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J . Mercier" , =?utf-8?q?Christian_K=C3=B6nig?= , Matthias Brugger , , , , , , , Subject: [PATCH v4,06/22] dma-heap: Add proper kref handling on dma-buf heaps Date: Mon, 29 Jan 2024 14:30:09 +0800 Message-ID: <20240129063025.29251-7-yunfei.dong@mediatek.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240129063025.29251-1-yunfei.dong@mediatek.com> References: <20240129063025.29251-1-yunfei.dong@mediatek.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MTK: N From: John Stultz Add proper refcounting 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 Signed-off-by: T.J. Mercier Signed-off-by: Yong Wu [Yong: Just add comment for "minor" and "refcount"] Signed-off-by: Yunfei Dong --- 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 22f6c193db0d..97025ee8500f 100644 --- a/drivers/dma-buf/dma-heap.c +++ b/drivers/dma-buf/dma-heap.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -30,6 +31,7 @@ * @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. */ @@ -40,6 +42,7 @@ struct dma_heap { dev_t heap_devt; struct list_head list; struct cdev heap_cdev; + struct kref refcount; }; static LIST_HEAD(heap_list); @@ -240,6 +243,7 @@ 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; @@ -304,6 +308,31 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) return err_ret; } +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 fbe86ec889a8..d57593f8a1bc 100644 --- a/include/linux/dma-heap.h +++ b/include/linux/dma-heap.h @@ -46,4 +46,6 @@ 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); + #endif /* _DMA_HEAPS_H */