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![Jammy Zhou](/assets/img/avatar_default.png)
When specified timeout is zero for fence_wait_timeout, just check if the fence is signaled or not without wait. Signed-off-by: Jammy Zhou <Jammy.Zhou@amd.com> Reviewed-by: Christian König <christian.koenig@amd.com> Reviewed-By: Maarten Lankhorst <maarten.lankhorst@canonical.com> Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
434 lines
12 KiB
C
434 lines
12 KiB
C
/*
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* Fence mechanism for dma-buf and to allow for asynchronous dma access
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*
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* Copyright (C) 2012 Canonical Ltd
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* Copyright (C) 2012 Texas Instruments
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*
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* Authors:
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* Rob Clark <robdclark@gmail.com>
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* Maarten Lankhorst <maarten.lankhorst@canonical.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*/
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#include <linux/slab.h>
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#include <linux/export.h>
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#include <linux/atomic.h>
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#include <linux/fence.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/fence.h>
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EXPORT_TRACEPOINT_SYMBOL(fence_annotate_wait_on);
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EXPORT_TRACEPOINT_SYMBOL(fence_emit);
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/*
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* fence context counter: each execution context should have its own
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* fence context, this allows checking if fences belong to the same
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* context or not. One device can have multiple separate contexts,
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* and they're used if some engine can run independently of another.
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*/
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static atomic_t fence_context_counter = ATOMIC_INIT(0);
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/**
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* fence_context_alloc - allocate an array of fence contexts
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* @num: [in] amount of contexts to allocate
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*
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* This function will return the first index of the number of fences allocated.
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* The fence context is used for setting fence->context to a unique number.
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*/
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unsigned fence_context_alloc(unsigned num)
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{
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BUG_ON(!num);
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return atomic_add_return(num, &fence_context_counter) - num;
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}
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EXPORT_SYMBOL(fence_context_alloc);
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/**
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* fence_signal_locked - signal completion of a fence
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* @fence: the fence to signal
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*
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* Signal completion for software callbacks on a fence, this will unblock
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* fence_wait() calls and run all the callbacks added with
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* fence_add_callback(). Can be called multiple times, but since a fence
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* can only go from unsignaled to signaled state, it will only be effective
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* the first time.
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*
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* Unlike fence_signal, this function must be called with fence->lock held.
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*/
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int fence_signal_locked(struct fence *fence)
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{
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struct fence_cb *cur, *tmp;
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int ret = 0;
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if (WARN_ON(!fence))
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return -EINVAL;
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if (!ktime_to_ns(fence->timestamp)) {
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fence->timestamp = ktime_get();
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smp_mb__before_atomic();
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}
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if (test_and_set_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
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ret = -EINVAL;
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/*
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* we might have raced with the unlocked fence_signal,
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* still run through all callbacks
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*/
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} else
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trace_fence_signaled(fence);
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list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
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list_del_init(&cur->node);
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cur->func(fence, cur);
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}
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return ret;
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}
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EXPORT_SYMBOL(fence_signal_locked);
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/**
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* fence_signal - signal completion of a fence
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* @fence: the fence to signal
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*
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* Signal completion for software callbacks on a fence, this will unblock
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* fence_wait() calls and run all the callbacks added with
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* fence_add_callback(). Can be called multiple times, but since a fence
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* can only go from unsignaled to signaled state, it will only be effective
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* the first time.
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*/
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int fence_signal(struct fence *fence)
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{
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unsigned long flags;
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if (!fence)
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return -EINVAL;
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if (!ktime_to_ns(fence->timestamp)) {
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fence->timestamp = ktime_get();
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smp_mb__before_atomic();
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}
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if (test_and_set_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
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return -EINVAL;
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trace_fence_signaled(fence);
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if (test_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags)) {
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struct fence_cb *cur, *tmp;
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spin_lock_irqsave(fence->lock, flags);
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list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
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list_del_init(&cur->node);
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cur->func(fence, cur);
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}
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spin_unlock_irqrestore(fence->lock, flags);
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}
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return 0;
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}
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EXPORT_SYMBOL(fence_signal);
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/**
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* fence_wait_timeout - sleep until the fence gets signaled
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* or until timeout elapses
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* @fence: [in] the fence to wait on
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* @intr: [in] if true, do an interruptible wait
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* @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
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*
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* Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
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* remaining timeout in jiffies on success. Other error values may be
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* returned on custom implementations.
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*
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* Performs a synchronous wait on this fence. It is assumed the caller
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* directly or indirectly (buf-mgr between reservation and committing)
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* holds a reference to the fence, otherwise the fence might be
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* freed before return, resulting in undefined behavior.
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*/
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signed long
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fence_wait_timeout(struct fence *fence, bool intr, signed long timeout)
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{
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signed long ret;
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if (WARN_ON(timeout < 0))
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return -EINVAL;
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if (timeout == 0)
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return fence_is_signaled(fence);
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trace_fence_wait_start(fence);
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ret = fence->ops->wait(fence, intr, timeout);
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trace_fence_wait_end(fence);
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return ret;
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}
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EXPORT_SYMBOL(fence_wait_timeout);
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void fence_release(struct kref *kref)
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{
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struct fence *fence =
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container_of(kref, struct fence, refcount);
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trace_fence_destroy(fence);
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BUG_ON(!list_empty(&fence->cb_list));
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if (fence->ops->release)
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fence->ops->release(fence);
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else
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fence_free(fence);
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}
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EXPORT_SYMBOL(fence_release);
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void fence_free(struct fence *fence)
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{
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kfree_rcu(fence, rcu);
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}
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EXPORT_SYMBOL(fence_free);
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/**
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* fence_enable_sw_signaling - enable signaling on fence
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* @fence: [in] the fence to enable
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*
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* this will request for sw signaling to be enabled, to make the fence
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* complete as soon as possible
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*/
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void fence_enable_sw_signaling(struct fence *fence)
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{
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unsigned long flags;
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if (!test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags) &&
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!test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
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trace_fence_enable_signal(fence);
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spin_lock_irqsave(fence->lock, flags);
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if (!fence->ops->enable_signaling(fence))
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fence_signal_locked(fence);
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spin_unlock_irqrestore(fence->lock, flags);
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}
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}
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EXPORT_SYMBOL(fence_enable_sw_signaling);
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/**
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* fence_add_callback - add a callback to be called when the fence
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* is signaled
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* @fence: [in] the fence to wait on
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* @cb: [in] the callback to register
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* @func: [in] the function to call
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*
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* cb will be initialized by fence_add_callback, no initialization
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* by the caller is required. Any number of callbacks can be registered
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* to a fence, but a callback can only be registered to one fence at a time.
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*
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* Note that the callback can be called from an atomic context. If
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* fence is already signaled, this function will return -ENOENT (and
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* *not* call the callback)
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*
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* Add a software callback to the fence. Same restrictions apply to
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* refcount as it does to fence_wait, however the caller doesn't need to
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* keep a refcount to fence afterwards: when software access is enabled,
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* the creator of the fence is required to keep the fence alive until
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* after it signals with fence_signal. The callback itself can be called
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* from irq context.
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*
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*/
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int fence_add_callback(struct fence *fence, struct fence_cb *cb,
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fence_func_t func)
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{
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unsigned long flags;
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int ret = 0;
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bool was_set;
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if (WARN_ON(!fence || !func))
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return -EINVAL;
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if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
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INIT_LIST_HEAD(&cb->node);
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return -ENOENT;
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}
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spin_lock_irqsave(fence->lock, flags);
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was_set = test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags);
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if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
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ret = -ENOENT;
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else if (!was_set) {
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trace_fence_enable_signal(fence);
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if (!fence->ops->enable_signaling(fence)) {
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fence_signal_locked(fence);
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ret = -ENOENT;
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}
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}
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if (!ret) {
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cb->func = func;
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list_add_tail(&cb->node, &fence->cb_list);
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} else
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INIT_LIST_HEAD(&cb->node);
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spin_unlock_irqrestore(fence->lock, flags);
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return ret;
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}
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EXPORT_SYMBOL(fence_add_callback);
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/**
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* fence_remove_callback - remove a callback from the signaling list
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* @fence: [in] the fence to wait on
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* @cb: [in] the callback to remove
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*
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* Remove a previously queued callback from the fence. This function returns
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* true if the callback is successfully removed, or false if the fence has
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* already been signaled.
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*
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* *WARNING*:
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* Cancelling a callback should only be done if you really know what you're
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* doing, since deadlocks and race conditions could occur all too easily. For
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* this reason, it should only ever be done on hardware lockup recovery,
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* with a reference held to the fence.
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*/
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bool
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fence_remove_callback(struct fence *fence, struct fence_cb *cb)
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{
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unsigned long flags;
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bool ret;
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spin_lock_irqsave(fence->lock, flags);
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ret = !list_empty(&cb->node);
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if (ret)
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list_del_init(&cb->node);
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spin_unlock_irqrestore(fence->lock, flags);
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return ret;
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}
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EXPORT_SYMBOL(fence_remove_callback);
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struct default_wait_cb {
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struct fence_cb base;
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struct task_struct *task;
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};
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static void
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fence_default_wait_cb(struct fence *fence, struct fence_cb *cb)
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{
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struct default_wait_cb *wait =
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container_of(cb, struct default_wait_cb, base);
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wake_up_state(wait->task, TASK_NORMAL);
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}
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/**
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* fence_default_wait - default sleep until the fence gets signaled
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* or until timeout elapses
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* @fence: [in] the fence to wait on
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* @intr: [in] if true, do an interruptible wait
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* @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
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*
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* Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
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* remaining timeout in jiffies on success.
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*/
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signed long
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fence_default_wait(struct fence *fence, bool intr, signed long timeout)
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{
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struct default_wait_cb cb;
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unsigned long flags;
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signed long ret = timeout;
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bool was_set;
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if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
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return timeout;
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spin_lock_irqsave(fence->lock, flags);
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if (intr && signal_pending(current)) {
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ret = -ERESTARTSYS;
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goto out;
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}
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was_set = test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags);
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if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
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goto out;
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if (!was_set) {
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trace_fence_enable_signal(fence);
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if (!fence->ops->enable_signaling(fence)) {
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fence_signal_locked(fence);
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goto out;
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}
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}
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cb.base.func = fence_default_wait_cb;
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cb.task = current;
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list_add(&cb.base.node, &fence->cb_list);
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while (!test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) {
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if (intr)
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__set_current_state(TASK_INTERRUPTIBLE);
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else
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__set_current_state(TASK_UNINTERRUPTIBLE);
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spin_unlock_irqrestore(fence->lock, flags);
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ret = schedule_timeout(ret);
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spin_lock_irqsave(fence->lock, flags);
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if (ret > 0 && intr && signal_pending(current))
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ret = -ERESTARTSYS;
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}
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if (!list_empty(&cb.base.node))
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list_del(&cb.base.node);
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__set_current_state(TASK_RUNNING);
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out:
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spin_unlock_irqrestore(fence->lock, flags);
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return ret;
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}
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EXPORT_SYMBOL(fence_default_wait);
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/**
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* fence_init - Initialize a custom fence.
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* @fence: [in] the fence to initialize
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* @ops: [in] the fence_ops for operations on this fence
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* @lock: [in] the irqsafe spinlock to use for locking this fence
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* @context: [in] the execution context this fence is run on
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* @seqno: [in] a linear increasing sequence number for this context
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*
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* Initializes an allocated fence, the caller doesn't have to keep its
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* refcount after committing with this fence, but it will need to hold a
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* refcount again if fence_ops.enable_signaling gets called. This can
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* be used for other implementing other types of fence.
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*
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* context and seqno are used for easy comparison between fences, allowing
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* to check which fence is later by simply using fence_later.
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*/
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void
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fence_init(struct fence *fence, const struct fence_ops *ops,
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spinlock_t *lock, unsigned context, unsigned seqno)
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{
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BUG_ON(!lock);
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BUG_ON(!ops || !ops->wait || !ops->enable_signaling ||
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!ops->get_driver_name || !ops->get_timeline_name);
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kref_init(&fence->refcount);
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fence->ops = ops;
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INIT_LIST_HEAD(&fence->cb_list);
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fence->lock = lock;
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fence->context = context;
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fence->seqno = seqno;
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fence->flags = 0UL;
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trace_fence_init(fence);
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}
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EXPORT_SYMBOL(fence_init);
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