linux-kernel - [PATCH] regmap: Fix cache defaults initialization from raw cache defaults

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 15 Feb 2012 10:23:25 +0100
From:	Lars-Peter Clausen <lars@...afoo.de>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	linux-kernel@...r.kernel.org, Lars-Peter Clausen <lars@...afoo.de>
Subject: [PATCH] regmap: Fix cache defaults initialization from raw cache defaults

Currently registers with a value of 0 are ignored when initializing the register
defaults from raw defaults. This worked in the past, because registers without a
explicit default were assumed to have a default value of 0. This was changed in
commit b03622a8 ("regmap: Ensure rbtree syncs registers set to zero properly").
As a result registers, which have a raw default value of 0 are now assumed to
have no default. This again can result in unnecessary writes when syncing the
cache. It will also result in unnecessary reads for e.g. the first update
operation. In the case where readback is not possible this will even let the
update operation fail, if the register has not been written to before.

So this patch removes the check. Instead it adds a check to ignore raw defaults
for registers which are volatile, since those registers are not cached.

Signed-off-by: Lars-Peter Clausen <lars@...afoo.de>
---
 drivers/base/regmap/regcache.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index 77ce5ff..a10e81c 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -53,7 +53,7 @@ static int regcache_hw_init(struct regmap *map)
 	for (count = 0, i = 0; i < map->num_reg_defaults_raw; i++) {
 		val = regcache_get_val(map->reg_defaults_raw,
 				       i, map->cache_word_size);
-		if (!val)
+		if (regmap_volatile(map, i))
 			continue;
 		count++;
 	}
@@ -70,7 +70,7 @@ static int regcache_hw_init(struct regmap *map)
 	for (i = 0, j = 0; i < map->num_reg_defaults_raw; i++) {
 		val = regcache_get_val(map->reg_defaults_raw,
 				       i, map->cache_word_size);
-		if (!val)
+		if (regmap_volatile(map, i))
 			continue;
 		map->reg_defaults[j].reg = i;
 		map->reg_defaults[j].def = val;
-- 
1.7.9

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/