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Diffstat (limited to 'include/linux/fence.h')
| -rw-r--r-- | include/linux/fence.h | 378 |
1 files changed, 0 insertions, 378 deletions
diff --git a/include/linux/fence.h b/include/linux/fence.h deleted file mode 100644 index 0d763053f97a..000000000000 --- a/include/linux/fence.h +++ /dev/null @@ -1,378 +0,0 @@ -/* - * Fence mechanism for dma-buf to allow for asynchronous dma access - * - * Copyright (C) 2012 Canonical Ltd - * Copyright (C) 2012 Texas Instruments - * - * Authors: - * Rob Clark <robdclark@gmail.com> - * Maarten Lankhorst <maarten.lankhorst@canonical.com> - * - * This program is free software; you can redistribute it and/or modify it - * under the terms of the GNU General Public License version 2 as published by - * the Free Software Foundation. - * - * This program is distributed in the hope that it will be useful, but WITHOUT - * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or - * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for - * more details. - */ - -#ifndef __LINUX_FENCE_H -#define __LINUX_FENCE_H - -#include <linux/err.h> -#include <linux/wait.h> -#include <linux/list.h> -#include <linux/bitops.h> -#include <linux/kref.h> -#include <linux/sched.h> -#include <linux/printk.h> -#include <linux/rcupdate.h> - -struct fence; -struct fence_ops; -struct fence_cb; - -/** - * struct fence - software synchronization primitive - * @refcount: refcount for this fence - * @ops: fence_ops associated with this fence - * @rcu: used for releasing fence with kfree_rcu - * @cb_list: list of all callbacks to call - * @lock: spin_lock_irqsave used for locking - * @context: execution context this fence belongs to, returned by - * fence_context_alloc() - * @seqno: the sequence number of this fence inside the execution context, - * can be compared to decide which fence would be signaled later. - * @flags: A mask of FENCE_FLAG_* defined below - * @timestamp: Timestamp when the fence was signaled. - * @status: Optional, only valid if < 0, must be set before calling - * fence_signal, indicates that the fence has completed with an error. - * - * the flags member must be manipulated and read using the appropriate - * atomic ops (bit_*), so taking the spinlock will not be needed most - * of the time. - * - * FENCE_FLAG_SIGNALED_BIT - fence is already signaled - * FENCE_FLAG_ENABLE_SIGNAL_BIT - enable_signaling might have been called* - * FENCE_FLAG_USER_BITS - start of the unused bits, can be used by the - * implementer of the fence for its own purposes. Can be used in different - * ways by different fence implementers, so do not rely on this. - * - * Since atomic bitops are used, this is not guaranteed to be the case. - * Particularly, if the bit was set, but fence_signal was called right - * before this bit was set, it would have been able to set the - * FENCE_FLAG_SIGNALED_BIT, before enable_signaling was called. - * Adding a check for FENCE_FLAG_SIGNALED_BIT after setting - * FENCE_FLAG_ENABLE_SIGNAL_BIT closes this race, and makes sure that - * after fence_signal was called, any enable_signaling call will have either - * been completed, or never called at all. - */ -struct fence { - struct kref refcount; - const struct fence_ops *ops; - struct rcu_head rcu; - struct list_head cb_list; - spinlock_t *lock; - u64 context; - unsigned seqno; - unsigned long flags; - ktime_t timestamp; - int status; -}; - -enum fence_flag_bits { - FENCE_FLAG_SIGNALED_BIT, - FENCE_FLAG_ENABLE_SIGNAL_BIT, - FENCE_FLAG_USER_BITS, /* must always be last member */ -}; - -typedef void (*fence_func_t)(struct fence *fence, struct fence_cb *cb); - -/** - * struct fence_cb - callback for fence_add_callback - * @node: used by fence_add_callback to append this struct to fence::cb_list - * @func: fence_func_t to call - * - * This struct will be initialized by fence_add_callback, additional - * data can be passed along by embedding fence_cb in another struct. - */ -struct fence_cb { - struct list_head node; - fence_func_t func; -}; - -/** - * struct fence_ops - operations implemented for fence - * @get_driver_name: returns the driver name. - * @get_timeline_name: return the name of the context this fence belongs to. - * @enable_signaling: enable software signaling of fence. - * @signaled: [optional] peek whether the fence is signaled, can be null. - * @wait: custom wait implementation, or fence_default_wait. - * @release: [optional] called on destruction of fence, can be null - * @fill_driver_data: [optional] callback to fill in free-form debug info - * Returns amount of bytes filled, or -errno. - * @fence_value_str: [optional] fills in the value of the fence as a string - * @timeline_value_str: [optional] fills in the current value of the timeline - * as a string - * - * Notes on enable_signaling: - * For fence implementations that have the capability for hw->hw - * signaling, they can implement this op to enable the necessary - * irqs, or insert commands into cmdstream, etc. This is called - * in the first wait() or add_callback() path to let the fence - * implementation know that there is another driver waiting on - * the signal (ie. hw->sw case). - * - * This function can be called called from atomic context, but not - * from irq context, so normal spinlocks can be used. - * - * A return value of false indicates the fence already passed, - * or some failure occurred that made it impossible to enable - * signaling. True indicates successful enabling. - * - * fence->status may be set in enable_signaling, but only when false is - * returned. - * - * Calling fence_signal before enable_signaling is called allows - * for a tiny race window in which enable_signaling is called during, - * before, or after fence_signal. To fight this, it is recommended - * that before enable_signaling returns true an extra reference is - * taken on the fence, to be released when the fence is signaled. - * This will mean fence_signal will still be called twice, but - * the second time will be a noop since it was already signaled. - * - * Notes on signaled: - * May set fence->status if returning true. - * - * Notes on wait: - * Must not be NULL, set to fence_default_wait for default implementation. - * the fence_default_wait implementation should work for any fence, as long - * as enable_signaling works correctly. - * - * Must return -ERESTARTSYS if the wait is intr = true and the wait was - * interrupted, and remaining jiffies if fence has signaled, or 0 if wait - * timed out. Can also return other error values on custom implementations, - * which should be treated as if the fence is signaled. For example a hardware - * lockup could be reported like that. - * - * Notes on release: - * Can be NULL, this function allows additional commands to run on - * destruction of the fence. Can be called from irq context. - * If pointer is set to NULL, kfree will get called instead. - */ - -struct fence_ops { - const char * (*get_driver_name)(struct fence *fence); - const char * (*get_timeline_name)(struct fence *fence); - bool (*enable_signaling)(struct fence *fence); - bool (*signaled)(struct fence *fence); - signed long (*wait)(struct fence *fence, bool intr, signed long timeout); - void (*release)(struct fence *fence); - - int (*fill_driver_data)(struct fence *fence, void *data, int size); - void (*fence_value_str)(struct fence *fence, char *str, int size); - void (*timeline_value_str)(struct fence *fence, char *str, int size); -}; - -void fence_init(struct fence *fence, const struct fence_ops *ops, - spinlock_t *lock, u64 context, unsigned seqno); - -void fence_release(struct kref *kref); -void fence_free(struct fence *fence); - -/** - * fence_get - increases refcount of the fence - * @fence: [in] fence to increase refcount of - * - * Returns the same fence, with refcount increased by 1. - */ -static inline struct fence *fence_get(struct fence *fence) -{ - if (fence) - kref_get(&fence->refcount); - return fence; -} - -/** - * fence_get_rcu - get a fence from a reservation_object_list with rcu read lock - * @fence: [in] fence to increase refcount of - * - * Function returns NULL if no refcount could be obtained, or the fence. - */ -static inline struct fence *fence_get_rcu(struct fence *fence) -{ - if (kref_get_unless_zero(&fence->refcount)) - return fence; - else - return NULL; -} - -/** - * fence_put - decreases refcount of the fence - * @fence: [in] fence to reduce refcount of - */ -static inline void fence_put(struct fence *fence) -{ - if (fence) - kref_put(&fence->refcount, fence_release); -} - -int fence_signal(struct fence *fence); -int fence_signal_locked(struct fence *fence); -signed long fence_default_wait(struct fence *fence, bool intr, signed long timeout); -int fence_add_callback(struct fence *fence, struct fence_cb *cb, - fence_func_t func); -bool fence_remove_callback(struct fence *fence, struct fence_cb *cb); -void fence_enable_sw_signaling(struct fence *fence); - -/** - * fence_is_signaled_locked - Return an indication if the fence is signaled yet. - * @fence: [in] the fence to check - * - * Returns true if the fence was already signaled, false if not. Since this - * function doesn't enable signaling, it is not guaranteed to ever return - * true if fence_add_callback, fence_wait or fence_enable_sw_signaling - * haven't been called before. - * - * This function requires fence->lock to be held. - */ -static inline bool -fence_is_signaled_locked(struct fence *fence) -{ - if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) - return true; - - if (fence->ops->signaled && fence->ops->signaled(fence)) { - fence_signal_locked(fence); - return true; - } - - return false; -} - -/** - * fence_is_signaled - Return an indication if the fence is signaled yet. - * @fence: [in] the fence to check - * - * Returns true if the fence was already signaled, false if not. Since this - * function doesn't enable signaling, it is not guaranteed to ever return - * true if fence_add_callback, fence_wait or fence_enable_sw_signaling - * haven't been called before. - * - * It's recommended for seqno fences to call fence_signal when the - * operation is complete, it makes it possible to prevent issues from - * wraparound between time of issue and time of use by checking the return - * value of this function before calling hardware-specific wait instructions. - */ -static inline bool -fence_is_signaled(struct fence *fence) -{ - if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) - return true; - - if (fence->ops->signaled && fence->ops->signaled(fence)) { - fence_signal(fence); - return true; - } - - return false; -} - -/** - * fence_is_later - return if f1 is chronologically later than f2 - * @f1: [in] the first fence from the same context - * @f2: [in] the second fence from the same context - * - * Returns true if f1 is chronologically later than f2. Both fences must be - * from the same context, since a seqno is not re-used across contexts. - */ -static inline bool fence_is_later(struct fence *f1, struct fence *f2) -{ - if (WARN_ON(f1->context != f2->context)) - return false; - - return (int)(f1->seqno - f2->seqno) > 0; -} - -/** - * fence_later - return the chronologically later fence - * @f1: [in] the first fence from the same context - * @f2: [in] the second fence from the same context - * - * Returns NULL if both fences are signaled, otherwise the fence that would be - * signaled last. Both fences must be from the same context, since a seqno is - * not re-used across contexts. - */ -static inline struct fence *fence_later(struct fence *f1, struct fence *f2) -{ - if (WARN_ON(f1->context != f2->context)) - return NULL; - - /* - * can't check just FENCE_FLAG_SIGNALED_BIT here, it may never have been - * set if enable_signaling wasn't called, and enabling that here is - * overkill. - */ - if (fence_is_later(f1, f2)) - return fence_is_signaled(f1) ? NULL : f1; - else - return fence_is_signaled(f2) ? NULL : f2; -} - -signed long fence_wait_timeout(struct fence *, bool intr, signed long timeout); -signed long fence_wait_any_timeout(struct fence **fences, uint32_t count, - bool intr, signed long timeout); - -/** - * fence_wait - sleep until the fence gets signaled - * @fence: [in] the fence to wait on - * @intr: [in] if true, do an interruptible wait - * - * This function will return -ERESTARTSYS if interrupted by a signal, - * or 0 if the fence was signaled. Other error values may be - * returned on custom implementations. - * - * Performs a synchronous wait on this fence. It is assumed the caller - * directly or indirectly holds a reference to the fence, otherwise the - * fence might be freed before return, resulting in undefined behavior. - */ -static inline signed long fence_wait(struct fence *fence, bool intr) -{ - signed long ret; - - /* Since fence_wait_timeout cannot timeout with - * MAX_SCHEDULE_TIMEOUT, only valid return values are - * -ERESTARTSYS and MAX_SCHEDULE_TIMEOUT. - */ - ret = fence_wait_timeout(fence, intr, MAX_SCHEDULE_TIMEOUT); - - return ret < 0 ? ret : 0; -} - -u64 fence_context_alloc(unsigned num); - -#define FENCE_TRACE(f, fmt, args...) \ - do { \ - struct fence *__ff = (f); \ - if (IS_ENABLED(CONFIG_FENCE_TRACE)) \ - pr_info("f %llu#%u: " fmt, \ - __ff->context, __ff->seqno, ##args); \ - } while (0) - -#define FENCE_WARN(f, fmt, args...) \ - do { \ - struct fence *__ff = (f); \ - pr_warn("f %llu#%u: " fmt, __ff->context, __ff->seqno, \ - ##args); \ - } while (0) - -#define FENCE_ERR(f, fmt, args...) \ - do { \ - struct fence *__ff = (f); \ - pr_err("f %llu#%u: " fmt, __ff->context, __ff->seqno, \ - ##args); \ - } while (0) - -#endif /* __LINUX_FENCE_H */ |