serial: bfin-uart: avoid dead lock in rx irq handler in smp kernel
Disabing dma irq and lock bottom half in smp kernel doesn't ensure exclusive
uart access. Call spin_lock_irqsave() instead.
Signed-off-by: Steven Miao <realmz6@gmail.com>
Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/serial/bfin_uart.c b/drivers/tty/serial/bfin_uart.c
index 9242d56..ca64c4a 100644
--- a/drivers/tty/serial/bfin_uart.c
+++ b/drivers/tty/serial/bfin_uart.c
@@ -477,9 +477,9 @@
void bfin_serial_rx_dma_timeout(struct bfin_serial_port *uart)
{
int x_pos, pos;
+ unsigned long flags;
- dma_disable_irq_nosync(uart->rx_dma_channel);
- spin_lock_bh(&uart->rx_lock);
+ spin_lock_irqsave(&uart->rx_lock, flags);
/* 2D DMA RX buffer ring is used. Because curr_y_count and
* curr_x_count can't be read as an atomic operation,
@@ -510,8 +510,7 @@
uart->rx_dma_buf.tail = uart->rx_dma_buf.head;
}
- spin_unlock_bh(&uart->rx_lock);
- dma_enable_irq(uart->rx_dma_channel);
+ spin_unlock_irqrestore(&uart->rx_lock, flags);
mod_timer(&(uart->rx_dma_timer), jiffies + DMA_RX_FLUSH_JIFFIES);
}