From: Douglas Anderson dianders@chromium.org
[ Upstream commit 299632e54b2e692d2830af84be51172480dc1e26 ]
If a regmap has "fast_io" set then its lock function uses a spinlock. That doesn't work so well with the functions: * regmap_cache_only_write_file() * regmap_cache_bypass_write_file()
Both of the above functions have the pattern: 1. Lock the regmap. 2. Call: debugfs_write_file_bool() copy_from_user() __might_fault() __might_sleep()
Let's reorder things a bit so that we do all of our sleepable functions before we grab the lock.
Fixes: d3dc5430d68f ("regmap: debugfs: Allow writes to cache state settings") Signed-off-by: Douglas Anderson dianders@chromium.org Link: https://lore.kernel.org/r/20200715164611.1.I35b3533e8a80efde0cec1cc70f71e1e7... Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/base/regmap/regmap-debugfs.c | 52 ++++++++++++++++------------ 1 file changed, 29 insertions(+), 23 deletions(-)
diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c index e72843fe41dfe..e16afa27700db 100644 --- a/drivers/base/regmap/regmap-debugfs.c +++ b/drivers/base/regmap/regmap-debugfs.c @@ -457,29 +457,31 @@ static ssize_t regmap_cache_only_write_file(struct file *file, { struct regmap *map = container_of(file->private_data, struct regmap, cache_only); - ssize_t result; - bool was_enabled, require_sync = false; + bool new_val, require_sync = false; int err;
- map->lock(map->lock_arg); + err = kstrtobool_from_user(user_buf, count, &new_val); + /* Ignore malforned data like debugfs_write_file_bool() */ + if (err) + return count;
- was_enabled = map->cache_only; + err = debugfs_file_get(file->f_path.dentry); + if (err) + return err;
- result = debugfs_write_file_bool(file, user_buf, count, ppos); - if (result < 0) { - map->unlock(map->lock_arg); - return result; - } + map->lock(map->lock_arg);
- if (map->cache_only && !was_enabled) { + if (new_val && !map->cache_only) { dev_warn(map->dev, "debugfs cache_only=Y forced\n"); add_taint(TAINT_USER, LOCKDEP_STILL_OK); - } else if (!map->cache_only && was_enabled) { + } else if (!new_val && map->cache_only) { dev_warn(map->dev, "debugfs cache_only=N forced: syncing cache\n"); require_sync = true; } + map->cache_only = new_val;
map->unlock(map->lock_arg); + debugfs_file_put(file->f_path.dentry);
if (require_sync) { err = regcache_sync(map); @@ -487,7 +489,7 @@ static ssize_t regmap_cache_only_write_file(struct file *file, dev_err(map->dev, "Failed to sync cache %d\n", err); }
- return result; + return count; }
static const struct file_operations regmap_cache_only_fops = { @@ -502,28 +504,32 @@ static ssize_t regmap_cache_bypass_write_file(struct file *file, { struct regmap *map = container_of(file->private_data, struct regmap, cache_bypass); - ssize_t result; - bool was_enabled; + bool new_val; + int err;
- map->lock(map->lock_arg); + err = kstrtobool_from_user(user_buf, count, &new_val); + /* Ignore malforned data like debugfs_write_file_bool() */ + if (err) + return count;
- was_enabled = map->cache_bypass; + err = debugfs_file_get(file->f_path.dentry); + if (err) + return err;
- result = debugfs_write_file_bool(file, user_buf, count, ppos); - if (result < 0) - goto out; + map->lock(map->lock_arg);
- if (map->cache_bypass && !was_enabled) { + if (new_val && !map->cache_bypass) { dev_warn(map->dev, "debugfs cache_bypass=Y forced\n"); add_taint(TAINT_USER, LOCKDEP_STILL_OK); - } else if (!map->cache_bypass && was_enabled) { + } else if (!new_val && map->cache_bypass) { dev_warn(map->dev, "debugfs cache_bypass=N forced\n"); } + map->cache_bypass = new_val;
-out: map->unlock(map->lock_arg); + debugfs_file_put(file->f_path.dentry);
- return result; + return count; }
static const struct file_operations regmap_cache_bypass_fops = {