linux-kernel - [PATCH 08/10] dma: imx-sdma: abort updating channel when it has been terminated

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Date:	Tue, 17 May 2016 12:47:54 +0900
From:	Jiada Wang <jiada_wang@...tor.com>
To:	<vinod.koul@...el.com>, <dan.j.williams@...el.com>
CC:	<dmaengine@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<shawnguo@...nel.com>, <kernel@...gutronix.de>,
	<george_davis@...tor.com>, <jiada_wang@...tor.com>
Subject: [PATCH 08/10] dma: imx-sdma: abort updating channel when it has been terminated

In case the corresponding channel has already been terminated,
then instead of go on updating channel status, driver should abort from
sdma_handle_channel_loop(), otherwise channel status will be updated
incorrecly.

This patch also adds lock to avoid race between terminate of channel,
and updaing of channel status in sdma_handle_channel_loop().

Signed-off-by: Jiada Wang <jiada_wang@...tor.com>
---
 drivers/dma/imx-sdma.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index 0b23407..bc867e5 100644
--- a/drivers/dma/imx-sdma.c
+++ b/drivers/dma/imx-sdma.c
@@ -664,16 +664,25 @@ static void sdma_event_disable(struct sdma_channel *sdmac, unsigned int event)
 static void sdma_handle_channel_loop(struct sdma_channel *sdmac)
 {
 	struct sdma_buffer_descriptor *bd;
+	unsigned long flags;
 
 	/*
 	 * loop mode. Iterate over descriptors, re-setup them and
 	 * call callback function.
 	 */
 	while (1) {
+		spin_lock_irqsave(&sdmac->lock, flags);
+		if (!sdmac->enabled) {
+			spin_unlock_irqrestore(&sdmac->lock, flags);
+			break;
+		}
+
 		bd = &sdmac->bd[sdmac->buf_tail];
 
-		if (bd->mode.status & BD_DONE)
+		if (bd->mode.status & BD_DONE) {
+			spin_unlock_irqrestore(&sdmac->lock, flags);
 			break;
+		}
 
 		if (bd->mode.status & BD_RROR)
 			sdmac->status = DMA_ERROR;
@@ -690,6 +699,7 @@ static void sdma_handle_channel_loop(struct sdma_channel *sdmac)
 			bd->mode.count = sdmac->chn_count;
 		}
 
+		spin_unlock_irqrestore(&sdmac->lock, flags);
 		if (sdmac->desc.callback)
 			sdmac->desc.callback(sdmac->desc.callback_param);
 	}
-- 
2.4.5