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Davis" , Benjamin Gaignard , Liam Mark , Laura Abbott , Brian Starkey , linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: [RFC][PATCH] dma-heap: Add proper kref handling on dma-buf heaps Date: Sat, 25 Jul 2020 03:26:33 +0000 Message-Id: <20200725032633.125006-1-john.stultz@linaro.org> X-Mailer: git-send-email 2.17.1 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 Cc: Sumit Semwal Cc: Andrew F. Davis Cc: Benjamin Gaignard Cc: Liam Mark Cc: Laura Abbott Cc: Brian Starkey Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Signed-off-by: John Stultz --- drivers/dma-buf/dma-heap.c | 31 +++++++++++++++++++++++++++---- include/linux/dma-heap.h | 6 ++++++ 2 files changed, 33 insertions(+), 4 deletions(-) -- 2.17.1 diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c index afd22c9dbdcf..90c3720acc1c 100644 --- a/drivers/dma-buf/dma-heap.c +++ b/drivers/dma-buf/dma-heap.c @@ -40,6 +40,8 @@ struct dma_heap { dev_t heap_devt; struct list_head list; struct cdev heap_cdev; + int minor; + struct kref refcount; }; static LIST_HEAD(heap_list); @@ -190,11 +192,31 @@ void *dma_heap_get_drvdata(struct dma_heap *heap) return heap->priv; } +static void dma_heap_release(struct kref *ref) +{ + struct dma_heap *heap = container_of(ref, struct dma_heap, refcount); + + /* Remove heap from the list */ + 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, heap->minor); + + kfree(heap); +} + +void dma_heap_put(struct dma_heap *h) +{ + kref_put(&h->refcount, dma_heap_release); +} + struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) { struct dma_heap *heap, *h, *err_ret; struct device *dev_ret; - unsigned int minor; int ret; if (!exp_info->name || !strcmp(exp_info->name, "")) { @@ -223,12 +245,13 @@ 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; /* Find unused minor number */ - ret = xa_alloc(&dma_heap_minors, &minor, heap, + ret = xa_alloc(&dma_heap_minors, &heap->minor, heap, XA_LIMIT(0, NUM_HEAP_MINORS - 1), GFP_KERNEL); if (ret < 0) { pr_err("dma_heap: Unable to get minor number for heap\n"); @@ -237,7 +260,7 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) } /* Create device */ - heap->heap_devt = MKDEV(MAJOR(dma_heap_devt), minor); + heap->heap_devt = MKDEV(MAJOR(dma_heap_devt), heap->minor); cdev_init(&heap->heap_cdev, &dma_heap_fops); ret = cdev_add(&heap->heap_cdev, heap->heap_devt, 1); @@ -267,7 +290,7 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) err2: cdev_del(&heap->heap_cdev); err1: - xa_erase(&dma_heap_minors, minor); + xa_erase(&dma_heap_minors, heap->minor); err0: kfree(heap); return err_ret; diff --git a/include/linux/dma-heap.h b/include/linux/dma-heap.h index 454e354d1ffb..c1572f29cfac 100644 --- a/include/linux/dma-heap.h +++ b/include/linux/dma-heap.h @@ -56,4 +56,10 @@ void *dma_heap_get_drvdata(struct dma_heap *heap); */ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info); +/** + * dma_heap_put - drops a reference to a dmabuf heaps, potentially freeing it + * @heap: heap pointer + */ +void dma_heap_put(struct dma_heap *heap); + #endif /* _DMA_HEAPS_H */