Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit ebd74a77 authored by Douglas Anderson's avatar Douglas Anderson Committed by Greg Kroah-Hartman
Browse files

regmap: debugfs: Don't sleep while atomic for fast_io regmaps 



[ 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: d3dc5430 ("regmap: debugfs: Allow writes to cache state settings")
Signed-off-by: default avatarDouglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20200715164611.1.I35b3533e8a80efde0cec1cc70f71e1e74b2fa0da@changeid


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 970354a3

drivers/base/regmap/regmap-debugfs.c

+29 −23
Original line number Diff line number Diff line
@@ -453,29 +453,31 @@ 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);
@@ -483,7 +485,7 @@ 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 = {
@@ -498,28 +500,32 @@ 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 = {