From: John Stultz jstultz@google.com
Add proper reference counting on the dma_heap structure. While existing heaps are built-in, we may eventually have heaps loaded from modules, and we'll need to be able to properly handle the references to the heaps
Signed-off-by: John Stultz jstultz@google.com Signed-off-by: T.J. Mercier tjmercier@google.com Signed-off-by: Yong Wu yong.wu@mediatek.com [Yong: Just add comment for "minor" and "refcount"] Signed-off-by: Yunfei Dong yunfei.dong@mediatek.com [Yunfei: Change reviewer's comments] Signed-off-by: Florent Tomasin florent.tomasin@arm.com [Florent: Rebase] Signed-off-by: Ketil Johnsen ketil.johnsen@arm.com [Ketil: Rebase] --- drivers/dma-buf/dma-heap.c | 29 +++++++++++++++++++++++++++++ include/linux/dma-heap.h | 2 ++ 2 files changed, 31 insertions(+)
diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c index ac5f8685a6494..9fd365ddbd517 100644 --- a/drivers/dma-buf/dma-heap.c +++ b/drivers/dma-buf/dma-heap.c @@ -12,6 +12,7 @@ #include <linux/dma-heap.h> #include <linux/err.h> #include <linux/export.h> +#include <linux/kref.h> #include <linux/list.h> #include <linux/nospec.h> #include <linux/syscalls.h> @@ -31,6 +32,7 @@ * @heap_devt: heap device node * @list: list head connecting to list of heaps * @heap_cdev: heap char device + * @refcount: reference counter for this heap device * * Represents a heap of memory from which buffers can be made. */ @@ -41,6 +43,7 @@ struct dma_heap { dev_t heap_devt; struct list_head list; struct cdev heap_cdev; + struct kref refcount; };
static LIST_HEAD(heap_list); @@ -248,6 +251,7 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) if (!heap) return ERR_PTR(-ENOMEM);
+ kref_init(&heap->refcount); heap->name = exp_info->name; heap->ops = exp_info->ops; heap->priv = exp_info->priv; @@ -313,6 +317,31 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) } EXPORT_SYMBOL_NS_GPL(dma_heap_add, "DMA_BUF_HEAP");
+static void dma_heap_release(struct kref *ref) +{ + struct dma_heap *heap = container_of(ref, struct dma_heap, refcount); + unsigned int minor = MINOR(heap->heap_devt); + + mutex_lock(&heap_list_lock); + list_del(&heap->list); + mutex_unlock(&heap_list_lock); + + device_destroy(dma_heap_class, heap->heap_devt); + cdev_del(&heap->heap_cdev); + xa_erase(&dma_heap_minors, minor); + + kfree(heap); +} + +/** + * dma_heap_put - drops a reference to a dmabuf heap, potentially freeing it + * @heap: DMA-Heap whose reference count to decrement + */ +void dma_heap_put(struct dma_heap *heap) +{ + kref_put(&heap->refcount, dma_heap_release); +} + static char *dma_heap_devnode(const struct device *dev, umode_t *mode) { return kasprintf(GFP_KERNEL, "dma_heap/%s", dev_name(dev)); diff --git a/include/linux/dma-heap.h b/include/linux/dma-heap.h index 648328a64b27e..ff57741700f5f 100644 --- a/include/linux/dma-heap.h +++ b/include/linux/dma-heap.h @@ -46,6 +46,8 @@ const char *dma_heap_get_name(struct dma_heap *heap);
struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info);
+void dma_heap_put(struct dma_heap *heap); + extern bool mem_accounting;
#endif /* _DMA_HEAPS_H */