linux-kernel - [PATCH v4 06/14] tools bitmap: add bitmap

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Date:   Tue,  4 Aug 2020 20:10:35 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     torvalds@...ux-foundation.org
Cc:     mingo@...nel.org, peterz@...radead.org,
        linux-kernel@...r.kernel.org, Sasha Levin <sashal@...nel.org>
Subject: [PATCH v4 06/14] tools bitmap: add bitmap_clear definition

This is needed as a result of de4643a77356 ("locking/lockdep: Reuse lock
chains that have been freed").

Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 tools/lib/bitmap.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/tools/lib/bitmap.c b/tools/lib/bitmap.c
index b6bc037623fc1..873176c501e43 100644
--- a/tools/lib/bitmap.c
+++ b/tools/lib/bitmap.c
@@ -101,3 +101,23 @@ int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
 			BITMAP_LAST_WORD_MASK(bits));
 	return result != 0;
 }
+
+void bitmap_clear(unsigned long *map, unsigned int start, int len)
+{
+	unsigned long *p = map + BIT_WORD(start);
+	const unsigned int size = start + len;
+	int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
+	unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
+
+	while (len - bits_to_clear >= 0) {
+		*p &= ~mask_to_clear;
+		len -= bits_to_clear;
+		bits_to_clear = BITS_PER_LONG;
+		mask_to_clear = ~0UL;
+		p++;
+	}
+	if (len) {
+		mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
+		*p &= ~mask_to_clear;
+	}
+}
-- 
2.25.1