[3.13.y-ckt stable] Patch "regmap: regcache-rbtree: Clean new present bits on present bitmap resize" has been added to staging queue

Kamal Mostafa kamal at canonical.com
Tue Sep 22 00:32:26 UTC 2015


This is a note to let you know that I have just added a patch titled

    regmap: regcache-rbtree: Clean new present bits on present bitmap resize

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt27.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From e5ffa44fe53316a61531a3926d5324f701caec74 Mon Sep 17 00:00:00 2001
From: Guenter Roeck <linux at roeck-us.net>
Date: Sun, 26 Jul 2015 21:34:50 -0700
Subject: regmap: regcache-rbtree: Clean new present bits on present bitmap
 resize

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 at roeck-us.net>
Signed-off-by: Mark Brown <broonie at kernel.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 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 a6ab1b8..5286087 100644
--- a/drivers/base/regmap/regcache-rbtree.c
+++ b/drivers/base/regmap/regcache-rbtree.c
@@ -296,11 +296,20 @@ 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 */
--
1.9.1





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