215 lines
7.0 KiB
C
215 lines
7.0 KiB
C
/*
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* Copyright (C) 2014 Red Hat
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* Author: Rob Clark <robdclark@gmail.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
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* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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#ifndef DRM_MODESET_LOCK_H_
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#define DRM_MODESET_LOCK_H_
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#include <linux/types.h> /* stackdepot.h is not self-contained */
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#include <linux/stackdepot.h>
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#include <linux/ww_mutex.h>
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struct drm_modeset_lock;
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/**
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* struct drm_modeset_acquire_ctx - locking context (see ww_acquire_ctx)
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* @ww_ctx: base acquire ctx
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* @contended: used internally for -EDEADLK handling
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* @locked: list of held locks
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* @trylock_only: trylock mode used in atomic contexts/panic notifiers
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* @interruptible: whether interruptible locking should be used.
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*
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* Each thread competing for a set of locks must use one acquire
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* ctx. And if any lock fxn returns -EDEADLK, it must backoff and
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* retry.
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*/
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struct drm_modeset_acquire_ctx {
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struct ww_acquire_ctx ww_ctx;
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/*
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* Contended lock: if a lock is contended you should only call
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* drm_modeset_backoff() which drops locks and slow-locks the
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* contended lock.
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*/
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struct drm_modeset_lock *contended;
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/*
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* Stack depot for debugging when a contended lock was not backed off
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* from.
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*/
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depot_stack_handle_t stack_depot;
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/*
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* list of held locks (drm_modeset_lock)
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*/
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struct list_head locked;
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/*
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* Trylock mode, use only for panic handlers!
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*/
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bool trylock_only;
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/* Perform interruptible waits on this context. */
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bool interruptible;
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};
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/**
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* struct drm_modeset_lock - used for locking modeset resources.
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* @mutex: resource locking
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* @head: used to hold its place on &drm_atomi_state.locked list when
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* part of an atomic update
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*
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* Used for locking CRTCs and other modeset resources.
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*/
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struct drm_modeset_lock {
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/*
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* modeset lock
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*/
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struct ww_mutex mutex;
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/*
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* Resources that are locked as part of an atomic update are added
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* to a list (so we know what to unlock at the end).
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*/
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struct list_head head;
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};
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#define DRM_MODESET_ACQUIRE_INTERRUPTIBLE BIT(0)
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void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
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uint32_t flags);
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void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx);
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void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx);
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int drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx);
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void drm_modeset_lock_init(struct drm_modeset_lock *lock);
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/**
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* drm_modeset_lock_fini - cleanup lock
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* @lock: lock to cleanup
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*/
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static inline void drm_modeset_lock_fini(struct drm_modeset_lock *lock)
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{
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WARN_ON(!list_empty(&lock->head));
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}
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/**
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* drm_modeset_is_locked - equivalent to mutex_is_locked()
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* @lock: lock to check
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*/
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static inline bool drm_modeset_is_locked(struct drm_modeset_lock *lock)
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{
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return ww_mutex_is_locked(&lock->mutex);
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}
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/**
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* drm_modeset_lock_assert_held - equivalent to lockdep_assert_held()
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* @lock: lock to check
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*/
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static inline void drm_modeset_lock_assert_held(struct drm_modeset_lock *lock)
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{
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lockdep_assert_held(&lock->mutex.base);
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}
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int drm_modeset_lock(struct drm_modeset_lock *lock,
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struct drm_modeset_acquire_ctx *ctx);
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int __must_check drm_modeset_lock_single_interruptible(struct drm_modeset_lock *lock);
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void drm_modeset_unlock(struct drm_modeset_lock *lock);
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struct drm_device;
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struct drm_crtc;
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struct drm_plane;
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void drm_modeset_lock_all(struct drm_device *dev);
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void drm_modeset_unlock_all(struct drm_device *dev);
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void drm_warn_on_modeset_not_all_locked(struct drm_device *dev);
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int drm_modeset_lock_all_ctx(struct drm_device *dev,
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struct drm_modeset_acquire_ctx *ctx);
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/**
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* DRM_MODESET_LOCK_ALL_BEGIN - Helper to acquire modeset locks
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* @dev: drm device
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* @ctx: local modeset acquire context, will be dereferenced
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* @flags: DRM_MODESET_ACQUIRE_* flags to pass to drm_modeset_acquire_init()
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* @ret: local ret/err/etc variable to track error status
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*
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* Use these macros to simplify grabbing all modeset locks using a local
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* context. This has the advantage of reducing boilerplate, but also properly
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* checking return values where appropriate.
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*
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* Any code run between BEGIN and END will be holding the modeset locks.
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*
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* This must be paired with DRM_MODESET_LOCK_ALL_END(). We will jump back and
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* forth between the labels on deadlock and error conditions.
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*
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* Drivers can acquire additional modeset locks. If any lock acquisition
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* fails, the control flow needs to jump to DRM_MODESET_LOCK_ALL_END() with
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* the @ret parameter containing the return value of drm_modeset_lock().
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*
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* Returns:
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* The only possible value of ret immediately after DRM_MODESET_LOCK_ALL_BEGIN()
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* is 0, so no error checking is necessary
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*/
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#define DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, flags, ret) \
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if (!drm_drv_uses_atomic_modeset(dev)) \
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mutex_lock(&dev->mode_config.mutex); \
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drm_modeset_acquire_init(&ctx, flags); \
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modeset_lock_retry: \
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ret = drm_modeset_lock_all_ctx(dev, &ctx); \
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if (ret) \
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goto modeset_lock_fail;
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/**
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* DRM_MODESET_LOCK_ALL_END - Helper to release and cleanup modeset locks
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* @dev: drm device
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* @ctx: local modeset acquire context, will be dereferenced
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* @ret: local ret/err/etc variable to track error status
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*
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* The other side of DRM_MODESET_LOCK_ALL_BEGIN(). It will bounce back to BEGIN
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* if ret is -EDEADLK.
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*
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* It's important that you use the same ret variable for begin and end so
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* deadlock conditions are properly handled.
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*
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* Returns:
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* ret will be untouched unless it is -EDEADLK on entry. That means that if you
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* successfully acquire the locks, ret will be whatever your code sets it to. If
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* there is a deadlock or other failure with acquire or backoff, ret will be set
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* to that failure. In both of these cases the code between BEGIN/END will not
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* be run, so the failure will reflect the inability to grab the locks.
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*/
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#define DRM_MODESET_LOCK_ALL_END(dev, ctx, ret) \
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modeset_lock_fail: \
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if (ret == -EDEADLK) { \
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ret = drm_modeset_backoff(&ctx); \
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if (!ret) \
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goto modeset_lock_retry; \
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} \
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drm_modeset_drop_locks(&ctx); \
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drm_modeset_acquire_fini(&ctx); \
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if (!drm_drv_uses_atomic_modeset(dev)) \
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mutex_unlock(&dev->mode_config.mutex);
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#endif /* DRM_MODESET_LOCK_H_ */
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