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Subject[PATCH 061/115] gpu: ion: Make ion_free asynchronous
Date
From: Rebecca Schultz Zavin <rebecca@android.com>

Add the ability for a heap to free buffers asynchrounously. Freed buffers
are placed on a free list and freed from a low priority background thread.
If allocations from a particular heap fail, the free list is drained. This
patch also enable asynchronous frees from the chunk heap.

Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
[jstultz: modified patch to apply to staging directory]
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
drivers/staging/android/ion/ion.c | 112 +++++++++++++++++++++++---
drivers/staging/android/ion/ion.h | 2 +-
drivers/staging/android/ion/ion_chunk_heap.c | 3 +-
drivers/staging/android/ion/ion_priv.h | 20 ++++-
drivers/staging/android/ion/ion_system_heap.c | 1 +
5 files changed, 126 insertions(+), 12 deletions(-)

diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index ba65bef..b965f15 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -17,8 +17,10 @@

#include <linux/device.h>
#include <linux/file.h>
+#include <linux/freezer.h>
#include <linux/fs.h>
#include <linux/anon_inodes.h>
+#include <linux/kthread.h>
#include <linux/list.h>
#include <linux/memblock.h>
#include <linux/miscdevice.h>
@@ -26,6 +28,7 @@
#include <linux/mm.h>
#include <linux/mm_types.h>
#include <linux/rbtree.h>
+#include <linux/rtmutex.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
@@ -140,6 +143,7 @@ static void ion_buffer_add(struct ion_device *dev,

static int ion_buffer_alloc_dirty(struct ion_buffer *buffer);

+static bool ion_heap_drain_freelist(struct ion_heap *heap);
/* this function should only be called while dev->lock is held */
static struct ion_buffer *ion_buffer_create(struct ion_heap *heap,
struct ion_device *dev,
@@ -161,9 +165,16 @@ static struct ion_buffer *ion_buffer_create(struct ion_heap *heap,
kref_init(&buffer->ref);

ret = heap->ops->allocate(heap, buffer, len, align, flags);
+
if (ret) {
- kfree(buffer);
- return ERR_PTR(ret);
+ if (!(heap->flags & ION_HEAP_FLAG_DEFER_FREE))
+ goto err2;
+
+ ion_heap_drain_freelist(heap);
+ ret = heap->ops->allocate(heap, buffer, len, align,
+ flags);
+ if (ret)
+ goto err2;
}

buffer->dev = dev;
@@ -214,27 +225,42 @@ static struct ion_buffer *ion_buffer_create(struct ion_heap *heap,
err:
heap->ops->unmap_dma(heap, buffer);
heap->ops->free(buffer);
+err2:
kfree(buffer);
return ERR_PTR(ret);
}

-static void ion_buffer_destroy(struct kref *kref)
+static void _ion_buffer_destroy(struct ion_buffer *buffer)
{
- struct ion_buffer *buffer = container_of(kref, struct ion_buffer, ref);
- struct ion_device *dev = buffer->dev;
-
if (WARN_ON(buffer->kmap_cnt > 0))
buffer->heap->ops->unmap_kernel(buffer->heap, buffer);
buffer->heap->ops->unmap_dma(buffer->heap, buffer);
buffer->heap->ops->free(buffer);
- mutex_lock(&dev->buffer_lock);
- rb_erase(&buffer->node, &dev->buffers);
- mutex_unlock(&dev->buffer_lock);
if (buffer->flags & ION_FLAG_CACHED)
kfree(buffer->dirty);
kfree(buffer);
}

+static void ion_buffer_destroy(struct kref *kref)
+{
+ struct ion_buffer *buffer = container_of(kref, struct ion_buffer, ref);
+ struct ion_heap *heap = buffer->heap;
+ struct ion_device *dev = buffer->dev;
+
+ mutex_lock(&dev->buffer_lock);
+ rb_erase(&buffer->node, &dev->buffers);
+ mutex_unlock(&dev->buffer_lock);
+
+ if (heap->flags & ION_HEAP_FLAG_DEFER_FREE) {
+ rt_mutex_lock(&heap->lock);
+ list_add(&buffer->list, &heap->free_list);
+ rt_mutex_unlock(&heap->lock);
+ wake_up(&heap->waitqueue);
+ return;
+ }
+ _ion_buffer_destroy(buffer);
+}
+
static void ion_buffer_get(struct ion_buffer *buffer)
{
kref_get(&buffer->ref);
@@ -1272,13 +1298,81 @@ static const struct file_operations debug_heap_fops = {
.release = single_release,
};

+static size_t ion_heap_free_list_is_empty(struct ion_heap *heap)
+{
+ bool is_empty;
+
+ rt_mutex_lock(&heap->lock);
+ is_empty = list_empty(&heap->free_list);
+ rt_mutex_unlock(&heap->lock);
+
+ return is_empty;
+}
+
+static int ion_heap_deferred_free(void *data)
+{
+ struct ion_heap *heap = data;
+
+ while (true) {
+ struct ion_buffer *buffer;
+
+ wait_event_freezable(heap->waitqueue,
+ !ion_heap_free_list_is_empty(heap));
+
+ rt_mutex_lock(&heap->lock);
+ if (list_empty(&heap->free_list)) {
+ rt_mutex_unlock(&heap->lock);
+ continue;
+ }
+ buffer = list_first_entry(&heap->free_list, struct ion_buffer,
+ list);
+ list_del(&buffer->list);
+ rt_mutex_unlock(&heap->lock);
+ _ion_buffer_destroy(buffer);
+ }
+
+ return 0;
+}
+
+static bool ion_heap_drain_freelist(struct ion_heap *heap)
+{
+ struct ion_buffer *buffer, *tmp;
+
+ if (ion_heap_free_list_is_empty(heap))
+ return false;
+ rt_mutex_lock(&heap->lock);
+ list_for_each_entry_safe(buffer, tmp, &heap->free_list, list) {
+ _ion_buffer_destroy(buffer);
+ list_del(&buffer->list);
+ }
+ BUG_ON(!list_empty(&heap->free_list));
+ rt_mutex_unlock(&heap->lock);
+
+
+ return true;
+}
+
void ion_device_add_heap(struct ion_device *dev, struct ion_heap *heap)
{
+ struct sched_param param = { .sched_priority = 0 };
+
if (!heap->ops->allocate || !heap->ops->free || !heap->ops->map_dma ||
!heap->ops->unmap_dma)
pr_err("%s: can not add heap with invalid ops struct.\n",
__func__);

+ if (heap->flags & ION_HEAP_FLAG_DEFER_FREE) {
+ INIT_LIST_HEAD(&heap->free_list);
+ rt_mutex_init(&heap->lock);
+ init_waitqueue_head(&heap->waitqueue);
+ heap->task = kthread_run(ion_heap_deferred_free, heap,
+ "%s", heap->name);
+ sched_setscheduler(heap->task, SCHED_IDLE, &param);
+ if (IS_ERR(heap->task))
+ pr_err("%s: creating thread for deferred free failed\n",
+ __func__);
+ }
+
heap->dev = dev;
down_write(&dev->lock);
/* use negative heap->id to reverse the priority -- when traversing
diff --git a/drivers/staging/android/ion/ion.h b/drivers/staging/android/ion/ion.h
index 976123b..679031c 100644
--- a/drivers/staging/android/ion/ion.h
+++ b/drivers/staging/android/ion/ion.h
@@ -46,7 +46,7 @@ enum ion_heap_type {
#define ION_NUM_HEAP_IDS sizeof(unsigned int) * 8

/**
- * heap flags - the lower 16 bits are used by core ion, the upper 16
+ * allocation flags - the lower 16 bits are used by core ion, the upper 16
* bits are reserved for use by the heaps themselves.
*/
#define ION_FLAG_CACHED 1 /* mappings of this buffer should be
diff --git a/drivers/staging/android/ion/ion_chunk_heap.c b/drivers/staging/android/ion/ion_chunk_heap.c
index 60cd91c..ac7cf13 100644
--- a/drivers/staging/android/ion/ion_chunk_heap.c
+++ b/drivers/staging/android/ion/ion_chunk_heap.c
@@ -160,7 +160,8 @@ struct ion_heap *ion_chunk_heap_create(struct ion_platform_heap *heap_data)
gen_pool_add(chunk_heap->pool, chunk_heap->base, heap_data->size, -1);
chunk_heap->heap.ops = &chunk_heap_ops;
chunk_heap->heap.type = ION_HEAP_TYPE_CHUNK;
- pr_info("%s: base %lu size %ld align %ld\n", __func__, chunk_heap->base,
+ chunk_heap->heap.flags = ION_HEAP_FLAG_DEFER_FREE;
+ pr_info("%s: base %lu size %u align %ld\n", __func__, chunk_heap->base,
heap_data->size, heap_data->align);

return &chunk_heap->heap;
diff --git a/drivers/staging/android/ion/ion_priv.h b/drivers/staging/android/ion/ion_priv.h
index cfb4264..ab1a8d9 100644
--- a/drivers/staging/android/ion/ion_priv.h
+++ b/drivers/staging/android/ion/ion_priv.h
@@ -58,7 +58,10 @@ struct ion_buffer *ion_handle_buffer(struct ion_handle *handle);
*/
struct ion_buffer {
struct kref ref;
- struct rb_node node;
+ union {
+ struct rb_node node;
+ struct list_head list;
+ };
struct ion_device *dev;
struct ion_heap *heap;
unsigned long flags;
@@ -109,15 +112,25 @@ struct ion_heap_ops {
};

/**
+ * heap flags - flags between the heaps and core ion code
+ */
+#define ION_HEAP_FLAG_DEFER_FREE (1 << 0)
+
+/**
* struct ion_heap - represents a heap in the system
* @node: rb node to put the heap on the device's tree of heaps
* @dev: back pointer to the ion_device
* @type: type of heap
* @ops: ops struct as above
+ * @flags: flags
* @id: id of heap, also indicates priority of this heap when
* allocating. These are specified by platform data and
* MUST be unique
* @name: used for debugging
+ * @free_list: free list head if deferred free is used
+ * @lock: protects the free list
+ * @waitqueue: queue to wait on from deferred free thread
+ * @task: task struct of deferred free thread
* @debug_show: called when heap debug file is read to add any
* heap specific debug info to output
*
@@ -131,8 +144,13 @@ struct ion_heap {
struct ion_device *dev;
enum ion_heap_type type;
struct ion_heap_ops *ops;
+ unsigned long flags;
unsigned int id;
const char *name;
+ struct list_head free_list;
+ struct rt_mutex lock;
+ wait_queue_head_t waitqueue;
+ struct task_struct *task;
int (*debug_show)(struct ion_heap *heap, struct seq_file *, void *);
};

diff --git a/drivers/staging/android/ion/ion_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c
index 3ca704e..6665797 100644
--- a/drivers/staging/android/ion/ion_system_heap.c
+++ b/drivers/staging/android/ion/ion_system_heap.c
@@ -283,6 +283,7 @@ struct ion_heap *ion_system_heap_create(struct ion_platform_heap *unused)
return ERR_PTR(-ENOMEM);
heap->heap.ops = &system_heap_ops;
heap->heap.type = ION_HEAP_TYPE_SYSTEM;
+ heap->heap.flags = ION_HEAP_FLAG_DEFER_FREE;
heap->pools = kzalloc(sizeof(struct ion_page_pool *) * num_orders,
GFP_KERNEL);
if (!heap->pools)
--
1.8.3.2


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