spi: bcm2835: Fix race on DMA termination

[sfrench/cifs-2.6.git] / drivers / spi / spi-bcm2835.c

diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index 594e9712ecbcbf22b13d4f4bcaf18297c5c23865..774161bbcb2e90b803d9ccf2c55559b79536de55 100644 (file)
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -232,10 +232,9 @@ static void bcm2835_spi_dma_done(void *data)
         * is called the tx-dma must have finished - can't get to this
         * situation otherwise...
         */
-       dmaengine_terminate_all(master->dma_tx);
-
-       /* mark as no longer pending */
-       bs->dma_pending = 0;
+       if (cmpxchg(&bs->dma_pending, true, false)) {
+               dmaengine_terminate_all(master->dma_tx);
+       }
 
        /* and mark as completed */;
        complete(&master->xfer_completion);
@@ -617,10 +616,9 @@ static void bcm2835_spi_handle_err(struct spi_master *master,
        struct bcm2835_spi *bs = spi_master_get_devdata(master);
 
        /* if an error occurred and we have an active dma, then terminate */
-       if (bs->dma_pending) {
+       if (cmpxchg(&bs->dma_pending, true, false)) {
                dmaengine_terminate_all(master->dma_tx);
                dmaengine_terminate_all(master->dma_rx);
-               bs->dma_pending = 0;
        }
        /* and reset */
        bcm2835_spi_reset_hw(master);