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Subject[PATCHv2] regmap: debugfs: Fix a boot time crash with early regmap init
Date
If called early enough, regmap_debugfs_init causes a crash, if the
fs subsystem does not have its mount cache created yet. Even if this
would work, the root node for the regmap debugfs is still missing,
thus postpone the regmap_debugfs_init in this case until the root
node is created. A special regmap_debugfs_early list is created for
this purpose which is parsed later in the boot.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
---
drivers/base/regmap/regmap-debugfs.c | 57 +++++++++++++++++++++++++++++++---
1 file changed, 52 insertions(+), 5 deletions(-)

diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index de11eca..c5471cd 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -15,10 +15,19 @@
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/device.h>
+#include <linux/list.h>

#include "internal.h"

+struct regmap_debugfs_node {
+ struct regmap *map;
+ const char *name;
+ struct list_head link;
+};
+
static struct dentry *regmap_debugfs_root;
+static LIST_HEAD(regmap_debugfs_early_list);
+static DEFINE_MUTEX(regmap_debugfs_early_lock);

/* Calculate the length of a fixed format */
static size_t regmap_calc_reg_len(int max_val, char *buf, size_t buf_size)
@@ -465,6 +474,20 @@ void regmap_debugfs_init(struct regmap *map, const char *name)
struct rb_node *next;
struct regmap_range_node *range_node;

+ /* If we don't have the debugfs root yet, postpone init */
+ if (!regmap_debugfs_root) {
+ struct regmap_debugfs_node *node;
+ node = kzalloc(sizeof(*node), GFP_KERNEL);
+ if (!node)
+ return;
+ node->map = map;
+ node->name = name;
+ mutex_lock(&regmap_debugfs_early_lock);
+ list_add(&node->link, &regmap_debugfs_early_list);
+ mutex_unlock(&regmap_debugfs_early_lock);
+ return;
+ }
+
INIT_LIST_HEAD(&map->debugfs_off_cache);
mutex_init(&map->cache_lock);

@@ -519,18 +542,42 @@ 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);
+ if (map->debugfs) {
+ 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);
+ } else {
+ struct regmap_debugfs_node *node, *tmp;
+
+ mutex_lock(&regmap_debugfs_early_lock);
+ list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list,
+ link) {
+ if (node->map == map) {
+ list_del(&node->link);
+ kfree(node);
+ }
+ }
+ mutex_unlock(&regmap_debugfs_early_lock);
+ }
}

void regmap_debugfs_initcall(void)
{
+ struct regmap_debugfs_node *node, *tmp;
+
regmap_debugfs_root = debugfs_create_dir("regmap", NULL);
if (!regmap_debugfs_root) {
pr_warn("regmap: Failed to create debugfs root\n");
return;
}
+
+ mutex_lock(&regmap_debugfs_early_lock);
+ list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list, link) {
+ regmap_debugfs_init(node->map, node->name);
+ list_del(&node->link);
+ kfree(node);
+ }
+ mutex_unlock(&regmap_debugfs_early_lock);
}
--
1.7.9.5


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