include/drm/drm_modeset_lock.h

   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 /**
  32  * struct drm_modeset_acquire_ctx - locking context (see ww_acquire_ctx)
  33  * @ww_ctx: base acquire ctx
  34  * @contended: used internally for -EDEADLK handling
  35  * @locked: list of held locks
  36  * @trylock_only: trylock mode used in atomic contexts/panic notifiers
  37  * @interruptible: whether interruptible locking should be used.
  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
  47         /*
  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
  54         /*
  55          * list of held locks (drm_modeset_lock)
  56          */
  57         struct list_head locked;
  58
  59         /*
  60          * Trylock mode, use only for panic handlers!
  61          */
  62         bool trylock_only;
  63
  64         /* Perform interruptible waits on this context. */
  65         bool interruptible;
  66 };
  67
  68 /**
  69  * struct drm_modeset_lock - used for locking modeset resources.
  70  * @mutex: resource locking
  71  * @head: used to hold it's place on &drm_atomi_state.locked list when
  72  *    part of an atomic update
  73  *
  74  * Used for locking CRTCs and other modeset resources.
  75  */
  76 struct drm_modeset_lock {
  77         /*
  78          * modeset lock
  79          */
  80         struct ww_mutex mutex;
  81
  82         /*
  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
  89 #define DRM_MODESET_ACQUIRE_INTERRUPTIBLE BIT(0)
  90
  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);
  95 int drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx);
  96
  97 void drm_modeset_lock_init(struct drm_modeset_lock *lock);
  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);
 119 int __must_check drm_modeset_lock_single_interruptible(struct drm_modeset_lock *lock);
 120 void drm_modeset_unlock(struct drm_modeset_lock *lock);
 121
 122 struct drm_device;
 123 struct drm_crtc;
 124 struct drm_plane;
 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
 130 int drm_modeset_lock_all_ctx(struct drm_device *dev,
 131                              struct drm_modeset_acquire_ctx *ctx);
 132
 133 #endif /* DRM_MODESET_LOCK_H_ */