From 9642dbe73c8a3b55a812253fcb9add9eeed4ca81 Mon Sep 17 00:00:00 2001
From: Steven Miao <realmz6@gmail.com>
Date: Wed, 7 Nov 2012 13:27:56 +0800
Subject: [PATCH] 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>
---
drivers/tty/serial/bfin_uart.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/tty/serial/bfin_uart.c b/drivers/tty/serial/bfin_uart.c
index 9242d56ba2670..ca64c4a83ce05 100644
--- a/drivers/tty/serial/bfin_uart.c
+++ b/drivers/tty/serial/bfin_uart.c
@@ -477,9 +477,9 @@ static void bfin_serial_dma_rx_chars(struct bfin_serial_port *uart)
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 @@ void bfin_serial_rx_dma_timeout(struct bfin_serial_port *uart)
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);
}
--
2.30.2