[3/4] dma-fence: Refactor signaling for manual invocation

Message ID	20190810153430.30636-3-chris@chris-wilson.co.uk (mailing list archive)
State	New, archived
Headers	show Return-Path: <dri-devel-bounces@lists.freedesktop.org> From: Chris Wilson <chris@chris-wilson.co.uk> To: dri-devel@lists.freedesktop.org Subject: [PATCH 3/4] dma-fence: Refactor signaling for manual invocation Date: Sat, 10 Aug 2019 16:34:29 +0100 Message-Id: <20190810153430.30636-3-chris@chris-wilson.co.uk> In-Reply-To: <20190810153430.30636-1-chris@chris-wilson.co.uk> References: <20190810153430.30636-1-chris@chris-wilson.co.uk> MIME-Version: 1.0 Precedence: list Cc: intel-gfx@lists.freedesktop.org, Tvrtko Ursulin <tvrtko.ursulin@intel.com>, christian.koenig@amd.com Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" <dri-devel-bounces@lists.freedesktop.org>
Series	[1/4] dma-fence: Propagate errors to dma-fence-array container \| expand [1/4] dma-fence: Propagate errors to dma-fence-array container [2/4] dma-fence: Report the composite sync_file status [3/4] dma-fence: Refactor signaling for manual invocation [4/4] dma-fence: Always execute signal callbacks

Am 10.08.19 um 17:34 schrieb Chris Wilson: > 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 <chris@chris-wilson.co.uk> > Cc: Tvrtko Ursulin <tvrtko.ursulin@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 +---------------- Mhm, I don't really see the value in creating more header files. Especially I'm pretty sure that the types should stay in dma-fence.h Christian. > 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 <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. > + */ > + > +#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 <robdclark@gmail.com> > + * Maarten Lankhorst <maarten.lankhorst@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 <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_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); >

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 <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. + */ + +#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 <robdclark@gmail.com> + * Maarten Lankhorst <maarten.lankhorst@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 <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_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);

[3/4] dma-fence: Refactor signaling for manual invocation

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