/* * 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/types.h> /* stackdepot.h is not self-contained */#include <linux/stackdepot.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 * @stack_depot: used internally for contention debugging * @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; 	/*	 * Stack depot for debugging when a contended lock was not backed off	 * from.	 */	depot_stack_handle_t stack_depot; 	/*	 * 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 its 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);} /** * drm_modeset_lock_assert_held - equivalent to lockdep_assert_held() * @lock: lock to check */static inline void drm_modeset_lock_assert_held(struct drm_modeset_lock *lock){	lockdep_assert_held(&lock->mutex.base);} 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)		\	if (!drm_drv_uses_atomic_modeset(dev))				\		mutex_lock(&dev->mode_config.mutex);			\	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 * @dev: drm device * @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(dev, 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);					\	if (!drm_drv_uses_atomic_modeset(dev))				\		mutex_unlock(&dev->mode_config.mutex); #endif /* DRM_MODESET_LOCK_H_ */