linux-kernel - [PATCH 3.12 08/84] regmap: regcache-rbtree: Clean new present bits on present bitmap resize

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Message-Id: <f71e250f45c8419f6cbdb3e9e36ee7a1138ec598.1443792303.git.jslaby@suse.cz>
Date:	Fri,  2 Oct 2015 15:24:13 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>,
	Mark Brown <broonie@...nel.org>, Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 08/84] regmap: regcache-rbtree: Clean new present bits on present bitmap resize

From: Guenter Roeck <linux@...ck-us.net>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 8ef9724bf9718af81cfc5132253372f79c71b7e2 upstream.

When inserting a new register into a block, the present bit map size is
increased using krealloc. krealloc does not clear the additionally
allocated memory, leaving it filled with random values. Result is that
some registers are considered cached even though this is not the case.

Fix the problem by clearing the additionally allocated memory. Also, if
the bitmap size does not increase, do not reallocate the bitmap at all
to reduce overhead.

Fixes: 3f4ff561bc88 ("regmap: rbtree: Make cache_present bitmap per node")
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 drivers/base/regmap/regcache-rbtree.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/base/regmap/regcache-rbtree.c b/drivers/base/regmap/regcache-rbtree.c
index 2b946bc4212d..f3f71369adc7 100644
--- a/drivers/base/regmap/regcache-rbtree.c
+++ b/drivers/base/regmap/regcache-rbtree.c
@@ -302,11 +302,20 @@ static int regcache_rbtree_insert_to_block(struct regmap *map,
 	if (!blk)
 		return -ENOMEM;
 
-	present = krealloc(rbnode->cache_present,
-		    BITS_TO_LONGS(blklen) * sizeof(*present), GFP_KERNEL);
-	if (!present) {
-		kfree(blk);
-		return -ENOMEM;
+	if (BITS_TO_LONGS(blklen) > BITS_TO_LONGS(rbnode->blklen)) {
+		present = krealloc(rbnode->cache_present,
+				   BITS_TO_LONGS(blklen) * sizeof(*present),
+				   GFP_KERNEL);
+		if (!present) {
+			kfree(blk);
+			return -ENOMEM;
+		}
+
+		memset(present + BITS_TO_LONGS(rbnode->blklen), 0,
+		       (BITS_TO_LONGS(blklen) - BITS_TO_LONGS(rbnode->blklen))
+		       * sizeof(*present));
+	} else {
+		present = rbnode->cache_present;
 	}
 
 	/* insert the register value in the correct place in the rbnode block */
-- 
2.6.0

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