linux-kernel - [PATCH 2/7] dmaengine: sprd: Add validation of current descriptor in irq handler

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Date:   Mon, 15 Apr 2019 20:14:56 +0800
From:   Baolin Wang <baolin.wang@...aro.org>
To:     dan.j.williams@...el.com, vkoul@...nel.org
Cc:     eric.long@...soc.com, orsonzhai@...il.com, zhang.lyra@...il.com,
        broonie@...nel.org, baolin.wang@...aro.org,
        dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/7] dmaengine: sprd: Add validation of current descriptor in irq handler

When user terminates one DMA channel to free all its descriptors, but
at the same time one transaction interrupt was triggered possibly, now
we should not handle this interrupt by validating if the 'schan->cur_desc'
was set as NULL to avoid crashing the kernel.

Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
---
 drivers/dma/sprd-dma.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/sprd-dma.c b/drivers/dma/sprd-dma.c
index e29342a..431e289 100644
--- a/drivers/dma/sprd-dma.c
+++ b/drivers/dma/sprd-dma.c
@@ -552,12 +552,17 @@ static irqreturn_t dma_irq_handle(int irq, void *dev_id)
 		schan = &sdev->channels[i];
 
 		spin_lock(&schan->vc.lock);
+
+		sdesc = schan->cur_desc;
+		if (!sdesc) {
+			spin_unlock(&schan->vc.lock);
+			return IRQ_HANDLED;
+		}
+
 		int_type = sprd_dma_get_int_type(schan);
 		req_type = sprd_dma_get_req_type(schan);
 		sprd_dma_clear_int(schan);
 
-		sdesc = schan->cur_desc;
-
 		/* cyclic mode schedule callback */
 		cyclic = schan->linklist.phy_addr ? true : false;
 		if (cyclic == true) {
-- 
1.7.9.5