[PATCH 01/13] drm/i915: Add a sw fence for collecting up dma fences
Chris Wilson
chris at chris-wilson.co.uk
Wed Aug 24 14:44:29 UTC 2016
This is really a core kernel struct in disguise until we can finally
place it in kernel/
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
drivers/gpu/drm/i915/Makefile | 1 +
drivers/gpu/drm/i915/i915_sw_fence.c | 329 +++++++++++++++++++++++++++++++++++
drivers/gpu/drm/i915/i915_sw_fence.h | 56 ++++++
3 files changed, 386 insertions(+)
create mode 100644 drivers/gpu/drm/i915/i915_sw_fence.c
create mode 100644 drivers/gpu/drm/i915/i915_sw_fence.h
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index a7da24640e88..a998c2bce70a 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -16,6 +16,7 @@ i915-y := i915_drv.o \
i915_params.o \
i915_pci.o \
i915_suspend.o \
+ i915_sw_fence.o \
i915_sysfs.o \
intel_csr.o \
intel_device_info.o \
diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c
new file mode 100644
index 000000000000..170d3bf70953
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_sw_fence.c
@@ -0,0 +1,329 @@
+/*
+ * (C) Copyright 2016 Intel Corporation
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ */
+
+#include <linux/slab.h>
+#include <linux/fence.h>
+#include <linux/reservation.h>
+
+#include "i915_sw_fence.h"
+
+static DEFINE_SPINLOCK(i915_sw_fence_lock);
+
+static int __i915_sw_fence_notify(struct i915_sw_fence *fence)
+{
+ i915_sw_fence_notify_t fn;
+
+ fn = (i915_sw_fence_notify_t)(fence->flags & I915_SW_FENCE_MASK);
+ return fn(fence);
+}
+
+static void i915_sw_fence_free(struct kref *kref)
+{
+ struct i915_sw_fence *fence = container_of(kref, typeof(*fence), kref);
+
+ WARN_ON(atomic_read(&fence->pending) > 0);
+
+ if (fence->flags & I915_SW_FENCE_MASK)
+ WARN_ON(__i915_sw_fence_notify(fence) != NOTIFY_DONE);
+ else
+ kfree(fence);
+}
+
+static void i915_sw_fence_put(struct i915_sw_fence *fence)
+{
+ kref_put(&fence->kref, i915_sw_fence_free);
+}
+
+static struct i915_sw_fence *i915_sw_fence_get(struct i915_sw_fence *fence)
+{
+ kref_get(&fence->kref);
+ return fence;
+}
+
+static void __i915_sw_fence_wake_up_all(struct i915_sw_fence *fence,
+ struct list_head *continuation)
+{
+ wait_queue_head_t *x = &fence->wait;
+ unsigned long flags;
+
+ atomic_dec(&fence->pending);
+
+ /*
+ * To prevent unbounded recursion as we traverse the graph of i915_sw_fences,
+ * we move the task_list from this the next ready fence to the tail of
+ * the original fence's task_list (and so added to the list to be
+ * woken).
+ */
+ smp_mb__before_spinlock();
+ if (!list_empty_careful(&x->task_list)) {
+ spin_lock_irqsave_nested(&x->lock, flags, 1 + !!continuation);
+ if (continuation) {
+ list_splice_tail_init(&x->task_list, continuation);
+ } else {
+ LIST_HEAD(extra);
+
+ do {
+ __wake_up_locked_key(x, TASK_NORMAL, &extra);
+
+ if (list_empty(&extra))
+ break;
+
+ list_splice_tail_init(&extra, &x->task_list);
+ } while (1);
+ }
+ spin_unlock_irqrestore(&x->lock, flags);
+ }
+}
+
+static void __i915_sw_fence_complete(struct i915_sw_fence *fence,
+ struct list_head *continuation)
+{
+ if (!atomic_dec_and_test(&fence->pending))
+ return;
+
+ if (fence->flags & I915_SW_FENCE_MASK &&
+ __i915_sw_fence_notify(fence) != NOTIFY_DONE)
+ return;
+
+ __i915_sw_fence_wake_up_all(fence, continuation);
+}
+
+static void i915_sw_fence_complete(struct i915_sw_fence *fence)
+{
+ if (WARN_ON(i915_sw_fence_done(fence)))
+ return;
+
+ __i915_sw_fence_complete(fence, NULL);
+}
+
+static void i915_sw_fence_await(struct i915_sw_fence *fence)
+{
+ WARN_ON(atomic_inc_return(&fence->pending) <= 1);
+}
+
+static void i915_sw_fence_wait(struct i915_sw_fence *fence)
+{
+ wait_event(fence->wait, i915_sw_fence_done(fence));
+}
+
+void i915_sw_fence_init(struct i915_sw_fence *fence, i915_sw_fence_notify_t fn)
+{
+ BUG_ON((unsigned long)fn & ~I915_SW_FENCE_MASK);
+
+ init_waitqueue_head(&fence->wait);
+ kref_init(&fence->kref);
+ atomic_set(&fence->pending, 1);
+ fence->flags = (unsigned long)fn;
+}
+
+void i915_sw_fence_commit(struct i915_sw_fence *fence)
+{
+ i915_sw_fence_complete(fence);
+ i915_sw_fence_put(fence);
+}
+
+static int i915_sw_fence_wake(wait_queue_t *wq, unsigned mode, int flags, void *key)
+{
+ list_del(&wq->task_list);
+ __i915_sw_fence_complete(wq->private, key);
+ i915_sw_fence_put(wq->private);
+ kfree(wq);
+ return 0;
+}
+
+static bool __i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
+ const struct i915_sw_fence * const signaler)
+{
+ wait_queue_t *wq;
+
+ if (__test_and_set_bit(I915_SW_FENCE_CHECKED_BIT, &fence->flags))
+ return false;
+
+ if (fence == signaler)
+ return true;
+
+ list_for_each_entry(wq, &fence->wait.task_list, task_list) {
+ if (wq->func != i915_sw_fence_wake)
+ continue;
+
+ if (__i915_sw_fence_check_if_after(wq->private, signaler))
+ return true;
+ }
+
+ return false;
+}
+
+static void __i915_sw_fence_clear_checked_bit(struct i915_sw_fence *fence)
+{
+ wait_queue_t *wq;
+
+ if (!__test_and_clear_bit(I915_SW_FENCE_CHECKED_BIT, &fence->flags))
+ return;
+
+ list_for_each_entry(wq, &fence->wait.task_list, task_list) {
+ if (wq->func != i915_sw_fence_wake)
+ continue;
+
+ __i915_sw_fence_clear_checked_bit(wq->private);
+ }
+}
+
+static bool i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
+ const struct i915_sw_fence * const signaler)
+{
+ unsigned long flags;
+ bool err;
+
+ if (!IS_ENABLED(CONFIG_I915_SW_FENCE_CHECK_DAG))
+ return false;
+
+ spin_lock_irqsave(&i915_sw_fence_lock, flags);
+ err = __i915_sw_fence_check_if_after(fence, signaler);
+ __i915_sw_fence_clear_checked_bit(fence);
+ spin_unlock_irqrestore(&i915_sw_fence_lock, flags);
+
+ return err;
+}
+
+static wait_queue_t *__i915_sw_fence_create_wq(struct i915_sw_fence *fence, gfp_t gfp)
+{
+ wait_queue_t *wq;
+
+ wq = kmalloc(sizeof(*wq), gfp);
+ if (unlikely(!wq))
+ return NULL;
+
+ INIT_LIST_HEAD(&wq->task_list);
+ wq->flags = 0;
+ wq->func = i915_sw_fence_wake;
+ wq->private = i915_sw_fence_get(fence);
+
+ i915_sw_fence_await(fence);
+
+ return wq;
+}
+
+int i915_sw_fence_await_i915_sw_fence(struct i915_sw_fence *fence,
+ struct i915_sw_fence *signaler,
+ gfp_t gfp)
+{
+ wait_queue_t *wq;
+ unsigned long flags;
+ int pending;
+
+ if (i915_sw_fence_done(signaler))
+ return 0;
+
+ /* The dependency graph must be acyclic. */
+ if (unlikely(i915_sw_fence_check_if_after(fence, signaler)))
+ return -EINVAL;
+
+ wq = __i915_sw_fence_create_wq(fence, gfp);
+ if (unlikely(!wq)) {
+ if (!gfpflags_allow_blocking(gfp))
+ return -ENOMEM;
+
+ i915_sw_fence_wait(signaler);
+ return 0;
+ }
+
+ spin_lock_irqsave(&signaler->wait.lock, flags);
+ if (likely(!i915_sw_fence_done(signaler))) {
+ __add_wait_queue_tail(&signaler->wait, wq);
+ pending = 1;
+ } else {
+ i915_sw_fence_wake(wq, 0, 0, NULL);
+ pending = 0;
+ }
+ spin_unlock_irqrestore(&signaler->wait.lock, flags);
+
+ return pending;
+}
+
+struct dma_fence_cb {
+ struct fence_cb base;
+ struct i915_sw_fence *fence;
+};
+
+static void dma_i915_sw_fence_wake(struct fence *dma, struct fence_cb *data)
+{
+ struct dma_fence_cb *cb = container_of(data, typeof(*cb), base);
+
+ i915_sw_fence_commit(cb->fence);
+ kfree(cb);
+}
+
+int i915_sw_fence_await_dma_fence(struct i915_sw_fence *fence,
+ struct fence *dma, gfp_t gfp)
+{
+ struct dma_fence_cb *cb;
+ int ret;
+
+ if (fence_is_signaled(dma))
+ return 0;
+
+ cb = kmalloc(sizeof(*cb), gfp);
+ if (!cb) {
+ if (!gfpflags_allow_blocking(gfp))
+ return -ENOMEM;
+
+ return fence_wait(dma, false);
+ }
+
+ cb->fence = i915_sw_fence_get(fence);
+ i915_sw_fence_await(fence);
+
+ ret = fence_add_callback(dma, &cb->base, dma_i915_sw_fence_wake);
+ if (ret == 0) {
+ ret = 1;
+ } else {
+ dma_i915_sw_fence_wake(dma, &cb->base);
+ if (ret == -ENOENT) /* fence already signaled */
+ ret = 0;
+ }
+
+ return ret;
+}
+
+int i915_sw_fence_await_reservation(struct i915_sw_fence *fence,
+ struct reservation_object *resv,
+ const struct fence_ops *exclude,
+ bool write,
+ gfp_t gfp)
+{
+ struct fence *excl, **shared;
+ unsigned int count, i;
+ int ret;
+
+ ret = reservation_object_get_fences_rcu(resv, &excl, &count, &shared);
+ if (ret)
+ return ret;
+
+ if (write) {
+ for (i = 0; i < count; i++) {
+ if (shared[i]->ops == exclude)
+ continue;
+
+ ret |= i915_sw_fence_await_dma_fence(fence, shared[i], gfp);
+ if (ret < 0)
+ goto out;
+ }
+ }
+
+ if (excl && excl->ops != exclude)
+ ret |= i915_sw_fence_await_dma_fence(fence, excl, gfp);
+
+out:
+ fence_put(excl);
+ for (i = 0; i < count; i++)
+ fence_put(shared[i]);
+ kfree(shared);
+
+ return ret;
+}
diff --git a/drivers/gpu/drm/i915/i915_sw_fence.h b/drivers/gpu/drm/i915/i915_sw_fence.h
new file mode 100644
index 000000000000..45387653caab
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_sw_fence.h
@@ -0,0 +1,56 @@
+/*
+ * i915_sw_fence.h - library routines for N:M synchronisation points
+ *
+ * Copyright (C) 2016 Intel Corporation
+ *
+ * This file is released under the GPLv2.
+ *
+ */
+
+#ifndef _I915_SW_FENCE_H_
+#define _I915_SW_FENCE_H_
+
+#include <linux/gfp.h>
+#include <linux/kref.h>
+#include <linux/notifier.h> /* for NOTIFY_DONE */
+#include <linux/wait.h>
+
+struct completion;
+struct fence;
+struct fence_ops;
+struct reservation_object;
+
+struct i915_sw_fence {
+ wait_queue_head_t wait;
+ unsigned long flags;
+ struct kref kref;
+ atomic_t pending;
+};
+
+#define I915_SW_FENCE_CHECKED_BIT 0 /* used internally for DAG checking */
+#define I915_SW_FENCE_PRIVATE_BIT 1 /* available for use by owner */
+#define I915_SW_FENCE_MASK (~3)
+
+typedef int (*i915_sw_fence_notify_t)(struct i915_sw_fence *);
+#define __i915_sw_fence_call __aligned(4)
+
+void i915_sw_fence_init(struct i915_sw_fence *fence, i915_sw_fence_notify_t fn);
+void i915_sw_fence_commit(struct i915_sw_fence *fence);
+
+int i915_sw_fence_await_i915_sw_fence(struct i915_sw_fence *fence,
+ struct i915_sw_fence *after,
+ gfp_t gfp);
+int i915_sw_fence_await_dma_fence(struct i915_sw_fence *fence,
+ struct fence *dma, gfp_t gfp);
+int i915_sw_fence_await_reservation(struct i915_sw_fence *fence,
+ struct reservation_object *resv,
+ const struct fence_ops *exclude,
+ bool write,
+ gfp_t gfp);
+
+static inline bool i915_sw_fence_done(const struct i915_sw_fence *fence)
+{
+ return atomic_read(&fence->pending) < 0;
+}
+
+#endif /* _I915_SW_FENCE_H_ */
--
2.9.3
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