From: Gustavo Padovan gustavo.padovan@collabora.co.uk
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.
Signed-off-by: Gustavo Padovan gustavo.padovan@collabora.co.uk --- drivers/dma-buf/Makefile | 2 +- drivers/dma-buf/fence-collection.c | 159 +++++++++++++++++++++++++++++++++++++ drivers/dma-buf/fence.c | 2 +- include/linux/fence-collection.h | 73 +++++++++++++++++ include/linux/fence.h | 9 +++ 5 files changed, 243 insertions(+), 2 deletions(-) create mode 100644 drivers/dma-buf/fence-collection.c create mode 100644 include/linux/fence-collection.h
diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile index 4a424ec..52f818f 100644 --- a/drivers/dma-buf/Makefile +++ b/drivers/dma-buf/Makefile @@ -1,2 +1,2 @@ -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-collection.o obj-$(CONFIG_SYNC_FILE) += sync_file.o diff --git a/drivers/dma-buf/fence-collection.c b/drivers/dma-buf/fence-collection.c new file mode 100644 index 0000000..88872e5 --- /dev/null +++ b/drivers/dma-buf/fence-collection.c @@ -0,0 +1,159 @@ +/* + * fence-collection: aggregate fences to be waited together + * + * Copyright (C) 2016 Collabora Ltd + * Authors: + * Gustavo Padovan gustavo@padovan.org + * + * 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-collection.h> + +static const char *fence_collection_get_driver_name(struct fence *fence) +{ + struct fence_collection *collection = to_fence_collection(fence); + struct fence *f = collection->fences[0].fence; + + return f->ops->get_driver_name(fence); +} + +static const char *fence_collection_get_timeline_name(struct fence *fence) +{ + return "no context"; +} + +static void collection_check_cb_func(struct fence *fence, struct fence_cb *cb) +{ + struct fence_collection_cb *f_cb; + struct fence_collection *collection; + + f_cb = container_of(cb, struct fence_collection_cb, cb); + collection = f_cb->collection; + + if (atomic_dec_and_test(&collection->num_pending_fences)) + fence_signal(&collection->base); +} + +static bool fence_collection_enable_signaling(struct fence *fence) +{ + struct fence_collection *collection = to_fence_collection(fence); + int i; + + for (i = 0 ; i < collection->num_fences ; i++) { + if (fence_add_callback(collection->fences[i].fence, + &collection->fences[i].cb, + collection_check_cb_func)) { + atomic_dec(&collection->num_pending_fences); + return false; + } + } + + return !!atomic_read(&collection->num_pending_fences); +} + +static bool fence_collection_signaled(struct fence *fence) +{ + struct fence_collection *collection = to_fence_collection(fence); + + return (atomic_read(&collection->num_pending_fences) == 0); +} + +static void fence_collection_release(struct fence *fence) +{ + struct fence_collection *collection = to_fence_collection(fence); + int i; + + for (i = 0 ; i < collection->num_fences ; i++) + fence_put(collection->fences[i].fence); + + kfree(collection->fences); + fence_free(fence); +} + +static signed long fence_collection_wait(struct fence *fence, bool intr, + signed long timeout) +{ + struct fence_collection *collection = to_fence_collection(fence); + int i; + + if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) + return timeout; + + fence_enable_sw_signaling(fence); + + for (i = 0 ; i < collection->num_fences ; i++) { + if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) + return timeout; + + timeout = fence_wait(collection->fences[i].fence, intr); + if (timeout < 0) + return timeout; + } + + return timeout; +} + +const struct fence_ops fence_collection_ops = { + .get_driver_name = fence_collection_get_driver_name, + .get_timeline_name = fence_collection_get_timeline_name, + .enable_signaling = fence_collection_enable_signaling, + .signaled = fence_collection_signaled, + .wait = fence_collection_wait, + .release = fence_collection_release, +}; + +/** + * fence_collection_create - Create a custom fence collection + * is signaled + * @num_fences: [in] number of fences to add in the collection + * @cb: [in] cb array containing the fences for the collection + * + * Allocate a fence_collection and initialize the base fence with fence_init() + * and FENCE_NO_CONTEXT. It also inits all fence_collections specific fields + * and return the created fence_collection. In case of error it returns NULL. + * + * The caller should allocte the fence_collection_cb array with num_fences size + * and fill the fence fields with all the fences it wants to add to the + * collection. + * + * Collections have no context, thus fence_later() and fence_is_later() shall + * not be used with fence_collection. + * + * fence_put() on the base fence should be used to release the collection. + */ +struct fence_collection *fence_collection_create(int num_fences, + struct fence_collection_cb *cb) +{ + struct fence_collection *collection; + int i; + + collection = kzalloc(sizeof(*collection), GFP_KERNEL); + if (!collection) + return NULL; + + spin_lock_init(&collection->lock); + fence_init(&collection->base, &fence_collection_ops, &collection->lock, + FENCE_NO_CONTEXT, 0); + + collection->fences = cb; + collection->num_fences = num_fences; + atomic_set(&collection->num_pending_fences, num_fences); + + for (i = 0 ; i < collection->num_fences ; i++) { + fence_get(collection->fences[i].fence); + collection->fences[i].collection = collection; + } + + return collection; +} +EXPORT_SYMBOL(fence_collection_create); diff --git a/drivers/dma-buf/fence.c b/drivers/dma-buf/fence.c index 7b05dbe..486e95c 100644 --- a/drivers/dma-buf/fence.c +++ b/drivers/dma-buf/fence.c @@ -35,7 +35,7 @@ EXPORT_TRACEPOINT_SYMBOL(fence_emit); * context or not. One device can have multiple separate contexts, * and they're used if some engine can run independently of another. */ -static atomic_t fence_context_counter = ATOMIC_INIT(0); +static atomic_t fence_context_counter = ATOMIC_INIT(1);
/** * fence_context_alloc - allocate an array of fence contexts diff --git a/include/linux/fence-collection.h b/include/linux/fence-collection.h new file mode 100644 index 0000000..4087622 --- /dev/null +++ b/include/linux/fence-collection.h @@ -0,0 +1,73 @@ +/* + * fence-collection: aggregates fence to be waited together + * + * Copyright (C) 2016 Collabora Ltd + * Authors: + * Gustavo Padovan gustavo@padovan.org + * + * 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_COLLECTION_H +#define __LINUX_FENCE_COLLECTION_H + +#include <linux/fence.h> + +/** + * struct fence_collection_cb - callback for fence_add_callback + * @cb: the base fence_cb object + * @fence: fence we are storing in the collection + * @collection: collection the fence belongs to + * + * This struct is at the same time the storage for the fences in the + * collection and the struct we pass to fence_add_callback() + */ +struct fence_collection_cb { + struct fence_cb cb; + struct fence *fence; + struct fence_collection *collection; +}; + +/** + * struct fence_collection - fence to represent a collection of fences + * @base: fence base class + * @lock: spinlock for fence handling + * @num_pending_fences: fences in the collection not signaled yet + * @num_fences: number of fences in the collection + * @fences: ponteir to fence_collection_cb with data about the fences + */ +struct fence_collection { + struct fence base; + + spinlock_t lock; + atomic_t num_pending_fences; + int num_fences; + struct fence_collection_cb *fences; +}; + +extern const struct fence_ops fence_collection_ops; + +/** + * to_fence_collection - cast a fence to a fence_collection + * @fence: fence to cast to a fence_collection + * + * Returns NULL if the fence is not a fence_collection, + * or the fence_collection otherwise. + */ +static inline struct fence_collection *to_fence_collection(struct fence *fence) +{ + if (fence->ops != &fence_collection_ops) + return NULL; + return container_of(fence, struct fence_collection, base); +} + +struct fence_collection *fence_collection_create(int num_fences, + struct fence_collection_cb *cb); +#endif /* __LINUX_FENCE_COLLECTION_H */ diff --git a/include/linux/fence.h b/include/linux/fence.h index 5aa95eb..184ce79 100644 --- a/include/linux/fence.h +++ b/include/linux/fence.h @@ -30,6 +30,9 @@ #include <linux/printk.h> #include <linux/rcupdate.h>
+/* context number for fences without context, e.g: fence_collection */ +#define FENCE_NO_CONTEXT 0 + struct fence; struct fence_ops; struct fence_cb; @@ -292,6 +295,9 @@ static inline bool fence_is_later(struct fence *f1, struct fence *f2) if (WARN_ON(f1->context != f2->context)) return false;
+ if (WARN_ON(f1->context == FENCE_NO_CONTEXT)) + return false; + return (int)(f1->seqno - f2->seqno) > 0; }
@@ -309,6 +315,9 @@ static inline struct fence *fence_later(struct fence *f1, struct fence *f2) if (WARN_ON(f1->context != f2->context)) return NULL;
+ if (WARN_ON(f1->context == FENCE_NO_CONTEXT)) + return NULL; + /* * can't check just FENCE_FLAG_SIGNALED_BIT here, it may never have been * set if enable_signaling wasn't called, and enabling that here is