dmaengine: imx-dma: fix missing irq disable in tasklet

Commit Message

Dirk Behme Nov. 9, 2012, 7 a.m. UTC

From: Andreas Pape <[e-mail]>

Interrupt handler uses spinlock, too.
To avoid deadlock tasklet must disable IRQ.

Signed-off-by: Andreas Pape <[e-mail]>
CC: Vinod Koul <[e-mail]>
CC: Javier Martin <[e-mail]>
CC: Sascha Hauer <[e-mail]>
---

I'm no DMA expert, so sorry if it's wrong ;)

And btw.: While looking at this code, we wonder if imxdma_xfer_desc() can
get the spin lock recursively, e.g. from imxdma_tasklet()? Or what ensures
that the lock is always taken from an other DMA engine than the one already
holding the lock? 

 drivers/dma/imx-dma.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

Patch

diff --git a/drivers/dma/imx-dma.c b/drivers/dma/imx-dma.c
index 7d9554c..bce30e8 100644
--- a/drivers/dma/imx-dma.c
+++ b/drivers/dma/imx-dma.c
@@ -562,8 +562,9 @@  static void imxdma_tasklet(unsigned long data)
 	struct imxdma_channel *imxdmac = (void *)data;
 	struct imxdma_engine *imxdma = imxdmac->imxdma;
 	struct imxdma_desc *desc;
+	unsigned long flags;
 
-	spin_lock(&imxdma->lock);
+	spin_lock_irqsave(&imxdma->lock, flags);
 
 	if (list_empty(&imxdmac->ld_active)) {
 		/* Someone might have called terminate all */
@@ -600,7 +601,7 @@  static void imxdma_tasklet(unsigned long data)
 				 __func__, imxdmac->channel);
 	}
 out:
-	spin_unlock(&imxdma->lock);
+	spin_unlock_irqrestore(&imxdma->lock, flags);
 }
 
 static int imxdma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,