linux-kernel - Re: [PATCH V3 1/4] regmap: Use regcache_mark_dirty() to indicate power loss or reset

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

Date:	Mon, 4 May 2015 07:05:38 -0700
From:	Kevin Cernekee <cernekee@...omium.org>
To:	Lars-Peter Clausen <lars@...afoo.de>
Cc:	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>, dgreid@...omium.org,
	Andrew Bresticker <abrestic@...omium.org>,
	Olof Johansson <olofj@...omium.org>,
	alsa-devel@...a-project.org, devicetree@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V3 1/4] regmap: Use regcache_mark_dirty() to indicate
 power loss or reset

On Sun, May 3, 2015 at 11:38 PM, Lars-Peter Clausen <lars@...afoo.de> wrote:
>> diff --git a/drivers/base/regmap/regcache.c
>> b/drivers/base/regmap/regcache.c
>> index 7eb7b3b98794..63af3103d0c6 100644
>> --- a/drivers/base/regmap/regcache.c
>> +++ b/drivers/base/regmap/regcache.c
>> @@ -253,6 +253,9 @@ static int regcache_default_sync(struct regmap *map,
>> unsigned int min,
>>                                  unsigned int max)
>>   {
>>         unsigned int reg;
>> +       bool no_sync_defaults = map->no_sync_defaults;
>> +
>> +       map->no_sync_defaults = false;
>
>
> This needs to be done at the end in regcache_sync(), the same place where
> dirty is set to false.

But map->cache_dirty means "any register is dirty," not "all registers
are dirty."  So it can only be cleared after a successful flush.

If one of the writes fails and regcache_sync() has to return
prematurely, we probably don't want no_sync_defaults to stay true
because some of the HW registers might not match map->reg_defaults
anymore.

Leaving it set to true wouldn't break the current regcache_sync()
implementation, but no_sync_defaults is documented as: "if set, the HW
registers are known to match map->reg_defaults".  Writing any register
to a non-default value makes it false.
--
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/