1. Patchew
  2. linux
  3. [PATCH 0/3] i2c: atr: A few i2c-atr fixes
  4. View patch

[PATCH 2/3] i2c: atr: Fix lockdep for nested ATRs

Tomi Valkeinen posted 3 patches 1 year, 2 months ago
There is a newer version of this series
[PATCH 2/3] i2c: atr: Fix lockdep for nested ATRs
Posted by Tomi Valkeinen 1 year, 2 months ago 
From: Tomi Valkeinen <tomi.valkeinen+renesas@ideasonboard.com>

When we have an ATR, and another ATR as a subdevice of the first ATR,
we get lockdep warnings for the i2c_atr.lock and
i2c_atr_chan.orig_addrs_lock. This is because lockdep uses a static key
for the locks, and doesn't see the locks of the separate ATR instances
as separate.

Fix this by generating a dynamic lock key per lock instance.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas@ideasonboard.com>
---
 drivers/i2c/i2c-atr.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/i2c/i2c-atr.c b/drivers/i2c/i2c-atr.c
index ef5adafa9bf4..9bdbd94b5054 100644
--- a/drivers/i2c/i2c-atr.c
+++ b/drivers/i2c/i2c-atr.c
@@ -54,6 +54,7 @@ struct i2c_atr_chan {
 
 	/* Lock orig_addrs during xfer */
 	struct mutex orig_addrs_lock;
+	struct lock_class_key orig_addrs_lock_key;
 	u16 *orig_addrs;
 	unsigned int orig_addrs_size;
 };
@@ -84,6 +85,7 @@ struct i2c_atr {
 	struct i2c_algorithm algo;
 	/* lock for the I2C bus segment (see struct i2c_lock_operations) */
 	struct mutex lock;
+	struct lock_class_key lock_key;
 	int max_adapters;
 
 	size_t num_aliases;
@@ -505,7 +507,10 @@ struct i2c_atr *i2c_atr_new(struct i2c_adapter *parent, struct device *dev,
 	if (!atr)
 		return ERR_PTR(-ENOMEM);
 
+	lockdep_register_key(&atr->lock_key);
 	mutex_init(&atr->lock);
+	lockdep_set_class(&atr->lock, &atr->lock_key);
+
 	spin_lock_init(&atr->alias_mask_lock);
 
 	atr->parent = parent;
@@ -535,6 +540,7 @@ struct i2c_atr *i2c_atr_new(struct i2c_adapter *parent, struct device *dev,
 	kfree(atr->aliases);
 err_destroy_mutex:
 	mutex_destroy(&atr->lock);
+	lockdep_unregister_key(&atr->lock_key);
 	kfree(atr);
 
 	return ERR_PTR(ret);
@@ -552,6 +558,7 @@ void i2c_atr_delete(struct i2c_atr *atr)
 	bitmap_free(atr->alias_use_mask);
 	kfree(atr->aliases);
 	mutex_destroy(&atr->lock);
+	lockdep_unregister_key(&atr->lock_key);
 	kfree(atr);
 }
 EXPORT_SYMBOL_NS_GPL(i2c_atr_delete, I2C_ATR);
@@ -586,7 +593,9 @@ int i2c_atr_add_adapter(struct i2c_atr *atr, u32 chan_id,
 	chan->atr = atr;
 	chan->chan_id = chan_id;
 	INIT_LIST_HEAD(&chan->alias_list);
+	lockdep_register_key(&chan->orig_addrs_lock_key);
 	mutex_init(&chan->orig_addrs_lock);
+	lockdep_set_class(&chan->orig_addrs_lock, &chan->orig_addrs_lock_key);
 
 	snprintf(chan->adap.name, sizeof(chan->adap.name), "i2c-%d-atr-%d",
 		 i2c_adapter_id(parent), chan_id);
@@ -646,6 +655,7 @@ int i2c_atr_add_adapter(struct i2c_atr *atr, u32 chan_id,
 err_fwnode_put:
 	fwnode_handle_put(dev_fwnode(&chan->adap.dev));
 	mutex_destroy(&chan->orig_addrs_lock);
+	lockdep_unregister_key(&chan->orig_addrs_lock_key);
 	kfree(chan);
 	return ret;
 }
@@ -679,6 +689,7 @@ void i2c_atr_del_adapter(struct i2c_atr *atr, u32 chan_id)
 
 	fwnode_handle_put(fwnode);
 	mutex_destroy(&chan->orig_addrs_lock);
+	lockdep_unregister_key(&chan->orig_addrs_lock_key);
 	kfree(chan->orig_addrs);
 	kfree(chan);
 }

-- 
2.43.0
Re: [PATCH 2/3] i2c: atr: Fix lockdep for nested ATRs
Posted by kernel test robot 1 year, 2 months ago 
Hi Tomi,

kernel test robot noticed the following build warnings:

[auto build test WARNING on adc218676eef25575469234709c2d87185ca223a]

url:    https://github.com/intel-lab-lkp/linux/commits/Tomi-Valkeinen/i2c-atr-Allow-unmapped-addresses-from-nested-ATRs/20241125-104419
base:   adc218676eef25575469234709c2d87185ca223a
patch link:    https://lore.kernel.org/r/20241122-i2c-atr-fixes-v1-2-62c51ce790be%40ideasonboard.com
patch subject: [PATCH 2/3] i2c: atr: Fix lockdep for nested ATRs
config: i386-buildonly-randconfig-001-20241125 (https://download.01.org/0day-ci/archive/20241125/202411252015.N7sBYvri-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241125/202411252015.N7sBYvri-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202411252015.N7sBYvri-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/i2c/i2c-atr.c:60: warning: Function parameter or struct member 'orig_addrs_lock_key' not described in 'i2c_atr_chan'
>> drivers/i2c/i2c-atr.c:100: warning: Function parameter or struct member 'lock_key' not described in 'i2c_atr'


vim +60 drivers/i2c/i2c-atr.c

a076a860acae77 Luca Ceresoli  2023-06-19   36  
a076a860acae77 Luca Ceresoli  2023-06-19   37  /**
a076a860acae77 Luca Ceresoli  2023-06-19   38   * struct i2c_atr_chan - Data for a channel.
a076a860acae77 Luca Ceresoli  2023-06-19   39   * @adap:            The &struct i2c_adapter for the channel
a076a860acae77 Luca Ceresoli  2023-06-19   40   * @atr:             The parent I2C ATR
a076a860acae77 Luca Ceresoli  2023-06-19   41   * @chan_id:         The ID of this channel
a076a860acae77 Luca Ceresoli  2023-06-19   42   * @alias_list:      List of @struct i2c_atr_alias_pair containing the
a076a860acae77 Luca Ceresoli  2023-06-19   43   *                   assigned aliases
a076a860acae77 Luca Ceresoli  2023-06-19   44   * @orig_addrs_lock: Mutex protecting @orig_addrs
a076a860acae77 Luca Ceresoli  2023-06-19   45   * @orig_addrs:      Buffer used to store the original addresses during transmit
a076a860acae77 Luca Ceresoli  2023-06-19   46   * @orig_addrs_size: Size of @orig_addrs
a076a860acae77 Luca Ceresoli  2023-06-19   47   */
a076a860acae77 Luca Ceresoli  2023-06-19   48  struct i2c_atr_chan {
a076a860acae77 Luca Ceresoli  2023-06-19   49  	struct i2c_adapter adap;
a076a860acae77 Luca Ceresoli  2023-06-19   50  	struct i2c_atr *atr;
a076a860acae77 Luca Ceresoli  2023-06-19   51  	u32 chan_id;
a076a860acae77 Luca Ceresoli  2023-06-19   52  
a076a860acae77 Luca Ceresoli  2023-06-19   53  	struct list_head alias_list;
a076a860acae77 Luca Ceresoli  2023-06-19   54  
a076a860acae77 Luca Ceresoli  2023-06-19   55  	/* Lock orig_addrs during xfer */
a076a860acae77 Luca Ceresoli  2023-06-19   56  	struct mutex orig_addrs_lock;
f2d3b6b436282b Tomi Valkeinen 2024-11-22   57  	struct lock_class_key orig_addrs_lock_key;
a076a860acae77 Luca Ceresoli  2023-06-19   58  	u16 *orig_addrs;
a076a860acae77 Luca Ceresoli  2023-06-19   59  	unsigned int orig_addrs_size;
a076a860acae77 Luca Ceresoli  2023-06-19  @60  };
a076a860acae77 Luca Ceresoli  2023-06-19   61  
a076a860acae77 Luca Ceresoli  2023-06-19   62  /**
a076a860acae77 Luca Ceresoli  2023-06-19   63   * struct i2c_atr - The I2C ATR instance
a076a860acae77 Luca Ceresoli  2023-06-19   64   * @parent:    The parent &struct i2c_adapter
a076a860acae77 Luca Ceresoli  2023-06-19   65   * @dev:       The device that owns the I2C ATR instance
a076a860acae77 Luca Ceresoli  2023-06-19   66   * @ops:       &struct i2c_atr_ops
a076a860acae77 Luca Ceresoli  2023-06-19   67   * @priv:      Private driver data, set with i2c_atr_set_driver_data()
a076a860acae77 Luca Ceresoli  2023-06-19   68   * @algo:      The &struct i2c_algorithm for adapters
a076a860acae77 Luca Ceresoli  2023-06-19   69   * @lock:      Lock for the I2C bus segment (see &struct i2c_lock_operations)
a076a860acae77 Luca Ceresoli  2023-06-19   70   * @max_adapters: Maximum number of adapters this I2C ATR can have
a076a860acae77 Luca Ceresoli  2023-06-19   71   * @num_aliases: Number of aliases in the aliases array
a076a860acae77 Luca Ceresoli  2023-06-19   72   * @aliases:   The aliases array
a076a860acae77 Luca Ceresoli  2023-06-19   73   * @alias_mask_lock: Lock protecting alias_use_mask
a076a860acae77 Luca Ceresoli  2023-06-19   74   * @alias_use_mask: Bitmask for used aliases in aliases array
a076a860acae77 Luca Ceresoli  2023-06-19   75   * @i2c_nb:    Notifier for remote client add & del events
a076a860acae77 Luca Ceresoli  2023-06-19   76   * @adapter:   Array of adapters
a076a860acae77 Luca Ceresoli  2023-06-19   77   */
a076a860acae77 Luca Ceresoli  2023-06-19   78  struct i2c_atr {
a076a860acae77 Luca Ceresoli  2023-06-19   79  	struct i2c_adapter *parent;
a076a860acae77 Luca Ceresoli  2023-06-19   80  	struct device *dev;
a076a860acae77 Luca Ceresoli  2023-06-19   81  	const struct i2c_atr_ops *ops;
a076a860acae77 Luca Ceresoli  2023-06-19   82  
a076a860acae77 Luca Ceresoli  2023-06-19   83  	void *priv;
a076a860acae77 Luca Ceresoli  2023-06-19   84  
a076a860acae77 Luca Ceresoli  2023-06-19   85  	struct i2c_algorithm algo;
a076a860acae77 Luca Ceresoli  2023-06-19   86  	/* lock for the I2C bus segment (see struct i2c_lock_operations) */
a076a860acae77 Luca Ceresoli  2023-06-19   87  	struct mutex lock;
f2d3b6b436282b Tomi Valkeinen 2024-11-22   88  	struct lock_class_key lock_key;
a076a860acae77 Luca Ceresoli  2023-06-19   89  	int max_adapters;
a076a860acae77 Luca Ceresoli  2023-06-19   90  
a076a860acae77 Luca Ceresoli  2023-06-19   91  	size_t num_aliases;
a076a860acae77 Luca Ceresoli  2023-06-19   92  	const u16 *aliases;
a076a860acae77 Luca Ceresoli  2023-06-19   93  	/* Protects alias_use_mask */
a076a860acae77 Luca Ceresoli  2023-06-19   94  	spinlock_t alias_mask_lock;
a076a860acae77 Luca Ceresoli  2023-06-19   95  	unsigned long *alias_use_mask;
a076a860acae77 Luca Ceresoli  2023-06-19   96  
a076a860acae77 Luca Ceresoli  2023-06-19   97  	struct notifier_block i2c_nb;
a076a860acae77 Luca Ceresoli  2023-06-19   98  
3a133a4e44554b Kees Cook      2023-09-22   99  	struct i2c_adapter *adapter[] __counted_by(max_adapters);
a076a860acae77 Luca Ceresoli  2023-06-19 @100  };
a076a860acae77 Luca Ceresoli  2023-06-19  101  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
Re: [PATCH 2/3] i2c: atr: Fix lockdep for nested ATRs
Posted by Andy Shevchenko 1 year, 2 months ago 
On Fri, Nov 22, 2024 at 09:51:39AM +0200, Tomi Valkeinen wrote:
> From: Tomi Valkeinen <tomi.valkeinen+renesas@ideasonboard.com>
> 
> When we have an ATR, and another ATR as a subdevice of the first ATR,
> we get lockdep warnings for the i2c_atr.lock and
> i2c_atr_chan.orig_addrs_lock. This is because lockdep uses a static key
> for the locks, and doesn't see the locks of the separate ATR instances
> as separate.

...

> +	lockdep_register_key(&atr->lock_key);
>  	mutex_init(&atr->lock);
> +	lockdep_set_class(&atr->lock, &atr->lock_key);

mutext_init_with_key()

...

> +	lockdep_register_key(&chan->orig_addrs_lock_key);
>  	mutex_init(&chan->orig_addrs_lock);
> +	lockdep_set_class(&chan->orig_addrs_lock, &chan->orig_addrs_lock_key);

Ditto.

-- 
With Best Regards,
Andy Shevchenko

Patchew 2.1-devel-b67e4c2

© 2016 - 2026 Red Hat, Inc.