OSCL-LXR linux-6.0.1/​include/​drm/​drm_modeset_lock.h	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 /*
  * 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_ */

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