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Date: Thu, 14 Feb 2013 12:31:48 +0000
From: Dimitris Papastamos <dp@...nsource.wolfsonmicro.com>
To: Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc: linux-kernel@...r.kernel.org, patches@...nsource.wolfsonmicro.com
Subject: [PATCH 2/2] regmap: debugfs: Ensure proper locking of `debugfs_off_cache' list
There is a possible race between the read operations of the `registers'
file and the `range' file. Close that down by taking the appropriate
locks when modifying/accessing the list.
Signed-off-by: Dimitris Papastamos <dp@...nsource.wolfsonmicro.com>
---
drivers/base/regmap/internal.h | 1 +
drivers/base/regmap/regmap-debugfs.c | 10 ++++++++++
2 files changed, 11 insertions(+)
diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index b4e55a0..640c5a4 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -77,6 +77,7 @@ struct regmap {
unsigned int debugfs_tot_len;
struct list_head debugfs_off_cache;
+ struct mutex cache_lock;
#endif
unsigned int max_register;
diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index 5843eb1..89a5a85 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -76,6 +76,7 @@ static inline unsigned int regmap_attr_bitmap(struct regmap *map,
return reg_attr;
}
+/* Called with `cache_lock' held */
static void regmap_debugfs_free_dump_cache(struct regmap *map)
{
struct regmap_debugfs_off_cache *c;
@@ -108,6 +109,7 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
* If we don't have a cache build one so we don't have to do a
* linear scan each time.
*/
+ mutex_lock(&map->cache_lock);
if (list_empty(&map->debugfs_off_cache)) {
for (i = base; i <= map->max_register; i += map->reg_stride) {
/* Skip unprinted registers, closing off cache entry */
@@ -130,6 +132,7 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
c = kzalloc(sizeof(*c), GFP_KERNEL);
if (!c) {
regmap_debugfs_free_dump_cache(map);
+ mutex_unlock(&map->cache_lock);
return base;
}
c->min = p;
@@ -163,12 +166,14 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
fpos_offset = from - c->min;
reg_offset = fpos_offset / map->debugfs_tot_len;
*pos = c->min + (reg_offset * map->debugfs_tot_len);
+ mutex_unlock(&map->cache_lock);
return c->base_reg + reg_offset;
}
*pos = c->max;
ret = c->max_reg;
}
+ mutex_unlock(&map->cache_lock);
return ret;
}
@@ -392,6 +397,7 @@ static ssize_t regmap_reg_ranges_read_file(struct file *file,
/* Reset file pointer as the fixed-format of the `registers'
* file is not compatible with the `range' file */
p = 0;
+ mutex_lock(&map->cache_lock);
list_for_each_entry(c, &map->debugfs_off_cache, list) {
regmap_range_format_line(map, c, entry, PAGE_SIZE);
if (p >= *ppos) {
@@ -405,6 +411,7 @@ static ssize_t regmap_reg_ranges_read_file(struct file *file,
}
p += strlen(entry) + 1;
}
+ mutex_unlock(&map->cache_lock);
kfree(entry);
ret = buf_pos;
@@ -500,6 +507,7 @@ void regmap_debugfs_init(struct regmap *map, const char *name)
struct regmap_range_node *range_node;
INIT_LIST_HEAD(&map->debugfs_off_cache);
+ mutex_init(&map->cache_lock);
if (name) {
map->debugfs_name = kasprintf(GFP_KERNEL, "%s-%s",
@@ -553,7 +561,9 @@ void regmap_debugfs_init(struct regmap *map, const char *name)
void regmap_debugfs_exit(struct regmap *map)
{
debugfs_remove_recursive(map->debugfs);
+ mutex_lock(&map->cache_lock);
regmap_debugfs_free_dump_cache(map);
+ mutex_unlock(&map->cache_lock);
kfree(map->debugfs_name);
}
--
1.8.1.3
--
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