reserve(u64 base, u64 size);
 extern u64 __init lmb_alloc_nid(u64 size, u64 align, int nid,
 				u64 (*nid_range)(u64, u64, int *));

lib/lmb.c

@@ -205,9 +205,8 @@ long lmb_add(u64 base, u64 size)
 
 }
 
-long lmb_remove(u64 base, u64 size)
+static long __lmb_remove(struct lmb_region *rgn, u64 base, u64 size)
 {
-	struct lmb_region *rgn = &(lmb.memory);
 	u64 rgnbegin, rgnend;
 	u64 end = base + size;
 	int i;
@@ -254,6 +253,16 @@ long lmb_remove(u64 base, u64 size)
 	return lmb_add_region(rgn, end, rgnend - end);
 }
 
+long lmb_remove(u64 base, u64 size)
+{
+	return __lmb_remove(&lmb.memory, base, size);
+}
+
+long __init lmb_free(u64 base, u64 size)
+{
+	return __lmb_remove(&lmb.reserved, base, size);
+}
+
 long __init lmb_reserve(u64 base, u64 size)
 {
 	struct lmb_region *_rgn = &lmb.reserved;