linux-kernel - [PATCH v12 4/8] xbitmap: add xb_find_next_bit() and xb

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Date:   Wed, 12 Jul 2017 20:40:17 +0800
From:   Wei Wang <wei.w.wang@...el.com>
To:     linux-kernel@...r.kernel.org, qemu-devel@...gnu.org,
        virtualization@...ts.linux-foundation.org, kvm@...r.kernel.org,
        linux-mm@...ck.org, mst@...hat.com, david@...hat.com,
        cornelia.huck@...ibm.com, akpm@...ux-foundation.org,
        mgorman@...hsingularity.net, aarcange@...hat.com,
        amit.shah@...hat.com, pbonzini@...hat.com, wei.w.wang@...el.com,
        liliang.opensource@...il.com
Cc:     virtio-dev@...ts.oasis-open.org, yang.zhang.wz@...il.com,
        quan.xu@...yun.com
Subject: [PATCH v12 4/8] xbitmap: add xb_find_next_bit() and xb_zero()

xb_find_next_bit() is added to support find the next "1" or "0" bit
in the given range. xb_zero() is added to support zero the given range
of bits.

Signed-off-by: Wei Wang <wei.w.wang@...el.com>
---
 include/linux/xbitmap.h |  4 ++++
 lib/radix-tree.c        | 26 ++++++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/include/linux/xbitmap.h b/include/linux/xbitmap.h
index 0b93a46..88c2045 100644
--- a/include/linux/xbitmap.h
+++ b/include/linux/xbitmap.h
@@ -36,6 +36,10 @@ int xb_set_bit(struct xb *xb, unsigned long bit);
 bool xb_test_bit(const struct xb *xb, unsigned long bit);
 int xb_clear_bit(struct xb *xb, unsigned long bit);
 
+void xb_zero(struct xb *xb, unsigned long start, unsigned long end);
+unsigned long xb_find_next_bit(struct xb *xb, unsigned long start,
+			       unsigned long end, bool set);
+
 static inline bool xb_empty(const struct xb *xb)
 {
 	return radix_tree_empty(&xb->xbrt);
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index d624914..c45b910 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -2271,6 +2271,32 @@ bool xb_test_bit(const struct xb *xb, unsigned long bit)
 	return test_bit(bit, bitmap->bitmap);
 }
 
+void xb_zero(struct xb *xb, unsigned long start, unsigned long end)
+{
+	unsigned long i;
+
+	for (i = start; i <= end; i++)
+		xb_clear_bit(xb, i);
+}
+
+/*
+ * Find the next one (@set = 1) or zero (@set = 0) bit within the bit range
+ * from @start to @end in @xb. If no such bit is found in the given range,
+ * bit end + 1 will be returned.
+ */
+unsigned long xb_find_next_bit(struct xb *xb, unsigned long start,
+			       unsigned long end, bool set)
+{
+	unsigned long i;
+
+	for (i = start; i <= end; i++) {
+		if (xb_test_bit(xb, i) == set)
+			break;
+	}
+
+	return i;
+}
+
 void __rcu **idr_get_free(struct radix_tree_root *root,
 			struct radix_tree_iter *iter, gfp_t gfp, int end)
 {
-- 
2.7.4