From 8a31f8b5db65b860fd0d358dc27f6daf26074406 Mon Sep 17 00:00:00 2001 From: Sinan Kaya Date: Wed, 31 Aug 2016 11:10:27 -0400 Subject: [PATCH] dmaengine: qcom_hidma: release the descriptor before the callback There is a race condition between data transfer callback and descriptor free code. The callback routine may decide to clear the resources even though the descriptor has not yet been freed. Instead of calling the callback first and then releasing the memory, this code is changing the order to return the descriptor back to the free pool and then call the user provided callback. Signed-off-by: Sinan Kaya Signed-off-by: Vinod Koul --- drivers/dma/qcom/hidma.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/drivers/dma/qcom/hidma.c b/drivers/dma/qcom/hidma.c index 1197fbf..b8493ba 100644 --- a/drivers/dma/qcom/hidma.c +++ b/drivers/dma/qcom/hidma.c @@ -111,6 +111,7 @@ static void hidma_process_completed(struct hidma_chan *mchan) struct dma_async_tx_descriptor *desc; dma_cookie_t last_cookie; struct hidma_desc *mdesc; + struct hidma_desc *next; unsigned long irqflags; struct list_head list; @@ -122,8 +123,9 @@ static void hidma_process_completed(struct hidma_chan *mchan) spin_unlock_irqrestore(&mchan->lock, irqflags); /* Execute callbacks and run dependencies */ - list_for_each_entry(mdesc, &list, node) { + list_for_each_entry_safe(mdesc, next, &list, node) { enum dma_status llstat; + struct dmaengine_desc_callback cb; desc = &mdesc->desc; @@ -132,18 +134,18 @@ static void hidma_process_completed(struct hidma_chan *mchan) spin_unlock_irqrestore(&mchan->lock, irqflags); llstat = hidma_ll_status(mdma->lldev, mdesc->tre_ch); - if (llstat == DMA_COMPLETE) - dmaengine_desc_get_callback_invoke(desc, NULL); + dmaengine_desc_get_callback(desc, &cb); last_cookie = desc->cookie; dma_run_dependencies(desc); - } - /* Free descriptors */ - spin_lock_irqsave(&mchan->lock, irqflags); - list_splice_tail_init(&list, &mchan->free); - spin_unlock_irqrestore(&mchan->lock, irqflags); + spin_lock_irqsave(&mchan->lock, irqflags); + list_move(&mdesc->node, &mchan->free); + spin_unlock_irqrestore(&mchan->lock, irqflags); + if (llstat == DMA_COMPLETE) + dmaengine_desc_callback_invoke(&cb, NULL); + } } /* -- 2.7.4