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1/*2 * Copyright (C) 2014 Red Hat3 * Author: Rob Clark <robdclark@gmail.com>4 *5 * Permission is hereby granted, free of charge, to any person obtaining a6 * copy of this software and associated documentation files (the "Software"),7 * to deal in the Software without restriction, including without limitation8 * the rights to use, copy, modify, merge, publish, distribute, sublicense,9 * and/or sell copies of the Software, and to permit persons to whom the10 * Software is furnished to do so, subject to the following conditions:11 *12 * The above copyright notice and this permission notice shall be included in13 * all copies or substantial portions of the Software.14 *15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL18 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR19 * 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 OR21 * OTHER DEALINGS IN THE SOFTWARE.22 */23 24#ifndef DRM_MODESET_LOCK_H_25#define DRM_MODESET_LOCK_H_26 27#include <linux/types.h> /* stackdepot.h is not self-contained */28#include <linux/stackdepot.h>29#include <linux/ww_mutex.h>30 31struct drm_modeset_lock;32 33/**34 * struct drm_modeset_acquire_ctx - locking context (see ww_acquire_ctx)35 * @ww_ctx: base acquire ctx36 * @contended: used internally for -EDEADLK handling37 * @stack_depot: used internally for contention debugging38 * @locked: list of held locks39 * @trylock_only: trylock mode used in atomic contexts/panic notifiers40 * @interruptible: whether interruptible locking should be used.41 *42 * Each thread competing for a set of locks must use one acquire43 * ctx. And if any lock fxn returns -EDEADLK, it must backoff and44 * retry.45 */46struct drm_modeset_acquire_ctx {47 48 struct ww_acquire_ctx ww_ctx;49 50 /*51 * Contended lock: if a lock is contended you should only call52 * drm_modeset_backoff() which drops locks and slow-locks the53 * contended lock.54 */55 struct drm_modeset_lock *contended;56 57 /*58 * Stack depot for debugging when a contended lock was not backed off59 * from.60 */61 depot_stack_handle_t stack_depot;62 63 /*64 * list of held locks (drm_modeset_lock)65 */66 struct list_head locked;67 68 /*69 * Trylock mode, use only for panic handlers!70 */71 bool trylock_only;72 73 /* Perform interruptible waits on this context. */74 bool interruptible;75};76 77/**78 * struct drm_modeset_lock - used for locking modeset resources.79 * @mutex: resource locking80 * @head: used to hold its place on &drm_atomi_state.locked list when81 * part of an atomic update82 *83 * Used for locking CRTCs and other modeset resources.84 */85struct drm_modeset_lock {86 /*87 * modeset lock88 */89 struct ww_mutex mutex;90 91 /*92 * Resources that are locked as part of an atomic update are added93 * to a list (so we know what to unlock at the end).94 */95 struct list_head head;96};97 98#define DRM_MODESET_ACQUIRE_INTERRUPTIBLE BIT(0)99 100void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,101 uint32_t flags);102void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx);103void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx);104int drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx);105 106void drm_modeset_lock_init(struct drm_modeset_lock *lock);107 108/**109 * drm_modeset_lock_fini - cleanup lock110 * @lock: lock to cleanup111 */112static inline void drm_modeset_lock_fini(struct drm_modeset_lock *lock)113{114 WARN_ON(!list_empty(&lock->head));115}116 117/**118 * drm_modeset_is_locked - equivalent to mutex_is_locked()119 * @lock: lock to check120 */121static inline bool drm_modeset_is_locked(struct drm_modeset_lock *lock)122{123 return ww_mutex_is_locked(&lock->mutex);124}125 126/**127 * drm_modeset_lock_assert_held - equivalent to lockdep_assert_held()128 * @lock: lock to check129 */130static inline void drm_modeset_lock_assert_held(struct drm_modeset_lock *lock)131{132 lockdep_assert_held(&lock->mutex.base);133}134 135int drm_modeset_lock(struct drm_modeset_lock *lock,136 struct drm_modeset_acquire_ctx *ctx);137int __must_check drm_modeset_lock_single_interruptible(struct drm_modeset_lock *lock);138void drm_modeset_unlock(struct drm_modeset_lock *lock);139 140struct drm_device;141struct drm_crtc;142struct drm_plane;143 144void drm_modeset_lock_all(struct drm_device *dev);145void drm_modeset_unlock_all(struct drm_device *dev);146void drm_warn_on_modeset_not_all_locked(struct drm_device *dev);147 148int drm_modeset_lock_all_ctx(struct drm_device *dev,149 struct drm_modeset_acquire_ctx *ctx);150 151/**152 * DRM_MODESET_LOCK_ALL_BEGIN - Helper to acquire modeset locks153 * @dev: drm device154 * @ctx: local modeset acquire context, will be dereferenced155 * @flags: DRM_MODESET_ACQUIRE_* flags to pass to drm_modeset_acquire_init()156 * @ret: local ret/err/etc variable to track error status157 *158 * Use these macros to simplify grabbing all modeset locks using a local159 * context. This has the advantage of reducing boilerplate, but also properly160 * checking return values where appropriate.161 *162 * Any code run between BEGIN and END will be holding the modeset locks.163 *164 * This must be paired with DRM_MODESET_LOCK_ALL_END(). We will jump back and165 * forth between the labels on deadlock and error conditions.166 *167 * Drivers can acquire additional modeset locks. If any lock acquisition168 * fails, the control flow needs to jump to DRM_MODESET_LOCK_ALL_END() with169 * the @ret parameter containing the return value of drm_modeset_lock().170 *171 * Returns:172 * The only possible value of ret immediately after DRM_MODESET_LOCK_ALL_BEGIN()173 * is 0, so no error checking is necessary174 */175#define DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, flags, ret) \176 if (!drm_drv_uses_atomic_modeset(dev)) \177 mutex_lock(&dev->mode_config.mutex); \178 drm_modeset_acquire_init(&ctx, flags); \179modeset_lock_retry: \180 ret = drm_modeset_lock_all_ctx(dev, &ctx); \181 if (ret) \182 goto modeset_lock_fail;183 184/**185 * DRM_MODESET_LOCK_ALL_END - Helper to release and cleanup modeset locks186 * @dev: drm device187 * @ctx: local modeset acquire context, will be dereferenced188 * @ret: local ret/err/etc variable to track error status189 *190 * The other side of DRM_MODESET_LOCK_ALL_BEGIN(). It will bounce back to BEGIN191 * if ret is -EDEADLK.192 *193 * It's important that you use the same ret variable for begin and end so194 * deadlock conditions are properly handled.195 *196 * Returns:197 * ret will be untouched unless it is -EDEADLK on entry. That means that if you198 * successfully acquire the locks, ret will be whatever your code sets it to. If199 * there is a deadlock or other failure with acquire or backoff, ret will be set200 * to that failure. In both of these cases the code between BEGIN/END will not201 * be run, so the failure will reflect the inability to grab the locks.202 */203#define DRM_MODESET_LOCK_ALL_END(dev, ctx, ret) \204modeset_lock_fail: \205 if (ret == -EDEADLK) { \206 ret = drm_modeset_backoff(&ctx); \207 if (!ret) \208 goto modeset_lock_retry; \209 } \210 drm_modeset_drop_locks(&ctx); \211 drm_modeset_acquire_fini(&ctx); \212 if (!drm_drv_uses_atomic_modeset(dev)) \213 mutex_unlock(&dev->mode_config.mutex);214 215#endif /* DRM_MODESET_LOCK_H_ */216