From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
struct fence_collection inherits from struct fence and carries a
collection of fences that needs to be waited together.
It is useful to translate a sync_file to a fence to remove the complexity
of dealing with sync_files on DRM drivers. So even if there are many
fences in the sync_file that needs to waited for a commit to happen,
they all get added to the fence_collection and passed for DRM use as
a standard struct fence.
That means that no changes needed to any driver besides supporting fences.
fence_collection's fence doesn't belong to any timeline context, so
fence_is_later() and fence_later() are not meant to be called with
fence_collections fences.
v2: Comments by Daniel Vetter:
- merge fence_collection_init() and fence_collection_add()
- only add callbacks at ->enable_signalling()
- remove fence_collection_put()
- check for type on to_fence_collection()
- adjust fence_is_later() and fence_later() to WARN_ON() if they
are used with collection fences.
v3: - Initialize fence_cb.node at fence init.
Comments by Chris Wilson:
- return "unbound" on fence_collection_get_timeline_name()
- don't stop adding callbacks if one fails
- remove redundant !! on fence_collection_enable_signaling()
- remove redundant () on fence_collection_signaled
- use fence_default_wait() instead
v4 (chk): Rework, simplification and cleanup:
- Drop FENCE_NO_CONTEXT handling, always allocate a context.
- Rename to fence_array.
- Return fixed driver name.
- Register only one callback at a time.
- Document that create function takes ownership of array.
v5 (chk): More work and fixes:
- Avoid deadlocks by adding all callbacks at once again.
- Stop trying to remove the callbacks.
- Provide context and sequence number for the array fence.
Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
---
drivers/dma-buf/Makefile | 2 +-
drivers/dma-buf/fence-array.c | 127 ++++++++++++++++++++++++++++++++++++++++++
include/linux/fence-array.h | 72 ++++++++++++++++++++++++
3 files changed, 200 insertions(+), 1 deletion(-)
create mode 100644 drivers/dma-buf/fence-array.c
create mode 100644 include/linux/fence-array.h
diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile
index 57a675f..85f6928 100644
--- a/drivers/dma-buf/Makefile
+++ b/drivers/dma-buf/Makefile
@@ -1 +1 @@
-obj-y := dma-buf.o fence.o reservation.o seqno-fence.o
+obj-y := dma-buf.o fence.o reservation.o seqno-fence.o fence-array.o
diff --git a/drivers/dma-buf/fence-array.c b/drivers/dma-buf/fence-array.c
new file mode 100644
index 0000000..bbcf79f
--- /dev/null
+++ b/drivers/dma-buf/fence-array.c
@@ -0,0 +1,127 @@
+/*
+ * fence-array: aggregate fences to be waited together
+ *
+ * Copyright (C) 2016 Collabora Ltd
+ * Copyright (C) 2016 Advanced Micro Devices, Inc.
+ * Authors:
+ * Gustavo Padovan <gustavo@xxxxxxxxxxx>
+ * Christian König <christian.koenig@xxxxxxx>
+ *
+ * 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/export.h>
+#include <linux/slab.h>
+#include <linux/fence-array.h>
+
+static void fence_array_cb_func(struct fence *f, struct fence_cb *cb);
+
+static const char *fence_array_get_driver_name(struct fence *fence)
+{
+ return "fence_array";
+}
+
+static const char *fence_array_get_timeline_name(struct fence *fence)
+{
+ return "unbound";
+}
+
+static void fence_array_cb_func(struct fence *f, struct fence_cb *cb)
+{
+ struct fence_array_cb *array_cb =
+ container_of(cb, struct fence_array_cb, cb);
+ struct fence_array *array = array_cb->array;
+
+ if (atomic_dec_and_test(&array->num_pending))
+ fence_signal(&array->base);
+}
+
+static bool fence_array_enable_signaling(struct fence *fence)
+{
+ struct fence_array *array = to_fence_array(fence);
+ struct fence_array_cb *cb = (void *)(&array[1]);
+ unsigned i;
+
+ for (i = 0; i < array->num_fences; ++i) {
+ cb[i].array = array;
+ if (!fence_add_callback(array->fences[i], &cb[i].cb,
+ fence_array_cb_func))
+ if (atomic_dec_and_test(&array->num_pending))
+ return false;
+ }
+
+ return true;
+}
+
+static bool fence_array_signaled(struct fence *fence)
+{
+ struct fence_array *array = to_fence_array(fence);
+
+ return atomic_read(&array->num_pending) == 0;
+}
+
+static void fence_array_release(struct fence *fence)
+{
+ struct fence_array *array = to_fence_array(fence);
+ unsigned i;
+
+ for (i = 0; i < array->num_fences; ++i)
+ fence_put(array->fences[i]);
+
+ kfree(array->fences);
+ fence_free(fence);
+}
+
+const struct fence_ops fence_array_ops = {
+ .get_driver_name = fence_array_get_driver_name,
+ .get_timeline_name = fence_array_get_timeline_name,
+ .enable_signaling = fence_array_enable_signaling,
+ .signaled = fence_array_signaled,
+ .wait = fence_default_wait,
+ .release = fence_array_release,
+};
+
+/**
+ * fence_array_create - Create a custom fence array
+ * @num_fences: [in] number of fences to add in the array
+ * @fences: [in] array containing the fences
+ * @context: [in] fence context to use
+ * @seqno: [in] sequence number to use
+ *
+ * Allocate a fence_array object and initialize the base fence with fence_init().
+ * In case of error it returns NULL.
+ *
+ * The caller should allocte the fences array with num_fences size
+ * and fill it with the fences it wants to add to the object. Ownership of this
+ * array is take and fence_put() is used on each fence on release.
+ */
+struct fence_array *fence_array_create(int num_fences, struct fence **fences,
+ u64 context, unsigned seqno)
+{
+ struct fence_array *array;
+ size_t size = sizeof(*array);
+
+ /* Allocate the callback structures behind the array. */
+ size += num_fences * sizeof(struct fence_array_cb);
+ array = kzalloc(size, GFP_KERNEL);
+ if (!array)
+ return NULL;
+
+ spin_lock_init(&array->lock);
+ fence_init(&array->base, &fence_array_ops, &array->lock,
+ context, seqno);
+
+ array->num_fences = num_fences;
+ atomic_set(&array->num_pending, num_fences);
+ array->fences = fences;
+
+ return array;
+}
+EXPORT_SYMBOL(fence_array_create);
diff --git a/include/linux/fence-array.h b/include/linux/fence-array.h
new file mode 100644
index 0000000..593ab98
--- /dev/null
+++ b/include/linux/fence-array.h
@@ -0,0 +1,72 @@
+/*
+ * fence-array: aggregates fence to be waited together
+ *
+ * Copyright (C) 2016 Collabora Ltd
+ * Copyright (C) 2016 Advanced Micro Devices, Inc.
+ * Authors:
+ * Gustavo Padovan <gustavo@xxxxxxxxxxx>
+ * Christian König <christian.koenig@xxxxxxx>
+ *
+ * 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_FENCE_ARRAY_H
+#define __LINUX_FENCE_ARRAY_H
+
+#include <linux/fence.h>
+
+/**
+ * struct fence_array_cb - callback helper for fence array
+ * @cb: fence callback structure for signaling
+ * @array: reference to the parent fence array object
+ */
+struct fence_array_cb {
+ struct fence_cb cb;
+ struct fence_array *array;
+};
+
+/**
+ * struct fence_array - fence to represent an array of fences
+ * @base: fence base class
+ * @lock: spinlock for fence handling
+ * @num_fences: number of fences in the array
+ * @num_pending: fences in the array still pending
+ * @fences: array of the fences
+ */
+struct fence_array {
+ struct fence base;
+
+ spinlock_t lock;
+ unsigned num_fences;
+ atomic_t num_pending;
+ struct fence **fences;
+};
+
+extern const struct fence_ops fence_array_ops;
+
+/**
+ * to_fence_array - cast a fence to a fence_array
+ * @fence: fence to cast to a fence_array
+ *
+ * Returns NULL if the fence is not a fence_array,
+ * or the fence_array otherwise.
+ */
+static inline struct fence_array *to_fence_array(struct fence *fence)
+{
+ if (fence->ops != &fence_array_ops)
+ return NULL;
+
+ return container_of(fence, struct fence_array, base);
+}
+
+struct fence_array *fence_array_create(int num_fences, struct fence **fences,
+ u64 context, unsigned seqno);
+
+#endif /* __LINUX_FENCE_ARRAY_H */
--
2.5.0
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