OpenCloudOS-Kernel/include/drm/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/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
* @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;
/*
* 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;
drm: Per-plane locking Turned out to be much simpler on top of my latest atomic stuff than what I've feared. Some details: - Drop the modeset_lock_all snakeoil in drm_plane_init. Same justification as for the equivalent change in drm_crtc_init done in commit d0fa1af40e784aaf7ebb7ba8a17b229bb3fa4c21 Author: Daniel Vetter <daniel.vetter@ffwll.ch> Date: Mon Sep 8 09:02:49 2014 +0200 drm: Drop modeset locking from crtc init function Without these the drm_modeset_lock_init would fall over the exact same way. - Since the atomic core code wraps the locking switching it to per-plane locks was a one-line change. - For the legacy ioctls add a plane argument to the locking helper so that we can grab the right plane lock (cursor or primary). Since the universal cursor plane might not be there, or someone really crazy might forgoe the primary plane even accept NULL. - Add some locking WARN_ON to the atomic helpers for good paranoid measure and to check that it all works out. Tested on my exynos atomic hackfest with full lockdep checks and ww backoff injection. v2: I've forgotten about the load-detect code in i915. v3: Thierry reported that in latest 3.18-rc vmwgfx doesn't compile any more due to commit 21e88620aa21b48d4f62d29275e3e2944a5ea2b5 Author: Rob Clark <robdclark@gmail.com> Date: Thu Oct 30 13:39:04 2014 -0400 drm/vmwgfx: fix lock breakage Rebased and fix this up. Cc: Thierry Reding <thierry.reding@gmail.com> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Reviewed-by: Sean Paul <seanpaul@chromium.org> Signed-off-by: Dave Airlie <airlied@redhat.com>
2014-11-11 17:12:00 +08:00
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) \
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
* @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(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);
#endif /* DRM_MODESET_LOCK_H_ */