include/linux/dma-resv.h - linux - Git at Google

 /*
  * Header file for reservations for dma-buf and ttm
  *
  * Copyright(C) 2011 Linaro Limited. All rights reserved.
  * Copyright (C) 2012-2013 Canonical Ltd
  * Copyright (C) 2012 Texas Instruments
  *
  * Authors:
  * Rob Clark <robdclark@gmail.com>
  * Maarten Lankhorst <maarten.lankhorst@canonical.com>
  * Thomas Hellstrom <thellstrom-at-vmware-dot-com>
  *
  * Based on bo.c which bears the following copyright notice,
  * but is dual licensed:
  *
  * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
  * All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the
  * "Software"), to deal in the Software without restriction, including
  * without limitation the rights to use, copy, modify, merge, publish,
  * distribute, sub license, and/or sell copies of the Software, and to
  * permit persons to whom the Software is furnished to do so, subject to
  * the following conditions:
  *
  * The above copyright notice and this permission notice (including the
  * next paragraph) shall be included in all copies or substantial portions
  * of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
 #ifndef _LINUX_RESERVATION_H
 #define _LINUX_RESERVATION_H

 #include <linux/ww_mutex.h>
 #include <linux/dma-fence.h>
 #include <linux/slab.h>
 #include <linux/seqlock.h>
 #include <linux/rcupdate.h>

 extern struct ww_class reservation_ww_class;

 /**
  * struct dma_resv_list - a list of shared fences
  * @rcu: for internal use
  * @shared_count: table of shared fences
  * @shared_max: for growing shared fence table
  * @shared: shared fence table
  */
 struct dma_resv_list {
 	struct rcu_head rcu;
 	u32 shared_count, shared_max;
 	struct dma_fence __rcu *shared[];
 };

 /**
  * struct dma_resv - a reservation object manages fences for a buffer
  * @lock: update side lock
  * @seq: sequence count for managing RCU read-side synchronization
  * @fence_excl: the exclusive fence, if there is one currently
  * @fence: list of current shared fences
  */
 struct dma_resv {
 	struct ww_mutex lock;
 	seqcount_ww_mutex_t seq;

 	struct dma_fence __rcu *fence_excl;
 	struct dma_resv_list __rcu *fence;
 };

 #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
 #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)

 /**
  * dma_resv_get_list - get the reservation object's
  * shared fence list, with update-side lock held
  * @obj: the reservation object
  *
  * Returns the shared fence list.  Does NOT take references to
  * the fence.  The obj->lock must be held.
  */
 static inline struct dma_resv_list *dma_resv_get_list(struct dma_resv *obj)
 {
 	return rcu_dereference_protected(obj->fence,
 					 dma_resv_held(obj));
 }

 /**
  * dma_resv_lock - lock the reservation object
  * @obj: the reservation object
  * @ctx: the locking context
  *
  * Locks the reservation object for exclusive access and modification. Note,
  * that the lock is only against other writers, readers will run concurrently
  * with a writer under RCU. The seqlock is used to notify readers if they
  * overlap with a writer.
  *
  * As the reservation object may be locked by multiple parties in an
  * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
  * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
  * object may be locked by itself by passing NULL as @ctx.
  */
 static inline int dma_resv_lock(struct dma_resv *obj,
 				struct ww_acquire_ctx *ctx)
 {
 	return ww_mutex_lock(&obj->lock, ctx);
 }

 /**
  * dma_resv_lock_interruptible - lock the reservation object
  * @obj: the reservation object
  * @ctx: the locking context
  *
  * Locks the reservation object interruptible for exclusive access and
  * modification. Note, that the lock is only against other writers, readers
  * will run concurrently with a writer under RCU. The seqlock is used to
  * notify readers if they overlap with a writer.
  *
  * As the reservation object may be locked by multiple parties in an
  * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
  * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
  * object may be locked by itself by passing NULL as @ctx.
  */
 static inline int dma_resv_lock_interruptible(struct dma_resv *obj,
 					      struct ww_acquire_ctx *ctx)
 {
 	return ww_mutex_lock_interruptible(&obj->lock, ctx);
 }

 /**
  * dma_resv_lock_slow - slowpath lock the reservation object
  * @obj: the reservation object
  * @ctx: the locking context
  *
  * Acquires the reservation object after a die case. This function
  * will sleep until the lock becomes available. See dma_resv_lock() as
  * well.
  */
 static inline void dma_resv_lock_slow(struct dma_resv *obj,
 				      struct ww_acquire_ctx *ctx)
 {
 	ww_mutex_lock_slow(&obj->lock, ctx);
 }

 /**
  * dma_resv_lock_slow_interruptible - slowpath lock the reservation
  * object, interruptible
  * @obj: the reservation object
  * @ctx: the locking context
  *
  * Acquires the reservation object interruptible after a die case. This function
  * will sleep until the lock becomes available. See
  * dma_resv_lock_interruptible() as well.
  */
 static inline int dma_resv_lock_slow_interruptible(struct dma_resv *obj,
 						   struct ww_acquire_ctx *ctx)
 {
 	return ww_mutex_lock_slow_interruptible(&obj->lock, ctx);
 }

 /**
  * dma_resv_trylock - trylock the reservation object
  * @obj: the reservation object
  *
  * Tries to lock the reservation object for exclusive access and modification.
  * Note, that the lock is only against other writers, readers will run
  * concurrently with a writer under RCU. The seqlock is used to notify readers
  * if they overlap with a writer.
  *
  * Also note that since no context is provided, no deadlock protection is
  * possible.
  *
  * Returns true if the lock was acquired, false otherwise.
  */
 static inline bool __must_check dma_resv_trylock(struct dma_resv *obj)
 {
 	return ww_mutex_trylock(&obj->lock);
 }

 /**
  * dma_resv_is_locked - is the reservation object locked
  * @obj: the reservation object
  *
  * Returns true if the mutex is locked, false if unlocked.
  */
 static inline bool dma_resv_is_locked(struct dma_resv *obj)
 {
 	return ww_mutex_is_locked(&obj->lock);
 }

 /**
  * dma_resv_locking_ctx - returns the context used to lock the object
  * @obj: the reservation object
  *
  * Returns the context used to lock a reservation object or NULL if no context
  * was used or the object is not locked at all.
  */
 static inline struct ww_acquire_ctx *dma_resv_locking_ctx(struct dma_resv *obj)
 {
 	return READ_ONCE(obj->lock.ctx);
 }

 /**
  * dma_resv_unlock - unlock the reservation object
  * @obj: the reservation object
  *
  * Unlocks the reservation object following exclusive access.
  */
 static inline void dma_resv_unlock(struct dma_resv *obj)
 {
 #ifdef CONFIG_DEBUG_MUTEXES
 	/* Test shared fence slot reservation */
 	if (rcu_access_pointer(obj->fence)) {
 		struct dma_resv_list *fence = dma_resv_get_list(obj);

 		fence->shared_max = fence->shared_count;
 	}
 #endif
 	ww_mutex_unlock(&obj->lock);
 }

 /**
  * dma_resv_get_excl - get the reservation object's
  * exclusive fence, with update-side lock held
  * @obj: the reservation object
  *
  * Returns the exclusive fence (if any).  Does NOT take a
  * reference. Writers must hold obj->lock, readers may only
  * hold a RCU read side lock.
  *
  * RETURNS
  * The exclusive fence or NULL
  */
 static inline struct dma_fence *
 dma_resv_get_excl(struct dma_resv *obj)
 {
 	return rcu_dereference_protected(obj->fence_excl,
 					 dma_resv_held(obj));
 }

 /**
  * dma_resv_get_excl_rcu - get the reservation object's
  * exclusive fence, without lock held.
  * @obj: the reservation object
  *
  * If there is an exclusive fence, this atomically increments it's
  * reference count and returns it.
  *
  * RETURNS
  * The exclusive fence or NULL if none
  */
 static inline struct dma_fence *
 dma_resv_get_excl_rcu(struct dma_resv *obj)
 {
 	struct dma_fence *fence;

 	if (!rcu_access_pointer(obj->fence_excl))
 		return NULL;

 	rcu_read_lock();
 	fence = dma_fence_get_rcu_safe(&obj->fence_excl);
 	rcu_read_unlock();

 	return fence;
 }

 void dma_resv_init(struct dma_resv *obj);
 void dma_resv_fini(struct dma_resv *obj);
 int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences);
 void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);

 void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);

 int dma_resv_get_fences_rcu(struct dma_resv *obj,
 			    struct dma_fence **pfence_excl,
 			    unsigned *pshared_count,
 			    struct dma_fence ***pshared);

 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);

 long dma_resv_wait_timeout_rcu(struct dma_resv *obj, bool wait_all, bool intr,
 			       unsigned long timeout);

 bool dma_resv_test_signaled_rcu(struct dma_resv *obj, bool test_all);

 #endif /* _LINUX_RESERVATION_H */
	/*
	* Header file for reservations for dma-buf and ttm
	*
	* Copyright(C) 2011 Linaro Limited. All rights reserved.
	* Copyright (C) 2012-2013 Canonical Ltd
	* Copyright (C) 2012 Texas Instruments
	*
	* Authors:
	* Rob Clark <robdclark@gmail.com>
	* Maarten Lankhorst <maarten.lankhorst@canonical.com>
	* Thomas Hellstrom <thellstrom-at-vmware-dot-com>
	*
	* Based on bo.c which bears the following copyright notice,
	* but is dual licensed:
	*
	* Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
	* All Rights Reserved.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the
	* "Software"), to deal in the Software without restriction, including
	* without limitation the rights to use, copy, modify, merge, publish,
	* distribute, sub license, and/or sell copies of the Software, and to
	* permit persons to whom the Software is furnished to do so, subject to
	* the following conditions:
	*
	* The above copyright notice and this permission notice (including the
	* next paragraph) shall be included in all copies or substantial portions
	* of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
	* THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
	* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
	* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
	* USE OR OTHER DEALINGS IN THE SOFTWARE.
	*/
	#ifndef _LINUX_RESERVATION_H
	#define _LINUX_RESERVATION_H

	#include <linux/ww_mutex.h>
	#include <linux/dma-fence.h>
	#include <linux/slab.h>
	#include <linux/seqlock.h>
	#include <linux/rcupdate.h>

	extern struct ww_class reservation_ww_class;

	/**
	* struct dma_resv_list - a list of shared fences
	* @rcu: for internal use
	* @shared_count: table of shared fences
	* @shared_max: for growing shared fence table
	* @shared: shared fence table
	*/
	struct dma_resv_list {
	struct rcu_head rcu;
	u32 shared_count, shared_max;
	struct dma_fence __rcu *shared[];
	};

	/**
	* struct dma_resv - a reservation object manages fences for a buffer
	* @lock: update side lock
	* @seq: sequence count for managing RCU read-side synchronization
	* @fence_excl: the exclusive fence, if there is one currently
	* @fence: list of current shared fences
	*/
	struct dma_resv {
	struct ww_mutex lock;
	seqcount_ww_mutex_t seq;

	struct dma_fence __rcu *fence_excl;
	struct dma_resv_list __rcu *fence;
	};

	#define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
	#define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)

	/**
	* dma_resv_get_list - get the reservation object's
	* shared fence list, with update-side lock held
	* @obj: the reservation object
	*
	* Returns the shared fence list. Does NOT take references to
	* the fence. The obj->lock must be held.
	*/
	static inline struct dma_resv_list dma_resv_get_list(struct dma_resv obj)
	{
	return rcu_dereference_protected(obj->fence,
	dma_resv_held(obj));
	}

	/**
	* dma_resv_lock - lock the reservation object
	* @obj: the reservation object
	* @ctx: the locking context
	*
	* Locks the reservation object for exclusive access and modification. Note,
	* that the lock is only against other writers, readers will run concurrently
	* with a writer under RCU. The seqlock is used to notify readers if they
	* overlap with a writer.
	*
	* As the reservation object may be locked by multiple parties in an
	* undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
	* is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
	* object may be locked by itself by passing NULL as @ctx.
	*/
	static inline int dma_resv_lock(struct dma_resv *obj,
	struct ww_acquire_ctx *ctx)
	{
	return ww_mutex_lock(&obj->lock, ctx);
	}

	/**
	* dma_resv_lock_interruptible - lock the reservation object
	* @obj: the reservation object
	* @ctx: the locking context
	*
	* Locks the reservation object interruptible for exclusive access and
	* modification. Note, that the lock is only against other writers, readers
	* will run concurrently with a writer under RCU. The seqlock is used to
	* notify readers if they overlap with a writer.
	*
	* As the reservation object may be locked by multiple parties in an
	* undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
	* is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
	* object may be locked by itself by passing NULL as @ctx.
	*/
	static inline int dma_resv_lock_interruptible(struct dma_resv *obj,
	struct ww_acquire_ctx *ctx)
	{
	return ww_mutex_lock_interruptible(&obj->lock, ctx);
	}

	/**
	* dma_resv_lock_slow - slowpath lock the reservation object
	* @obj: the reservation object
	* @ctx: the locking context
	*
	* Acquires the reservation object after a die case. This function
	* will sleep until the lock becomes available. See dma_resv_lock() as
	* well.
	*/
	static inline void dma_resv_lock_slow(struct dma_resv *obj,
	struct ww_acquire_ctx *ctx)
	{
	ww_mutex_lock_slow(&obj->lock, ctx);
	}

	/**
	* dma_resv_lock_slow_interruptible - slowpath lock the reservation
	* object, interruptible
	* @obj: the reservation object
	* @ctx: the locking context
	*
	* Acquires the reservation object interruptible after a die case. This function
	* will sleep until the lock becomes available. See
	* dma_resv_lock_interruptible() as well.
	*/
	static inline int dma_resv_lock_slow_interruptible(struct dma_resv *obj,
	struct ww_acquire_ctx *ctx)
	{
	return ww_mutex_lock_slow_interruptible(&obj->lock, ctx);
	}

	/**
	* dma_resv_trylock - trylock the reservation object
	* @obj: the reservation object
	*
	* Tries to lock the reservation object for exclusive access and modification.
	* Note, that the lock is only against other writers, readers will run
	* concurrently with a writer under RCU. The seqlock is used to notify readers
	* if they overlap with a writer.
	*
	* Also note that since no context is provided, no deadlock protection is
	* possible.
	*
	* Returns true if the lock was acquired, false otherwise.
	*/
	static inline bool __must_check dma_resv_trylock(struct dma_resv *obj)
	{
	return ww_mutex_trylock(&obj->lock);
	}

	/**
	* dma_resv_is_locked - is the reservation object locked
	* @obj: the reservation object
	*
	* Returns true if the mutex is locked, false if unlocked.
	*/
	static inline bool dma_resv_is_locked(struct dma_resv *obj)
	{
	return ww_mutex_is_locked(&obj->lock);
	}

	/**
	* dma_resv_locking_ctx - returns the context used to lock the object
	* @obj: the reservation object
	*
	* Returns the context used to lock a reservation object or NULL if no context
	* was used or the object is not locked at all.
	*/
	static inline struct ww_acquire_ctx dma_resv_locking_ctx(struct dma_resv obj)
	{
	return READ_ONCE(obj->lock.ctx);
	}

	/**
	* dma_resv_unlock - unlock the reservation object
	* @obj: the reservation object
	*
	* Unlocks the reservation object following exclusive access.
	*/
	static inline void dma_resv_unlock(struct dma_resv *obj)
	{
	#ifdef CONFIG_DEBUG_MUTEXES
	/* Test shared fence slot reservation */
	if (rcu_access_pointer(obj->fence)) {
	struct dma_resv_list *fence = dma_resv_get_list(obj);

	fence->shared_max = fence->shared_count;
	}
	#endif
	ww_mutex_unlock(&obj->lock);
	}

	/**
	* dma_resv_get_excl - get the reservation object's
	* exclusive fence, with update-side lock held
	* @obj: the reservation object
	*
	* Returns the exclusive fence (if any). Does NOT take a
	* reference. Writers must hold obj->lock, readers may only
	* hold a RCU read side lock.
	*
	* RETURNS
	* The exclusive fence or NULL
	*/
	static inline struct dma_fence *
	dma_resv_get_excl(struct dma_resv *obj)
	{
	return rcu_dereference_protected(obj->fence_excl,
	dma_resv_held(obj));
	}

	/**
	* dma_resv_get_excl_rcu - get the reservation object's
	* exclusive fence, without lock held.
	* @obj: the reservation object
	*
	* If there is an exclusive fence, this atomically increments it's
	* reference count and returns it.
	*
	* RETURNS
	* The exclusive fence or NULL if none
	*/
	static inline struct dma_fence *
	dma_resv_get_excl_rcu(struct dma_resv *obj)
	{
	struct dma_fence *fence;

	if (!rcu_access_pointer(obj->fence_excl))
	return NULL;

	rcu_read_lock();
	fence = dma_fence_get_rcu_safe(&obj->fence_excl);
	rcu_read_unlock();

	return fence;
	}

	void dma_resv_init(struct dma_resv *obj);
	void dma_resv_fini(struct dma_resv *obj);
	int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences);
	void dma_resv_add_shared_fence(struct dma_resv obj, struct dma_fence fence);

	void dma_resv_add_excl_fence(struct dma_resv obj, struct dma_fence fence);

	int dma_resv_get_fences_rcu(struct dma_resv *obj,
	struct dma_fence **pfence_excl,
	unsigned *pshared_count,
	struct dma_fence ***pshared);

	int dma_resv_copy_fences(struct dma_resv dst, struct dma_resv src);

	long dma_resv_wait_timeout_rcu(struct dma_resv *obj, bool wait_all, bool intr,
	unsigned long timeout);

	bool dma_resv_test_signaled_rcu(struct dma_resv *obj, bool test_all);

	#endif /* _LINUX_RESERVATION_H */