drm_modeset_lock.h

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/*
 * 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 {
 
    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 {
    /*
     * 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);
 
static inline void drm_modeset_lock_fini(struct drm_modeset_lock *lock)
{
    WARN_ON(!list_empty(&lock->head));
}
 
static inline bool drm_modeset_is_locked(struct drm_modeset_lock *lock)
{
    return ww_mutex_is_locked(&lock->mutex);
}
 
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);
 
#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;
 
#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_ */