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J . Mercier" , =?utf-8?q?Christian_K=C3=B6nig?= , Matthias Brugger , , , , , , Subject: [PATCH v7 05/28] dma-heap: Add proper kref handling on dma-buf heaps Date: Sat, 20 Jul 2024 15:15:43 +0800 Message-ID: <20240720071606.27930-6-yunfei.dong@mediatek.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240720071606.27930-1-yunfei.dong@mediatek.com> References: <20240720071606.27930-1-yunfei.dong@mediatek.com> MIME-Version: 1.0 X-TM-AS-Product-Ver: SMEX-14.0.0.3152-9.1.1006-23728.005 X-TM-AS-Result: No-10--5.707100-8.000000 X-TMASE-MatchedRID: uvmf2XsR/xmRKhTVQwgiGPOS+SRxjgFwIaLR+2xKRDJGL0g1nVmkYXB4 4IkzjfYyrUhQzMxACbqtTxRj9EhMYqh+3Rlbev+JEgwM8US/pTFYN1akkye0qOVyoVV0m7wN7fS O5z9h3Mjfbqj275Pjcy33B760297/lwV2iaAfSWcURSScn+QSXt0H8LFZNFG71sULACB0qRI987 fAqpfLD+SVyx8f84bFK4QcjwmrlwJjdxLGTzb+8v8Akuq1Mq2slExlQIQeRG0= X-TM-AS-User-Approved-Sender: No X-TM-AS-User-Blocked-Sender: No X-TMASE-Result: 10--5.707100-8.000000 X-TMASE-Version: SMEX-14.0.0.3152-9.1.1006-23728.005 X-TM-SNTS-SMTP: B5C727F956790980F61EEFCB8F9B46EAB3F94B842BBB02CD8E829204F26000262000:8 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240720_001622_404968_78A55784 X-CRM114-Status: GOOD ( 14.40 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: John Stultz 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 Signed-off-by: T.J. Mercier Signed-off-by: Yong Wu [Yong: Just add comment for "minor" and "refcount"] Signed-off-by: Yunfei Dong [Yunfei: Change reviewer's comments] --- 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 */