/* * Fence mechanism for dma-buf and to allow for asynchronous dma access * * Copyright (C) 2012 Canonical Ltd * Copyright (C) 2012 Texas Instruments * * Authors: * Rob Clark * Maarten Lankhorst * * 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. */ #include #include #include #include #define CREATE_TRACE_POINTS #include EXPORT_TRACEPOINT_SYMBOL(fence_annotate_wait_on); EXPORT_TRACEPOINT_SYMBOL(fence_emit); /* * fence context counter: each execution context should have its own * fence context, this allows checking if fences belong to the same * context or not. One device can have multiple separate contexts, * and they're used if some engine can run independently of another. */ static atomic_t fence_context_counter = ATOMIC_INIT(0); /** * fence_context_alloc - allocate an array of fence contexts * @num: [in] amount of contexts to allocate * * This function will return the first index of the number of fences allocated. * The fence context is used for setting fence->context to a unique number. */ unsigned fence_context_alloc(unsigned num) { BUG_ON(!num); return atomic_add_return(num, &fence_context_counter) - num; } EXPORT_SYMBOL(fence_context_alloc); /** * fence_signal_locked - signal completion of a fence * @fence: the fence to signal * * Signal completion for software callbacks on a fence, this will unblock * fence_wait() calls and run all the callbacks added with * fence_add_callback(). Can be called multiple times, but since a fence * can only go from unsignaled to signaled state, it will only be effective * the first time. * * Unlike fence_signal, this function must be called with fence->lock held. */ int fence_signal_locked(struct fence *fence) { struct fence_cb *cur, *tmp; int ret = 0; if (WARN_ON(!fence)) return -EINVAL; if (!ktime_to_ns(fence->timestamp)) { fence->timestamp = ktime_get(); smp_mb__before_atomic(); } if (test_and_set_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) { ret = -EINVAL; /* * we might have raced with the unlocked fence_signal, * still run through all callbacks */ } else trace_fence_signaled(fence); list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) { list_del_init(&cur->node); cur->func(fence, cur); } return ret; } EXPORT_SYMBOL(fence_signal_locked); /** * fence_signal - signal completion of a fence * @fence: the fence to signal * * Signal completion for software callbacks on a fence, this will unblock * fence_wait() calls and run all the callbacks added with * fence_add_callback(). Can be called multiple times, but since a fence * can only go from unsignaled to signaled state, it will only be effective * the first time. */ int fence_signal(struct fence *fence) { unsigned long flags; if (!fence) return -EINVAL; if (!ktime_to_ns(fence->timestamp)) { fence->timestamp = ktime_get(); smp_mb__before_atomic(); } if (test_and_set_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) return -EINVAL; trace_fence_signaled(fence); if (test_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags)) { struct fence_cb *cur, *tmp; spin_lock_irqsave(fence->lock, flags); list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) { list_del_init(&cur->node); cur->func(fence, cur); } spin_unlock_irqrestore(fence->lock, flags); } return 0; } EXPORT_SYMBOL(fence_signal); /** * fence_wait_timeout - sleep until the fence gets signaled * or until timeout elapses * @fence: [in] the fence to wait on * @intr: [in] if true, do an interruptible wait * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT * * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the * remaining timeout in jiffies on success. Other error values may be * returned on custom implementations. * * Performs a synchronous wait on this fence. It is assumed the caller * directly or indirectly (buf-mgr between reservation and committing) * holds a reference to the fence, otherwise the fence might be * freed before return, resulting in undefined behavior. */ signed long fence_wait_timeout(struct fence *fence, bool intr, signed long timeout) { signed long ret; if (WARN_ON(timeout < 0)) return -EINVAL; trace_fence_wait_start(fence); ret = fence->ops->wait(fence, intr, timeout); trace_fence_wait_end(fence); return ret; } EXPORT_SYMBOL(fence_wait_timeout); void fence_release(struct kref *kref) { struct fence *fence = container_of(kref, struct fence, refcount); trace_fence_destroy(fence); BUG_ON(!list_empty(&fence->cb_list)); if (fence->ops->release) fence->ops->release(fence); else fence_free(fence); } EXPORT_SYMBOL(fence_release); void fence_free(struct fence *fence) { kfree_rcu(fence, rcu); } EXPORT_SYMBOL(fence_free); /** * fence_enable_sw_signaling - enable signaling on fence * @fence: [in] the fence to enable * * this will request for sw signaling to be enabled, to make the fence * complete as soon as possible */ void fence_enable_sw_signaling(struct fence *fence) { unsigned long flags; if (!test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags) && !test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) { trace_fence_enable_signal(fence); spin_lock_irqsave(fence->lock, flags); if (!fence->ops->enable_signaling(fence)) fence_signal_locked(fence); spin_unlock_irqrestore(fence->lock, flags); } } EXPORT_SYMBOL(fence_enable_sw_signaling); /** * fence_add_callback - add a callback to be called when the fence * is signaled * @fence: [in] the fence to wait on * @cb: [in] the callback to register * @func: [in] the function to call * * cb will be initialized by fence_add_callback, no initialization * by the caller is required. Any number of callbacks can be registered * to a fence, but a callback can only be registered to one fence at a time. * * Note that the callback can be called from an atomic context. If * fence is already signaled, this function will return -ENOENT (and * *not* call the callback) * * Add a software callback to the fence. Same restrictions apply to * refcount as it does to fence_wait, however the caller doesn't need to * keep a refcount to fence afterwards: when software access is enabled, * the creator of the fence is required to keep the fence alive until * after it signals with fence_signal. The callback itself can be called * from irq context. * */ int fence_add_callback(struct fence *fence, struct fence_cb *cb, fence_func_t func) { unsigned long flags; int ret = 0; bool was_set; if (WARN_ON(!fence || !func)) return -EINVAL; if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) { INIT_LIST_HEAD(&cb->node); return -ENOENT; } spin_lock_irqsave(fence->lock, flags); was_set = test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags); if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) ret = -ENOENT; else if (!was_set) { trace_fence_enable_signal(fence); if (!fence->ops->enable_signaling(fence)) { fence_signal_locked(fence); ret = -ENOENT; } } if (!ret) { cb->func = func; list_add_tail(&cb->node, &fence->cb_list); } else INIT_LIST_HEAD(&cb->node); spin_unlock_irqrestore(fence->lock, flags); return ret; } EXPORT_SYMBOL(fence_add_callback); /** * fence_remove_callback - remove a callback from the signaling list * @fence: [in] the fence to wait on * @cb: [in] the callback to remove * * Remove a previously queued callback from the fence. This function returns * true if the callback is successfully removed, or false if the fence has * already been signaled. * * *WARNING*: * Cancelling a callback should only be done if you really know what you're * doing, since deadlocks and race conditions could occur all too easily. For * this reason, it should only ever be done on hardware lockup recovery, * with a reference held to the fence. */ bool fence_remove_callback(struct fence *fence, struct fence_cb *cb) { unsigned long flags; bool ret; spin_lock_irqsave(fence->lock, flags); ret = !list_empty(&cb->node); if (ret) list_del_init(&cb->node); spin_unlock_irqrestore(fence->lock, flags); return ret; } EXPORT_SYMBOL(fence_remove_callback); struct default_wait_cb { struct fence_cb base; struct task_struct *task; }; static void fence_default_wait_cb(struct fence *fence, struct fence_cb *cb) { struct default_wait_cb *wait = container_of(cb, struct default_wait_cb, base); wake_up_state(wait->task, TASK_NORMAL); } /** * fence_default_wait - default sleep until the fence gets signaled * or until timeout elapses * @fence: [in] the fence to wait on * @intr: [in] if true, do an interruptible wait * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT * * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the * remaining timeout in jiffies on success. */ signed long fence_default_wait(struct fence *fence, bool intr, signed long timeout) { struct default_wait_cb cb; unsigned long flags; signed long ret = timeout; bool was_set; if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) return timeout; spin_lock_irqsave(fence->lock, flags); if (intr && signal_pending(current)) { ret = -ERESTARTSYS; goto out; } was_set = test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags); if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) goto out; if (!was_set) { trace_fence_enable_signal(fence); if (!fence->ops->enable_signaling(fence)) { fence_signal_locked(fence); goto out; } } cb.base.func = fence_default_wait_cb; cb.task = current; list_add(&cb.base.node, &fence->cb_list); while (!test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) { if (intr) __set_current_state(TASK_INTERRUPTIBLE); else __set_current_state(TASK_UNINTERRUPTIBLE); spin_unlock_irqrestore(fence->lock, flags); ret = schedule_timeout(ret); spin_lock_irqsave(fence->lock, flags); if (ret > 0 && intr && signal_pending(current)) ret = -ERESTARTSYS; } if (!list_empty(&cb.base.node)) list_del(&cb.base.node); __set_current_state(TASK_RUNNING); out: spin_unlock_irqrestore(fence->lock, flags); return ret; } EXPORT_SYMBOL(fence_default_wait); /** * fence_init - Initialize a custom fence. * @fence: [in] the fence to initialize * @ops: [in] the fence_ops for operations on this fence * @lock: [in] the irqsafe spinlock to use for locking this fence * @context: [in] the execution context this fence is run on * @seqno: [in] a linear increasing sequence number for this context * * Initializes an allocated fence, the caller doesn't have to keep its * refcount after committing with this fence, but it will need to hold a * refcount again if fence_ops.enable_signaling gets called. This can * be used for other implementing other types of fence. * * context and seqno are used for easy comparison between fences, allowing * to check which fence is later by simply using fence_later. */ void fence_init(struct fence *fence, const struct fence_ops *ops, spinlock_t *lock, unsigned context, unsigned seqno) { BUG_ON(!lock); BUG_ON(!ops || !ops->wait || !ops->enable_signaling || !ops->get_driver_name || !ops->get_timeline_name); kref_init(&fence->refcount); fence->ops = ops; INIT_LIST_HEAD(&fence->cb_list); fence->lock = lock; fence->context = context; fence->seqno = seqno; fence->flags = 0UL; trace_fence_init(fence); } EXPORT_SYMBOL(fence_init);