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authorJohn Stultz <john.stultz@linaro.org>2013-12-17 17:04:29 -0800
committerColin Cross <ccross@android.com>2013-12-19 19:25:39 -0800
commitc6448537fe9e8b684b214e89c6c68c3b209f549e (patch)
treec1703427892a1871b9184470dfcc98f262790277 /drivers/staging
parent60e11dfc002962181fe4f0db54b33c65fee02c52 (diff)
downloadlinaro-lsk-c6448537fe9e8b684b214e89c6c68c3b209f549e.tar.gz
staging: ion: Avoid using rt_mutexes directly
RT_MUTEXES can be configured out of the kernel, causing compile problems with ION. To quote Colin: "rt_mutexes were added with the deferred freeing feature. Heaps need to return zeroed memory to userspace, but zeroing the memory on every allocation was causing performance issues. We added a SCHED_IDLE thread to zero memory in the background after freeing, but locking the heap from the SCHED_IDLE thread might block a high priority allocation thread for a long time. The lock is only used to protect the heap's free_list and free_list_size members, and is not held for any long or sleeping operations. Converting to a spinlock should prevent priority inversion without using the rt_mutex. I'd also rename it to free_lock to so it doesn't get used as a general heap lock." Thus this patch converts the rt_mutex usage to a spinlock and renames the lock free_lock to be more clear as to its use. I also had to change a bit of logic in ion_heap_freelist_drain() to safely avoid list corruption. Acked-by: Colin Cross <ccross@android.com> Cc: Android Kernel Team <kernel-team@android.com> Reported-by: Jim Davis <jim.epost@gmail.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging')
-rw-r--r--drivers/staging/android/ion/ion_heap.c28
-rw-r--r--drivers/staging/android/ion/ion_priv.h2
2 files changed, 17 insertions, 13 deletions
diff --git a/drivers/staging/android/ion/ion_heap.c b/drivers/staging/android/ion/ion_heap.c
index 5b01e9e30a4..96feebb6ad7 100644
--- a/drivers/staging/android/ion/ion_heap.c
+++ b/drivers/staging/android/ion/ion_heap.c
@@ -160,10 +160,10 @@ int ion_heap_pages_zero(struct page *page, size_t size, pgprot_t pgprot)
void ion_heap_freelist_add(struct ion_heap *heap, struct ion_buffer *buffer)
{
- rt_mutex_lock(&heap->lock);
+ spin_lock(&heap->free_lock);
list_add(&buffer->list, &heap->free_list);
heap->free_list_size += buffer->size;
- rt_mutex_unlock(&heap->lock);
+ spin_unlock(&heap->free_lock);
wake_up(&heap->waitqueue);
}
@@ -171,34 +171,38 @@ size_t ion_heap_freelist_size(struct ion_heap *heap)
{
size_t size;
- rt_mutex_lock(&heap->lock);
+ spin_lock(&heap->free_lock);
size = heap->free_list_size;
- rt_mutex_unlock(&heap->lock);
+ spin_unlock(&heap->free_lock);
return size;
}
size_t ion_heap_freelist_drain(struct ion_heap *heap, size_t size)
{
- struct ion_buffer *buffer, *tmp;
+ struct ion_buffer *buffer;
size_t total_drained = 0;
if (ion_heap_freelist_size(heap) == 0)
return 0;
- rt_mutex_lock(&heap->lock);
+ spin_lock(&heap->free_lock);
if (size == 0)
size = heap->free_list_size;
- list_for_each_entry_safe(buffer, tmp, &heap->free_list, list) {
+ while (!list_empty(&heap->free_list)) {
if (total_drained >= size)
break;
+ buffer = list_first_entry(&heap->free_list, struct ion_buffer,
+ list);
list_del(&buffer->list);
heap->free_list_size -= buffer->size;
total_drained += buffer->size;
+ spin_unlock(&heap->free_lock);
ion_buffer_destroy(buffer);
+ spin_lock(&heap->free_lock);
}
- rt_mutex_unlock(&heap->lock);
+ spin_unlock(&heap->free_lock);
return total_drained;
}
@@ -213,16 +217,16 @@ static int ion_heap_deferred_free(void *data)
wait_event_freezable(heap->waitqueue,
ion_heap_freelist_size(heap) > 0);
- rt_mutex_lock(&heap->lock);
+ spin_lock(&heap->free_lock);
if (list_empty(&heap->free_list)) {
- rt_mutex_unlock(&heap->lock);
+ spin_unlock(&heap->free_lock);
continue;
}
buffer = list_first_entry(&heap->free_list, struct ion_buffer,
list);
list_del(&buffer->list);
heap->free_list_size -= buffer->size;
- rt_mutex_unlock(&heap->lock);
+ spin_unlock(&heap->free_lock);
ion_buffer_destroy(buffer);
}
@@ -235,7 +239,7 @@ int ion_heap_init_deferred_free(struct ion_heap *heap)
INIT_LIST_HEAD(&heap->free_list);
heap->free_list_size = 0;
- rt_mutex_init(&heap->lock);
+ spin_lock_init(&heap->free_lock);
init_waitqueue_head(&heap->waitqueue);
heap->task = kthread_run(ion_heap_deferred_free, heap,
"%s", heap->name);
diff --git a/drivers/staging/android/ion/ion_priv.h b/drivers/staging/android/ion/ion_priv.h
index ac625b11505..58e84cc8148 100644
--- a/drivers/staging/android/ion/ion_priv.h
+++ b/drivers/staging/android/ion/ion_priv.h
@@ -160,7 +160,7 @@ struct ion_heap {
struct shrinker shrinker;
struct list_head free_list;
size_t free_list_size;
- struct rt_mutex lock;
+ spinlock_t free_lock;
wait_queue_head_t waitqueue;
struct task_struct *task;
int (*debug_show)(struct ion_heap *heap, struct seq_file *, void *);