linux-kernel - Re: [PATCH] regmap: don't corrupt work buffer in _regmap_raw

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Message-ID: <1365416662.1830.86.camel@x61.thuisdomein>
Date:	Mon, 08 Apr 2013 12:24:22 +0200
From:	Paul Bolle <pebolle@...cali.nl>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	Stephen Warren <swarren@...dotorg.org>,
	linux-kernel@...r.kernel.org, Stephen Warren <swarren@...dia.com>,
	Laxman Dewangan <ldewangan@...dia.com>
Subject: Re: [PATCH] regmap: don't corrupt work buffer in _regmap_raw_write()

On Thu, 2013-03-21 at 20:09 +0100, Mark Brown wrote:
> On Wed, Mar 20, 2013 at 05:02:02PM -0600, Stephen Warren wrote:
> > _regmap_raw_write() contains code to call regcache_write() to write
> > values to the cache. That code calls memcpy() to copy the value data to
> > the start of the work_buf. However, at least when _regmap_raw_write() is
> 
> Applied, thanks.

0) This patch ended up as mainline commit
bc8ce4afd7ee7e1421c935d24b1f879f82afdd4e, which is part of v3.9-rc6.

1) Building regmap.o now triggers this warning:
    drivers/base/regmap/regmap.c: In function ‘_regmap_raw_write’:
    drivers/base/regmap/regmap.c:946:4: warning: passing argument 1 of ‘map->format.parse_val’ discards ‘const’ qualifier from pointer target type [enabled by default]
    drivers/base/regmap/regmap.c:946:4: note: expected ‘void *’ but argument is of type ‘const void *’

2) The following (draft) patch silences this warning. I'm a bit
uncertain what the regmap_parse_*() functions are meant to do. So I'd
like to first ask whether something along these lines is acceptable.


Paul Bolle

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index 5a22bd3..35877b7 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -38,7 +38,7 @@ struct regmap_format {
                             unsigned int reg, unsigned int val);
        void (*format_reg)(void *buf, unsigned int reg, unsigned int shift);
        void (*format_val)(void *buf, unsigned int val, unsigned int shift);
-       unsigned int (*parse_val)(void *buf);
+       unsigned int (*parse_val)(const void *buf);
 };
 
 struct regmap_async {
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index d34adef..2ca90a6 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -228,30 +228,28 @@ static void regmap_format_32_native(void *buf, unsigned int val,
        *(u32 *)buf = val << shift;
 }
 
-static unsigned int regmap_parse_8(void *buf)
+static unsigned int regmap_parse_8(const void *buf)
 {
-       u8 *b = buf;
+       const u8 *b = buf;
 
        return b[0];
 }
 
-static unsigned int regmap_parse_16_be(void *buf)
+static unsigned int regmap_parse_16_be(const void *buf)
 {
-       __be16 *b = buf;
+       const __be16 *b = buf;
 
-       b[0] = be16_to_cpu(b[0]);
-
-       return b[0];
+       return be16_to_cpu(b[0]);
 }
 
-static unsigned int regmap_parse_16_native(void *buf)
+static unsigned int regmap_parse_16_native(const void *buf)
 {
        return *(u16 *)buf;
 }
 
-static unsigned int regmap_parse_24(void *buf)
+static unsigned int regmap_parse_24(const void *buf)
 {
-       u8 *b = buf;
+       const u8 *b = buf;
        unsigned int ret = b[2];
        ret |= ((unsigned int)b[1]) << 8;
        ret |= ((unsigned int)b[0]) << 16;
@@ -259,16 +257,14 @@ static unsigned int regmap_parse_24(void *buf)
        return ret;
 }
 
-static unsigned int regmap_parse_32_be(void *buf)
+static unsigned int regmap_parse_32_be(const void *buf)
 {
-       __be32 *b = buf;
+       const __be32 *b = buf;
 
-       b[0] = be32_to_cpu(b[0]);
-
-       return b[0];
+       return be32_to_cpu(b[0]);
 }
 
-static unsigned int regmap_parse_32_native(void *buf)
+static unsigned int regmap_parse_32_native(const void *buf)
 {
        return *(u32 *)buf;
 }


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