[PATCH v2] i2c: move locking operations to their own struct

[Wolfram Sang]

On Thu, Aug 25, 2016 at 11:07:01PM +0200, Peter Rosin wrote:
> This makes it trivial to constify them, so do that.
> 
> Signed-off-by: Peter Rosin 

Applied to for-next, thanks! Thanks for the quick ack, Daniel!

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[PATCH v2] i2c: move locking operations to their own struct

[Daniel Vetter]

On Thu, Aug 25, 2016 at 11:07:01PM +0200, Peter Rosin wrote:
> This makes it trivial to constify them, so do that.
> 
> Signed-off-by: Peter Rosin 

Acked-by: Daniel Vetter 

Feel free to merge through i2c tree.
-Daniel

> ---
>  drivers/gpu/drm/drm_dp_helper.c | 10 +++---
>  drivers/i2c/i2c-core.c  | 13 -
>  drivers/i2c/i2c-mux.c   | 25 -
>  include/linux/i2c.h | 25 ++---
>  4 files changed, 49 insertions(+), 24 deletions(-)
> 
> Changes since v1:
> 
> - Also fix the user in drivers/gpu (only compile-tested, but
>   it's simple enough...)
> 
> This takes care of the 0-day splat reported in:
> http://marc.info/?l=linux-i2c=147215193023544=2
> 
> Cheers,
> Peter
> 
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index eae5ef963cb7..2bd064493ae7 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -790,6 +790,12 @@ static void unlock_bus(struct i2c_adapter *i2c, unsigned 
> int flags)
>   mutex_unlock(_to_aux(i2c)->hw_mutex);
>  }
>  
> +static const struct i2c_lock_operations drm_dp_i2c_lock_ops = {
> + .lock_bus = lock_bus,
> + .trylock_bus = trylock_bus,
> + .unlock_bus = unlock_bus,
> +};
> +
>  /**
>   * drm_dp_aux_init() - minimally initialise an aux channel
>   * @aux: DisplayPort AUX channel
> @@ -807,9 +813,7 @@ void drm_dp_aux_init(struct drm_dp_aux *aux)
>   aux->ddc.algo_data = aux;
>   aux->ddc.retries = 3;
>  
> - aux->ddc.lock_bus = lock_bus;
> - aux->ddc.trylock_bus = trylock_bus;
> - aux->ddc.unlock_bus = unlock_bus;
> + aux->ddc.lock_ops = _dp_i2c_lock_ops;
>  }
>  EXPORT_SYMBOL(drm_dp_aux_init);
>  
> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> index 56e50ca905ba..0bdda24a10b2 100644
> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -1691,6 +1691,12 @@ static int __process_new_adapter(struct device_driver 
> *d, void *data)
>   return i2c_do_add_adapter(to_i2c_driver(d), data);
>  }
>  
> +static const struct i2c_lock_operations i2c_adapter_lock_ops = {
> + .lock_bus =i2c_adapter_lock_bus,
> + .trylock_bus = i2c_adapter_trylock_bus,
> + .unlock_bus =  i2c_adapter_unlock_bus,
> +};
> +
>  static int i2c_register_adapter(struct i2c_adapter *adap)
>  {
>   int res = -EINVAL;
> @@ -1710,11 +1716,8 @@ static int i2c_register_adapter(struct i2c_adapter 
> *adap)
>   goto out_list;
>   }
>  
> - if (!adap->lock_bus) {
> - adap->lock_bus = i2c_adapter_lock_bus;
> - adap->trylock_bus = i2c_adapter_trylock_bus;
> - adap->unlock_bus = i2c_adapter_unlock_bus;
> - }
> + if (!adap->lock_ops)
> + adap->lock_ops = _adapter_lock_ops;
>  
>   rt_mutex_init(>bus_lock);
>   rt_mutex_init(>mux_lock);
> diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
> index 764f195795e4..14741ff31041 100644
> --- a/drivers/i2c/i2c-mux.c
> +++ b/drivers/i2c/i2c-mux.c
> @@ -263,6 +263,18 @@ struct i2c_mux_core *i2c_mux_alloc(struct i2c_adapter 
> *parent,
>  }
>  EXPORT_SYMBOL_GPL(i2c_mux_alloc);
>  
> +static const struct i2c_lock_operations i2c_mux_lock_ops = {
> + .lock_bus =i2c_mux_lock_bus,
> + .trylock_bus = i2c_mux_trylock_bus,
> + .unlock_bus =  i2c_mux_unlock_bus,
> +};
> +
> +static const struct i2c_lock_operations i2c_parent_lock_ops = {
> + .lock_bus =i2c_parent_lock_bus,
> + .trylock_bus = i2c_parent_trylock_bus,
> + .unlock_bus =  i2c_parent_unlock_bus,
> +};
> +
>  int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
>   u32 force_nr, u32 chan_id,
>   unsigned int class)
> @@ -312,15 +324,10 @@ int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
>   priv->adap.retries = parent->retries;
>   priv->adap.timeout = parent->timeout;
>   priv->adap.quirks = parent->quirks;
> - if (muxc->mux_locked) {
> - priv->adap.lock_bus = i2c_mux_lock_bus;
> - priv->adap.trylock_bus = i2c_mux_trylock_bus;
> - priv->adap.unlock_bus = i2c_mux_unlock_bus;
> - } else {
> - priv->adap.lock_bus = i2c_parent_lock_bus;
> - priv->adap.trylock_bus = i2c_parent_trylock_bus;
> - priv->adap.unlock_bus = i2c_parent_unlock_bus;
> - }
> + if (muxc->mux_locked)
> + priv->adap.lock_ops = _mux_lock_ops;
> + else
> + priv->adap.lock_ops = _parent_lock_ops;
>  
>   /* Sanity check on class */
>   if (i2c_mux_parent_classes(parent) & class)
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index c1f60a345db7..616f67635734 100644
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -427,6 +427,20 @@ struct i2c_algorithm {
>  };
>  
>  /**
> + * struct i2c_lock_operations - represent I2C locking operations
> + * @lock_bus: Get exclusive access to an I2C bus segment
> + * @trylock_bus: 

[PATCH v2] i2c: move locking operations to their own struct

[Peter Rosin]

This makes it trivial to constify them, so do that.

Signed-off-by: Peter Rosin 
---
 drivers/gpu/drm/drm_dp_helper.c | 10 +++---
 drivers/i2c/i2c-core.c  | 13 -
 drivers/i2c/i2c-mux.c   | 25 -
 include/linux/i2c.h | 25 ++---
 4 files changed, 49 insertions(+), 24 deletions(-)

Changes since v1:

- Also fix the user in drivers/gpu (only compile-tested, but
  it's simple enough...)

This takes care of the 0-day splat reported in:
http://marc.info/?l=linux-i2c=147215193023544=2

Cheers,
Peter

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index eae5ef963cb7..2bd064493ae7 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -790,6 +790,12 @@ static void unlock_bus(struct i2c_adapter *i2c, unsigned 
int flags)
mutex_unlock(_to_aux(i2c)->hw_mutex);
 }

+static const struct i2c_lock_operations drm_dp_i2c_lock_ops = {
+   .lock_bus = lock_bus,
+   .trylock_bus = trylock_bus,
+   .unlock_bus = unlock_bus,
+};
+
 /**
  * drm_dp_aux_init() - minimally initialise an aux channel
  * @aux: DisplayPort AUX channel
@@ -807,9 +813,7 @@ void drm_dp_aux_init(struct drm_dp_aux *aux)
aux->ddc.algo_data = aux;
aux->ddc.retries = 3;

-   aux->ddc.lock_bus = lock_bus;
-   aux->ddc.trylock_bus = trylock_bus;
-   aux->ddc.unlock_bus = unlock_bus;
+   aux->ddc.lock_ops = _dp_i2c_lock_ops;
 }
 EXPORT_SYMBOL(drm_dp_aux_init);

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 56e50ca905ba..0bdda24a10b2 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -1691,6 +1691,12 @@ static int __process_new_adapter(struct device_driver 
*d, void *data)
return i2c_do_add_adapter(to_i2c_driver(d), data);
 }

+static const struct i2c_lock_operations i2c_adapter_lock_ops = {
+   .lock_bus =i2c_adapter_lock_bus,
+   .trylock_bus = i2c_adapter_trylock_bus,
+   .unlock_bus =  i2c_adapter_unlock_bus,
+};
+
 static int i2c_register_adapter(struct i2c_adapter *adap)
 {
int res = -EINVAL;
@@ -1710,11 +1716,8 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
goto out_list;
}

-   if (!adap->lock_bus) {
-   adap->lock_bus = i2c_adapter_lock_bus;
-   adap->trylock_bus = i2c_adapter_trylock_bus;
-   adap->unlock_bus = i2c_adapter_unlock_bus;
-   }
+   if (!adap->lock_ops)
+   adap->lock_ops = _adapter_lock_ops;

rt_mutex_init(>bus_lock);
rt_mutex_init(>mux_lock);
diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
index 764f195795e4..14741ff31041 100644
--- a/drivers/i2c/i2c-mux.c
+++ b/drivers/i2c/i2c-mux.c
@@ -263,6 +263,18 @@ struct i2c_mux_core *i2c_mux_alloc(struct i2c_adapter 
*parent,
 }
 EXPORT_SYMBOL_GPL(i2c_mux_alloc);

+static const struct i2c_lock_operations i2c_mux_lock_ops = {
+   .lock_bus =i2c_mux_lock_bus,
+   .trylock_bus = i2c_mux_trylock_bus,
+   .unlock_bus =  i2c_mux_unlock_bus,
+};
+
+static const struct i2c_lock_operations i2c_parent_lock_ops = {
+   .lock_bus =i2c_parent_lock_bus,
+   .trylock_bus = i2c_parent_trylock_bus,
+   .unlock_bus =  i2c_parent_unlock_bus,
+};
+
 int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
u32 force_nr, u32 chan_id,
unsigned int class)
@@ -312,15 +324,10 @@ int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
priv->adap.retries = parent->retries;
priv->adap.timeout = parent->timeout;
priv->adap.quirks = parent->quirks;
-   if (muxc->mux_locked) {
-   priv->adap.lock_bus = i2c_mux_lock_bus;
-   priv->adap.trylock_bus = i2c_mux_trylock_bus;
-   priv->adap.unlock_bus = i2c_mux_unlock_bus;
-   } else {
-   priv->adap.lock_bus = i2c_parent_lock_bus;
-   priv->adap.trylock_bus = i2c_parent_trylock_bus;
-   priv->adap.unlock_bus = i2c_parent_unlock_bus;
-   }
+   if (muxc->mux_locked)
+   priv->adap.lock_ops = _mux_lock_ops;
+   else
+   priv->adap.lock_ops = _parent_lock_ops;

/* Sanity check on class */
if (i2c_mux_parent_classes(parent) & class)
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index c1f60a345db7..616f67635734 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -427,6 +427,20 @@ struct i2c_algorithm {
 };

 /**
+ * struct i2c_lock_operations - represent I2C locking operations
+ * @lock_bus: Get exclusive access to an I2C bus segment
+ * @trylock_bus: Try to get exclusive access to an I2C bus segment
+ * @unlock_bus: Release exclusive access to an I2C bus segment
+ *
+ * The main operations are wrapped by i2c_lock_bus and i2c_unlock_bus.
+ */
+struct i2c_lock_operations {
+   void (*lock_bus)(struct i2c_adapter *, unsigned int flags);
+   int