tty: serial: fsl_lpuart: check dma_tx_in_progress in tx dma callback

There have a corner case that tx DMA .callback() is coming after
.flush_buffer(), then .callback() should check dma_tx_in_progress
flag and return in directly.

Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: Vipul Kumar <vipul_kumar@mentor.com>
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20210817100203.21300-1-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index f0e5da7..31d715c 100644 (file)
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -479,6 +479,10 @@ static void lpuart_dma_tx_complete(void *arg)
        unsigned long flags;
 
        spin_lock_irqsave(&sport->port.lock, flags);
+       if (!sport->dma_tx_in_progress) {
+               spin_unlock_irqrestore(&sport->port.lock, flags);
+               return;
+       }
 
        dma_unmap_sg(chan->device->dev, sgl, sport->dma_tx_nents,
                     DMA_TO_DEVICE);