Move the duplicated code within dma-fence.c into the header for wider reuse. In the process apply a small micro-optimisation to only prune the fence->cb_list once rather than use list_del on every entry.
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursu...@intel.com> --- drivers/dma-buf/Makefile | 10 +- drivers/dma-buf/dma-fence-trace.c | 28 +++ drivers/dma-buf/dma-fence.c | 33 +-- drivers/gpu/drm/i915/gt/intel_breadcrumbs.c | 32 +-- include/linux/dma-fence-impl.h | 83 +++++++ include/linux/dma-fence-types.h | 258 ++++++++++++++++++++ include/linux/dma-fence.h | 228 +---------------- 7 files changed, 386 insertions(+), 286 deletions(-) create mode 100644 drivers/dma-buf/dma-fence-trace.c create mode 100644 include/linux/dma-fence-impl.h create mode 100644 include/linux/dma-fence-types.h diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile index e8c7310cb800..65c43778e571 100644 --- a/drivers/dma-buf/Makefile +++ b/drivers/dma-buf/Makefile @@ -1,6 +1,12 @@ # SPDX-License-Identifier: GPL-2.0-only -obj-y := dma-buf.o dma-fence.o dma-fence-array.o dma-fence-chain.o \ - reservation.o seqno-fence.o +obj-y := \ + dma-buf.o \ + dma-fence.o \ + dma-fence-array.o \ + dma-fence-chain.o \ + dma-fence-trace.o \ + reservation.o \ + seqno-fence.o obj-$(CONFIG_SYNC_FILE) += sync_file.o obj-$(CONFIG_SW_SYNC) += sw_sync.o sync_debug.o obj-$(CONFIG_UDMABUF) += udmabuf.o diff --git a/drivers/dma-buf/dma-fence-trace.c b/drivers/dma-buf/dma-fence-trace.c new file mode 100644 index 000000000000..eb6f282be4c0 --- /dev/null +++ b/drivers/dma-buf/dma-fence-trace.c @@ -0,0 +1,28 @@ +/* + * 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 <robdcl...@gmail.com> + * Maarten Lankhorst <maarten.lankho...@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. + */ + +#include <linux/dma-fence-types.h> + +#define CREATE_TRACE_POINTS +#include <trace/events/dma_fence.h> + +EXPORT_TRACEPOINT_SYMBOL(dma_fence_emit); +EXPORT_TRACEPOINT_SYMBOL(dma_fence_enable_signal); +EXPORT_TRACEPOINT_SYMBOL(dma_fence_signaled); diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index 59ac96ec7ba8..027a6a894abd 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -14,15 +14,9 @@ #include <linux/export.h> #include <linux/atomic.h> #include <linux/dma-fence.h> +#include <linux/dma-fence-impl.h> #include <linux/sched/signal.h> -#define CREATE_TRACE_POINTS -#include <trace/events/dma_fence.h> - -EXPORT_TRACEPOINT_SYMBOL(dma_fence_emit); -EXPORT_TRACEPOINT_SYMBOL(dma_fence_enable_signal); -EXPORT_TRACEPOINT_SYMBOL(dma_fence_signaled); - static DEFINE_SPINLOCK(dma_fence_stub_lock); static struct dma_fence dma_fence_stub; @@ -128,7 +122,6 @@ EXPORT_SYMBOL(dma_fence_context_alloc); */ int dma_fence_signal_locked(struct dma_fence *fence) { - struct dma_fence_cb *cur, *tmp; int ret = 0; lockdep_assert_held(fence->lock); @@ -136,7 +129,7 @@ int dma_fence_signal_locked(struct dma_fence *fence) if (WARN_ON(!fence)) return -EINVAL; - if (test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) { + if (!__dma_fence_signal(fence)) { ret = -EINVAL; /* @@ -144,15 +137,10 @@ int dma_fence_signal_locked(struct dma_fence *fence) * still run through all callbacks */ } else { - fence->timestamp = ktime_get(); - set_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags); - trace_dma_fence_signaled(fence); + __dma_fence_signal__timestamp(fence, ktime_get()); } - list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) { - list_del_init(&cur->node); - cur->func(fence, cur); - } + __dma_fence_signal__notify(fence); return ret; } EXPORT_SYMBOL(dma_fence_signal_locked); @@ -177,21 +165,14 @@ int dma_fence_signal(struct dma_fence *fence) if (!fence) return -EINVAL; - if (test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) + if (!__dma_fence_signal(fence)) return -EINVAL; - fence->timestamp = ktime_get(); - set_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags); - trace_dma_fence_signaled(fence); + __dma_fence_signal__timestamp(fence, ktime_get()); if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags)) { - struct dma_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); - } + __dma_fence_signal__notify(fence); spin_unlock_irqrestore(fence->lock, flags); } return 0; diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c index e1bbc9b428cd..65de5c45a233 100644 --- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c @@ -22,8 +22,7 @@ * */ -#include <linux/kthread.h> -#include <trace/events/dma_fence.h> +#include <linux/dma-fence-impl.h> #include <uapi/linux/sched/types.h> #include "i915_drv.h" @@ -98,35 +97,6 @@ check_signal_order(struct intel_context *ce, struct i915_request *rq) return true; } -static bool -__dma_fence_signal(struct dma_fence *fence) -{ - return !test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags); -} - -static void -__dma_fence_signal__timestamp(struct dma_fence *fence, ktime_t timestamp) -{ - fence->timestamp = timestamp; - set_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags); - trace_dma_fence_signaled(fence); -} - -static void -__dma_fence_signal__notify(struct dma_fence *fence) -{ - struct dma_fence_cb *cur, *tmp; - - lockdep_assert_held(fence->lock); - lockdep_assert_irqs_disabled(); - - list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) { - INIT_LIST_HEAD(&cur->node); - cur->func(fence, cur); - } - INIT_LIST_HEAD(&fence->cb_list); -} - void intel_engine_breadcrumbs_irq(struct intel_engine_cs *engine) { struct intel_breadcrumbs *b = &engine->breadcrumbs; diff --git a/include/linux/dma-fence-impl.h b/include/linux/dma-fence-impl.h new file mode 100644 index 000000000000..7372021cf082 --- /dev/null +++ b/include/linux/dma-fence-impl.h @@ -0,0 +1,83 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Fence mechanism for dma-buf to allow for asynchronous dma access + * + * Copyright (C) 2012 Canonical Ltd + * Copyright (C) 2012 Texas Instruments + * + * Authors: + * Rob Clark <robdcl...@gmail.com> + * Maarten Lankhorst <maarten.lankho...@canonical.com> + */ + +#ifndef __LINUX_DMA_FENCE_IMPL_H +#define __LINUX_DMA_FENCE_IMPL_H + +#include <linux/dma-fence.h> +#include <linux/lockdep.h> +#include <linux/list.h> +#include <linux/ktime.h> + +#include <trace/events/dma_fence.h> + +/** + * __dma_fence_signal: Mark a fence as signaled + * @fence: the dma fence to mark + * + * The first step of the dma_fence_signal() implementation is to atomically + * mark the fence as signaled. + * + * Returns: true if the fence was not previously signaled, false if it was + * already signaled. + */ +static inline bool +__dma_fence_signal(struct dma_fence *fence) +{ + return !test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags); +} + +/** + * __dma_fence_signal__timestamp: sets the signaling timestamp + * @fence: the dma fence + * @timestamp: the monotonic timestamp (e.g. ktime_get_mono()) + * + * The second step of the dma_fence_signal() implementation it to record + * the siganling timestamp. + * + * The dma-fence stores a timestamp of when it was signaled for inspection + * by userspace. This timestamp is typically the CPU time at which the + * signal was raised, but could be a HW timestamp generated by the event + * itself. Either way, it must be set on the signaled fence before + * callbacks are notified. + */ +static inline void +__dma_fence_signal__timestamp(struct dma_fence *fence, ktime_t timestamp) +{ + fence->timestamp = timestamp; + set_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags); + trace_dma_fence_signaled(fence); +} + +/** + * __dma_fence_signal__notify: notify observers of the signal event + * @fence: the dma fence + * + * The final step of the dma_fence_signal() implementation is to notify + * all observers (dma_fence_add_callback()) of the signal event. This must + * be called with the fence->lock already held and irqsoff. + */ +static inline void +__dma_fence_signal__notify(struct dma_fence *fence) +{ + struct dma_fence_cb *cur, *tmp; + + lockdep_assert_held(fence->lock); + + list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) { + INIT_LIST_HEAD(&cur->node); + cur->func(fence, cur); + } + INIT_LIST_HEAD(&fence->cb_list); +} + +#endif /* __LINUX_DMA_FENCE_IMPL_H */ diff --git a/include/linux/dma-fence-types.h b/include/linux/dma-fence-types.h new file mode 100644 index 000000000000..81e22d9ed174 --- /dev/null +++ b/include/linux/dma-fence-types.h @@ -0,0 +1,258 @@ +/* + * Fence mechanism for dma-buf to allow for asynchronous dma access + * + * Copyright (C) 2012 Canonical Ltd + * Copyright (C) 2012 Texas Instruments + * + * Authors: + * Rob Clark <robdcl...@gmail.com> + * Maarten Lankhorst <maarten.lankho...@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_DMA_FENCE_TYPES_H +#define __LINUX_DMA_FENCE_TYPES_H + +#include <linux/list.h> +#include <linux/kref.h> +#include <linux/ktime.h> +#include <linux/rcupdate.h> +#include <linux/spinlock.h> +#include <linux/types.h> + +struct dma_fence; +struct dma_fence_ops; +struct dma_fence_cb; + +/** + * struct dma_fence - software synchronization primitive + * @refcount: refcount for this fence + * @ops: dma_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 + * dma_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 DMA_FENCE_FLAG_* defined below + * @timestamp: Timestamp when the fence was signaled. + * @error: Optional, only valid if < 0, must be set before calling + * dma_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. + * + * DMA_FENCE_FLAG_SIGNALED_BIT - fence is already signaled + * DMA_FENCE_FLAG_TIMESTAMP_BIT - timestamp recorded for fence signaling + * DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT - enable_signaling might have been called + * DMA_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 dma_fence_signal was called right + * before this bit was set, it would have been able to set the + * DMA_FENCE_FLAG_SIGNALED_BIT, before enable_signaling was called. + * Adding a check for DMA_FENCE_FLAG_SIGNALED_BIT after setting + * DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT closes this race, and makes sure that + * after dma_fence_signal was called, any enable_signaling call will have either + * been completed, or never called at all. + */ +struct dma_fence { + struct kref refcount; + const struct dma_fence_ops *ops; + /* We clear the callback list on kref_put so that by the time we + * release the fence it is unused. No one should be adding to the cb_list + * that they don't themselves hold a reference for. + */ + union { + struct rcu_head rcu; + struct list_head cb_list; + }; + spinlock_t *lock; + u64 context; + u64 seqno; + unsigned long flags; + ktime_t timestamp; + int error; +}; + +enum dma_fence_flag_bits { + DMA_FENCE_FLAG_SIGNALED_BIT, + DMA_FENCE_FLAG_TIMESTAMP_BIT, + DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, + DMA_FENCE_FLAG_USER_BITS, /* must always be last member */ +}; + +typedef void (*dma_fence_func_t)(struct dma_fence *fence, + struct dma_fence_cb *cb); + +/** + * struct dma_fence_cb - callback for dma_fence_add_callback() + * @node: used by dma_fence_add_callback() to append this struct to fence::cb_list + * @func: dma_fence_func_t to call + * + * This struct will be initialized by dma_fence_add_callback(), additional + * data can be passed along by embedding dma_fence_cb in another struct. + */ +struct dma_fence_cb { + struct list_head node; + dma_fence_func_t func; +}; + +/** + * struct dma_fence_ops - operations implemented for fence + * + */ +struct dma_fence_ops { + /** + * @use_64bit_seqno: + * + * True if this dma_fence implementation uses 64bit seqno, false + * otherwise. + */ + bool use_64bit_seqno; + + /** + * @get_driver_name: + * + * Returns the driver name. This is a callback to allow drivers to + * compute the name at runtime, without having it to store permanently + * for each fence, or build a cache of some sort. + * + * This callback is mandatory. + */ + const char * (*get_driver_name)(struct dma_fence *fence); + + /** + * @get_timeline_name: + * + * Return the name of the context this fence belongs to. This is a + * callback to allow drivers to compute the name at runtime, without + * having it to store permanently for each fence, or build a cache of + * some sort. + * + * This callback is mandatory. + */ + const char * (*get_timeline_name)(struct dma_fence *fence); + + /** + * @enable_signaling: + * + * Enable software signaling of fence. + * + * For fence implementations that have the capability for hw->hw + * signaling, they can implement this op to enable the necessary + * interrupts, or insert commands into cmdstream, etc, to avoid these + * costly operations for the common case where only hw->hw + * synchronization is required. This is called in the first + * dma_fence_wait() or dma_fence_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 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. + * + * &dma_fence.error may be set in enable_signaling, but only when false + * is returned. + * + * Since many implementations can call dma_fence_signal() even before + * @enable_signaling has been called there's a race window, where the + * dma_fence_signal() might result in the final fence reference being + * released and its memory freed. To avoid this, implementations of + * this callback should grab their own reference using dma_fence_get(), + * to be released when the fence is signalled (through e.g. the + * interrupt handler). + * + * This callback is optional. If this callback is not present, then the + * driver must always have signaling enabled. + */ + bool (*enable_signaling)(struct dma_fence *fence); + + /** + * @signaled: + * + * Peek whether the fence is signaled, as a fastpath optimization for + * e.g. dma_fence_wait() or dma_fence_add_callback(). Note that this + * callback does not need to make any guarantees beyond that a fence + * once indicates as signalled must always return true from this + * callback. This callback may return false even if the fence has + * completed already, in this case information hasn't propogated through + * the system yet. See also dma_fence_is_signaled(). + * + * May set &dma_fence.error if returning true. + * + * This callback is optional. + */ + bool (*signaled)(struct dma_fence *fence); + + /** + * @wait: + * + * Custom wait implementation, defaults to dma_fence_default_wait() if + * not set. + * + * The dma_fence_default_wait implementation should work for any fence, + * as long as @enable_signaling works correctly. This hook allows + * drivers to have an optimized version for the case where a process + * context is already available, e.g. if @enable_signaling for the + * general case needs to set up a worker thread. + * + * 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. + * + * This callback is optional. + */ + signed long (*wait)(struct dma_fence *fence, + bool intr, signed long timeout); + + /** + * @release: + * + * Called on destruction of fence to release additional resources. + * Can be called from irq context. This callback is optional. If it is + * NULL, then dma_fence_free() is instead called as the default + * implementation. + */ + void (*release)(struct dma_fence *fence); + + /** + * @fence_value_str: + * + * Callback to fill in free-form debug info specific to this fence, like + * the sequence number. + * + * This callback is optional. + */ + void (*fence_value_str)(struct dma_fence *fence, char *str, int size); + + /** + * @timeline_value_str: + * + * Fills in the current value of the timeline as a string, like the + * sequence number. Note that the specific fence passed to this function + * should not matter, drivers should only use it to look up the + * corresponding timeline structures. + */ + void (*timeline_value_str)(struct dma_fence *fence, + char *str, int size); +}; + +#endif /* __LINUX_DMA_FENCE_TYPES_H */ diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h index bea1d05cf51e..1c8dd1fbafae 100644 --- a/include/linux/dma-fence.h +++ b/include/linux/dma-fence.h @@ -13,6 +13,7 @@ #ifndef __LINUX_DMA_FENCE_H #define __LINUX_DMA_FENCE_H +#include <linux/dma-fence-types.h> #include <linux/err.h> #include <linux/wait.h> #include <linux/list.h> @@ -22,233 +23,6 @@ #include <linux/printk.h> #include <linux/rcupdate.h> -struct dma_fence; -struct dma_fence_ops; -struct dma_fence_cb; - -/** - * struct dma_fence - software synchronization primitive - * @refcount: refcount for this fence - * @ops: dma_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 - * dma_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 DMA_FENCE_FLAG_* defined below - * @timestamp: Timestamp when the fence was signaled. - * @error: Optional, only valid if < 0, must be set before calling - * dma_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. - * - * DMA_FENCE_FLAG_SIGNALED_BIT - fence is already signaled - * DMA_FENCE_FLAG_TIMESTAMP_BIT - timestamp recorded for fence signaling - * DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT - enable_signaling might have been called - * DMA_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 dma_fence_signal was called right - * before this bit was set, it would have been able to set the - * DMA_FENCE_FLAG_SIGNALED_BIT, before enable_signaling was called. - * Adding a check for DMA_FENCE_FLAG_SIGNALED_BIT after setting - * DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT closes this race, and makes sure that - * after dma_fence_signal was called, any enable_signaling call will have either - * been completed, or never called at all. - */ -struct dma_fence { - struct kref refcount; - const struct dma_fence_ops *ops; - /* We clear the callback list on kref_put so that by the time we - * release the fence it is unused. No one should be adding to the cb_list - * that they don't themselves hold a reference for. - */ - union { - struct rcu_head rcu; - struct list_head cb_list; - }; - spinlock_t *lock; - u64 context; - u64 seqno; - unsigned long flags; - ktime_t timestamp; - int error; -}; - -enum dma_fence_flag_bits { - DMA_FENCE_FLAG_SIGNALED_BIT, - DMA_FENCE_FLAG_TIMESTAMP_BIT, - DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, - DMA_FENCE_FLAG_USER_BITS, /* must always be last member */ -}; - -typedef void (*dma_fence_func_t)(struct dma_fence *fence, - struct dma_fence_cb *cb); - -/** - * struct dma_fence_cb - callback for dma_fence_add_callback() - * @node: used by dma_fence_add_callback() to append this struct to fence::cb_list - * @func: dma_fence_func_t to call - * - * This struct will be initialized by dma_fence_add_callback(), additional - * data can be passed along by embedding dma_fence_cb in another struct. - */ -struct dma_fence_cb { - struct list_head node; - dma_fence_func_t func; -}; - -/** - * struct dma_fence_ops - operations implemented for fence - * - */ -struct dma_fence_ops { - /** - * @use_64bit_seqno: - * - * True if this dma_fence implementation uses 64bit seqno, false - * otherwise. - */ - bool use_64bit_seqno; - - /** - * @get_driver_name: - * - * Returns the driver name. This is a callback to allow drivers to - * compute the name at runtime, without having it to store permanently - * for each fence, or build a cache of some sort. - * - * This callback is mandatory. - */ - const char * (*get_driver_name)(struct dma_fence *fence); - - /** - * @get_timeline_name: - * - * Return the name of the context this fence belongs to. This is a - * callback to allow drivers to compute the name at runtime, without - * having it to store permanently for each fence, or build a cache of - * some sort. - * - * This callback is mandatory. - */ - const char * (*get_timeline_name)(struct dma_fence *fence); - - /** - * @enable_signaling: - * - * Enable software signaling of fence. - * - * For fence implementations that have the capability for hw->hw - * signaling, they can implement this op to enable the necessary - * interrupts, or insert commands into cmdstream, etc, to avoid these - * costly operations for the common case where only hw->hw - * synchronization is required. This is called in the first - * dma_fence_wait() or dma_fence_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 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. - * - * &dma_fence.error may be set in enable_signaling, but only when false - * is returned. - * - * Since many implementations can call dma_fence_signal() even when before - * @enable_signaling has been called there's a race window, where the - * dma_fence_signal() might result in the final fence reference being - * released and its memory freed. To avoid this, implementations of this - * callback should grab their own reference using dma_fence_get(), to be - * released when the fence is signalled (through e.g. the interrupt - * handler). - * - * This callback is optional. If this callback is not present, then the - * driver must always have signaling enabled. - */ - bool (*enable_signaling)(struct dma_fence *fence); - - /** - * @signaled: - * - * Peek whether the fence is signaled, as a fastpath optimization for - * e.g. dma_fence_wait() or dma_fence_add_callback(). Note that this - * callback does not need to make any guarantees beyond that a fence - * once indicates as signalled must always return true from this - * callback. This callback may return false even if the fence has - * completed already, in this case information hasn't propogated throug - * the system yet. See also dma_fence_is_signaled(). - * - * May set &dma_fence.error if returning true. - * - * This callback is optional. - */ - bool (*signaled)(struct dma_fence *fence); - - /** - * @wait: - * - * Custom wait implementation, defaults to dma_fence_default_wait() if - * not set. - * - * The dma_fence_default_wait implementation should work for any fence, as long - * as @enable_signaling works correctly. This hook allows drivers to - * have an optimized version for the case where a process context is - * already available, e.g. if @enable_signaling for the general case - * needs to set up a worker thread. - * - * 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. - * - * This callback is optional. - */ - signed long (*wait)(struct dma_fence *fence, - bool intr, signed long timeout); - - /** - * @release: - * - * Called on destruction of fence to release additional resources. - * Can be called from irq context. This callback is optional. If it is - * NULL, then dma_fence_free() is instead called as the default - * implementation. - */ - void (*release)(struct dma_fence *fence); - - /** - * @fence_value_str: - * - * Callback to fill in free-form debug info specific to this fence, like - * the sequence number. - * - * This callback is optional. - */ - void (*fence_value_str)(struct dma_fence *fence, char *str, int size); - - /** - * @timeline_value_str: - * - * Fills in the current value of the timeline as a string, like the - * sequence number. Note that the specific fence passed to this function - * should not matter, drivers should only use it to look up the - * corresponding timeline structures. - */ - void (*timeline_value_str)(struct dma_fence *fence, - char *str, int size); -}; - void dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops, spinlock_t *lock, u64 context, u64 seqno); -- 2.23.0.rc1 _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel