[linux-2.6-block.git] / include / drm / drm_modeset_lock.h

/*
 * Copyright (C) 2014 Red Hat
 * Author: Rob Clark <robdclark@gmail.com>
 *
 * 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, sublicense,
 * 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 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 NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) 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 DRM_MODESET_LOCK_H_
#define DRM_MODESET_LOCK_H_

#include <linux/ww_mutex.h>

struct drm_modeset_lock;

/**
 * struct drm_modeset_acquire_ctx - locking context (see ww_acquire_ctx)
 * @ww_ctx: base acquire ctx
 * @contended: used internally for -EDEADLK handling
 * @locked: list of held locks
 * @trylock_only: trylock mode used in atomic contexts/panic notifiers
 * @interruptible: whether interruptible locking should be used.
 *
 * Each thread competing for a set of locks must use one acquire
 * ctx.  And if any lock fxn returns -EDEADLK, it must backoff and
 * retry.
 */
struct drm_modeset_acquire_ctx {

	struct ww_acquire_ctx ww_ctx;

	/*
	 * Contended lock: if a lock is contended you should only call
	 * drm_modeset_backoff() which drops locks and slow-locks the
	 * contended lock.
	 */
	struct drm_modeset_lock *contended;

	/*
	 * list of held locks (drm_modeset_lock)
	 */
	struct list_head locked;

	/*
	 * Trylock mode, use only for panic handlers!
	 */
	bool trylock_only;

	/* Perform interruptible waits on this context. */
	bool interruptible;
};

/**
 * struct drm_modeset_lock - used for locking modeset resources.
 * @mutex: resource locking
 * @head: used to hold it's place on &drm_atomi_state.locked list when
 *    part of an atomic update
 *
 * Used for locking CRTCs and other modeset resources.
 */
struct drm_modeset_lock {
	/*
	 * modeset lock
	 */
	struct ww_mutex mutex;

	/*
	 * Resources that are locked as part of an atomic update are added
	 * to a list (so we know what to unlock at the end).
	 */
	struct list_head head;
};

#define DRM_MODESET_ACQUIRE_INTERRUPTIBLE BIT(0)

void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
		uint32_t flags);
void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx);
void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx);
int drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx);

void drm_modeset_lock_init(struct drm_modeset_lock *lock);

/**
 * drm_modeset_lock_fini - cleanup lock
 * @lock: lock to cleanup
 */
static inline void drm_modeset_lock_fini(struct drm_modeset_lock *lock)
{
	WARN_ON(!list_empty(&lock->head));
}

/**
 * drm_modeset_is_locked - equivalent to mutex_is_locked()
 * @lock: lock to check
 */
static inline bool drm_modeset_is_locked(struct drm_modeset_lock *lock)
{
	return ww_mutex_is_locked(&lock->mutex);
}

int drm_modeset_lock(struct drm_modeset_lock *lock,
		struct drm_modeset_acquire_ctx *ctx);
int __must_check drm_modeset_lock_single_interruptible(struct drm_modeset_lock *lock);
void drm_modeset_unlock(struct drm_modeset_lock *lock);

struct drm_device;
struct drm_crtc;
struct drm_plane;

void drm_modeset_lock_all(struct drm_device *dev);
void drm_modeset_unlock_all(struct drm_device *dev);
void drm_warn_on_modeset_not_all_locked(struct drm_device *dev);

int drm_modeset_lock_all_ctx(struct drm_device *dev,
			     struct drm_modeset_acquire_ctx *ctx);

/**
 * DRM_MODESET_LOCK_ALL_BEGIN - Helper to acquire modeset locks
 * @dev: drm device
 * @ctx: local modeset acquire context, will be dereferenced
 * @flags: DRM_MODESET_ACQUIRE_* flags to pass to drm_modeset_acquire_init()
 * @ret: local ret/err/etc variable to track error status
 *
 * Use these macros to simplify grabbing all modeset locks using a local
 * context. This has the advantage of reducing boilerplate, but also properly
 * checking return values where appropriate.
 *
 * Any code run between BEGIN and END will be holding the modeset locks.
 *
 * This must be paired with DRM_MODESET_LOCK_ALL_END(). We will jump back and
 * forth between the labels on deadlock and error conditions.
 *
 * Drivers can acquire additional modeset locks. If any lock acquisition
 * fails, the control flow needs to jump to DRM_MODESET_LOCK_ALL_END() with
 * the @ret parameter containing the return value of drm_modeset_lock().
 *
 * Returns:
 * The only possible value of ret immediately after DRM_MODESET_LOCK_ALL_BEGIN()
 * is 0, so no error checking is necessary
 */
#define DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, flags, ret)		\
	drm_modeset_acquire_init(&ctx, flags);				\
modeset_lock_retry:							\
	ret = drm_modeset_lock_all_ctx(dev, &ctx);			\
	if (ret)							\
		goto modeset_lock_fail;

/**
 * DRM_MODESET_LOCK_ALL_END - Helper to release and cleanup modeset locks
 * @ctx: local modeset acquire context, will be dereferenced
 * @ret: local ret/err/etc variable to track error status
 *
 * The other side of DRM_MODESET_LOCK_ALL_BEGIN(). It will bounce back to BEGIN
 * if ret is -EDEADLK.
 *
 * It's important that you use the same ret variable for begin and end so
 * deadlock conditions are properly handled.
 *
 * Returns:
 * ret will be untouched unless it is -EDEADLK on entry. That means that if you
 * successfully acquire the locks, ret will be whatever your code sets it to. If
 * there is a deadlock or other failure with acquire or backoff, ret will be set
 * to that failure. In both of these cases the code between BEGIN/END will not
 * be run, so the failure will reflect the inability to grab the locks.
 */
#define DRM_MODESET_LOCK_ALL_END(ctx, ret)				\
modeset_lock_fail:							\
	if (ret == -EDEADLK) {						\
		ret = drm_modeset_backoff(&ctx);			\
		if (!ret)						\
			goto modeset_lock_retry;			\
	}								\
	drm_modeset_drop_locks(&ctx);					\
	drm_modeset_acquire_fini(&ctx);

#endif /* DRM_MODESET_LOCK_H_ */
Commit	Line	Data
51fd371b RC	1	/*
	2	* Copyright (C) 2014 Red Hat
	3	* Author: Rob Clark <robdclark@gmail.com>
	4	*
	5	* Permission is hereby granted, free of charge, to any person obtaining a
	6	* copy of this software and associated documentation files (the "Software"),
	7	* to deal in the Software without restriction, including without limitation
	8	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	9	* and/or sell copies of the Software, and to permit persons to whom the
	10	* Software is furnished to do so, subject to the following conditions:
	11	*
	12	* The above copyright notice and this permission notice shall be included in
	13	* all copies or substantial portions of the Software.
	14	*
	15	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	16	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	17	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	18	* THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
	19	* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
	20	* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
	21	* OTHER DEALINGS IN THE SOFTWARE.
	22	*/
	23
	24	#ifndef DRM_MODESET_LOCK_H_
	25	#define DRM_MODESET_LOCK_H_
	26
	27	#include <linux/ww_mutex.h>
	28
	29	struct drm_modeset_lock;
	30
	31	/**
f3a80881	32	* struct drm_modeset_acquire_ctx - locking context (see ww_acquire_ctx)
51fd371b RC	33	* @ww_ctx: base acquire ctx
	34	* @contended: used internally for -EDEADLK handling
	35	* @locked: list of held locks
b7a1aafd	36	* @trylock_only: trylock mode used in atomic contexts/panic notifiers
6f8bcc74	37	* @interruptible: whether interruptible locking should be used.
51fd371b RC	38	*
	39	* Each thread competing for a set of locks must use one acquire
	40	* ctx. And if any lock fxn returns -EDEADLK, it must backoff and
	41	* retry.
	42	*/
	43	struct drm_modeset_acquire_ctx {
	44
	45	struct ww_acquire_ctx ww_ctx;
	46
fe8660ac	47	/*
51fd371b RC	48	* Contended lock: if a lock is contended you should only call
	49	* drm_modeset_backoff() which drops locks and slow-locks the
	50	* contended lock.
	51	*/
	52	struct drm_modeset_lock *contended;
	53
fe8660ac	54	/*
51fd371b RC	55	* list of held locks (drm_modeset_lock)
	56	*/
	57	struct list_head locked;
cb597bb3	58
fe8660ac	59	/*
cb597bb3 DV	60	* Trylock mode, use only for panic handlers!
	61	*/
	62	bool trylock_only;
6f8bcc74 ML	63
	64	/* Perform interruptible waits on this context. */
	65	bool interruptible;
51fd371b RC	66	};
	67
	68	/**
f3a80881	69	* struct drm_modeset_lock - used for locking modeset resources.
51fd371b	70	* @mutex: resource locking
d574528a	71	* @head: used to hold it's place on &drm_atomi_state.locked list when
51fd371b RC	72	* part of an atomic update
	73	*
	74	* Used for locking CRTCs and other modeset resources.
	75	*/
	76	struct drm_modeset_lock {
fe8660ac	77	/*
51fd371b RC	78	* modeset lock
	79	*/
	80	struct ww_mutex mutex;
	81
fe8660ac	82	/*
51fd371b RC	83	* Resources that are locked as part of an atomic update are added
	84	* to a list (so we know what to unlock at the end).
	85	*/
	86	struct list_head head;
	87	};
	88
6f8bcc74 ML	89	#define DRM_MODESET_ACQUIRE_INTERRUPTIBLE BIT(0)
6f8bcc74 ML	90
51fd371b RC	91	void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
	92	uint32_t flags);
	93	void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx);
	94	void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx);
6f8bcc74	95	int drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx);
51fd371b	96
35cf0350	97	void drm_modeset_lock_init(struct drm_modeset_lock *lock);
51fd371b RC	98
	99	/**
	100	* drm_modeset_lock_fini - cleanup lock
	101	* @lock: lock to cleanup
	102	*/
	103	static inline void drm_modeset_lock_fini(struct drm_modeset_lock *lock)
	104	{
	105	WARN_ON(!list_empty(&lock->head));
	106	}
	107
	108	/**
	109	* drm_modeset_is_locked - equivalent to mutex_is_locked()
	110	* @lock: lock to check
	111	*/
	112	static inline bool drm_modeset_is_locked(struct drm_modeset_lock *lock)
	113	{
	114	return ww_mutex_is_locked(&lock->mutex);
	115	}
	116
	117	int drm_modeset_lock(struct drm_modeset_lock *lock,
	118	struct drm_modeset_acquire_ctx *ctx);
6f8bcc74	119	int __must_check drm_modeset_lock_single_interruptible(struct drm_modeset_lock *lock);
51fd371b RC	120	void drm_modeset_unlock(struct drm_modeset_lock *lock);
	121
	122	struct drm_device;
d059f652	123	struct drm_crtc;
4d02e2de	124	struct drm_plane;
a6a8bb84 DV	125
	126	void drm_modeset_lock_all(struct drm_device *dev);
	127	void drm_modeset_unlock_all(struct drm_device *dev);
	128	void drm_warn_on_modeset_not_all_locked(struct drm_device *dev);
	129
06eaae46 TR	130	int drm_modeset_lock_all_ctx(struct drm_device *dev,
06eaae46 TR	131	struct drm_modeset_acquire_ctx *ctx);
51fd371b	132
b7ea04d2 SP	133	/**
	134	* DRM_MODESET_LOCK_ALL_BEGIN - Helper to acquire modeset locks
	135	* @dev: drm device
	136	* @ctx: local modeset acquire context, will be dereferenced
	137	* @flags: DRM_MODESET_ACQUIRE_* flags to pass to drm_modeset_acquire_init()
	138	* @ret: local ret/err/etc variable to track error status
	139	*
	140	* Use these macros to simplify grabbing all modeset locks using a local
	141	* context. This has the advantage of reducing boilerplate, but also properly
	142	* checking return values where appropriate.
	143	*
	144	* Any code run between BEGIN and END will be holding the modeset locks.
	145	*
	146	* This must be paired with DRM_MODESET_LOCK_ALL_END(). We will jump back and
	147	* forth between the labels on deadlock and error conditions.
	148	*
	149	* Drivers can acquire additional modeset locks. If any lock acquisition
	150	* fails, the control flow needs to jump to DRM_MODESET_LOCK_ALL_END() with
	151	* the @ret parameter containing the return value of drm_modeset_lock().
	152	*
	153	* Returns:
	154	* The only possible value of ret immediately after DRM_MODESET_LOCK_ALL_BEGIN()
	155	* is 0, so no error checking is necessary
	156	*/
	157	#define DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, flags, ret) \
	158	drm_modeset_acquire_init(&ctx, flags); \
	159	modeset_lock_retry: \
	160	ret = drm_modeset_lock_all_ctx(dev, &ctx); \
	161	if (ret) \
	162	goto modeset_lock_fail;
	163
	164	/**
	165	* DRM_MODESET_LOCK_ALL_END - Helper to release and cleanup modeset locks
	166	* @ctx: local modeset acquire context, will be dereferenced
	167	* @ret: local ret/err/etc variable to track error status
	168	*
	169	* The other side of DRM_MODESET_LOCK_ALL_BEGIN(). It will bounce back to BEGIN
	170	* if ret is -EDEADLK.
	171	*
	172	* It's important that you use the same ret variable for begin and end so
	173	* deadlock conditions are properly handled.
	174	*
	175	* Returns:
	176	* ret will be untouched unless it is -EDEADLK on entry. That means that if you
	177	* successfully acquire the locks, ret will be whatever your code sets it to. If
	178	* there is a deadlock or other failure with acquire or backoff, ret will be set
	179	* to that failure. In both of these cases the code between BEGIN/END will not
	180	* be run, so the failure will reflect the inability to grab the locks.
	181	*/
	182	#define DRM_MODESET_LOCK_ALL_END(ctx, ret) \
	183	modeset_lock_fail: \
	184	if (ret == -EDEADLK) { \
	185	ret = drm_modeset_backoff(&ctx); \
	186	if (!ret) \
	187	goto modeset_lock_retry; \
	188	} \
	189	drm_modeset_drop_locks(&ctx); \
	190	drm_modeset_acquire_fini(&ctx);
	191
51fd371b	192	#endif /* DRM_MODESET_LOCK_H_ */