dmaengine: imx-sdma: fix pagefault when channel is disabled during interrupt

Add a spinlock and a 'enabled' boolean on channel descriptor, to avoid
using buffer descriptors in the interrupt context,
when sdma_disable_channel is called meanwhile.

Signed-off-by: Thierry Bultel <tbultel@pixelsurmer.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index e7db24c..ccd03c3 100644 (file)
--- a/drivers/dma/imx-sdma.c
+++ b/drivers/dma/imx-sdma.c
@@ -338,6 +338,7 @@ struct sdma_channel {
        unsigned int                    chn_real_count;
        struct tasklet_struct           tasklet;
        struct imx_dma_data             data;
+       bool                            enabled;
 };
 
 #define IMX_DMA_SG_LOOP                BIT(0)
@@ -596,7 +597,14 @@ static int sdma_config_ownership(struct sdma_channel *sdmac,
 
 static void sdma_enable_channel(struct sdma_engine *sdma, int channel)
 {
+       unsigned long flags;
+       struct sdma_channel *sdmac = &sdma->channel[channel];
+
        writel(BIT(channel), sdma->regs + SDMA_H_START);
+
+       spin_lock_irqsave(&sdmac->lock, flags);
+       sdmac->enabled = true;
+       spin_unlock_irqrestore(&sdmac->lock, flags);
 }
 
 /*
@@ -685,6 +693,14 @@ static void sdma_update_channel_loop(struct sdma_channel *sdmac)
        struct sdma_buffer_descriptor *bd;
        int error = 0;
        enum dma_status old_status = sdmac->status;
+       unsigned long flags;
+
+       spin_lock_irqsave(&sdmac->lock, flags);
+       if (!sdmac->enabled) {
+               spin_unlock_irqrestore(&sdmac->lock, flags);
+               return;
+       }
+       spin_unlock_irqrestore(&sdmac->lock, flags);
 
        /*
         * loop mode. Iterate over descriptors, re-setup them and
@@ -938,10 +954,15 @@ static int sdma_disable_channel(struct dma_chan *chan)
        struct sdma_channel *sdmac = to_sdma_chan(chan);
        struct sdma_engine *sdma = sdmac->sdma;
        int channel = sdmac->channel;
+       unsigned long flags;
 
        writel_relaxed(BIT(channel), sdma->regs + SDMA_H_STATSTOP);
        sdmac->status = DMA_ERROR;
 
+       spin_lock_irqsave(&sdmac->lock, flags);
+       sdmac->enabled = false;
+       spin_unlock_irqrestore(&sdmac->lock, flags);
+
        return 0;
 }