serial: sirf: fix endless loop bug in uart receive tasklet

In special condition, when cpu schedule into rx_tmo_process_tl or
rx_dma_complete_tl and all the receive dma tasks have done, it will
go into endless loop because no dma task cookie status be changed.

Signed-off-by: Qipan Li <Qipan.Li@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/sirfsoc_uart.c b/drivers/tty/serial/sirfsoc_uart.c
index 48cceaf..ffeb766 100644 (file)
--- a/drivers/tty/serial/sirfsoc_uart.c
+++ b/drivers/tty/serial/sirfsoc_uart.c
@@ -488,6 +488,7 @@ static void sirfsoc_rx_tmo_process_tl(unsigned long param)
        unsigned int count;
        struct dma_tx_state tx_state;
        unsigned long flags;
+       int i = 0;
 
        spin_lock_irqsave(&port->lock, flags);
        while (DMA_COMPLETE == dmaengine_tx_status(sirfport->rx_dma_chan,
@@ -497,6 +498,9 @@ static void sirfsoc_rx_tmo_process_tl(unsigned long param)
                                        SIRFSOC_RX_DMA_BUF_SIZE);
                sirfport->rx_completed++;
                sirfport->rx_completed %= SIRFSOC_RX_LOOP_BUF_CNT;
+               i++;
+               if (i > SIRFSOC_RX_LOOP_BUF_CNT)
+                       break;
        }
        count = CIRC_CNT(sirfport->rx_dma_items[sirfport->rx_issued].xmit.head,
                sirfport->rx_dma_items[sirfport->rx_issued].xmit.tail,
@@ -713,6 +717,8 @@ static void sirfsoc_uart_rx_dma_complete_tl(unsigned long param)
        struct sirfsoc_int_en *uint_en = &sirfport->uart_reg->uart_int_en;
        struct dma_tx_state tx_state;
        unsigned long flags;
+       int i = 0;
+
        spin_lock_irqsave(&port->lock, flags);
        while (DMA_COMPLETE == dmaengine_tx_status(sirfport->rx_dma_chan,
                sirfport->rx_dma_items[sirfport->rx_completed].cookie,
@@ -726,6 +732,9 @@ static void sirfsoc_uart_rx_dma_complete_tl(unsigned long param)
                else
                        sirfport->rx_completed++;
                sirfport->rx_completed %= SIRFSOC_RX_LOOP_BUF_CNT;
+               i++;
+               if (i > SIRFSOC_RX_LOOP_BUF_CNT)
+                       break;
        }
        spin_unlock_irqrestore(&port->lock, flags);
        tty_flip_buffer_push(&port->state->port);