From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sonic Zhang Subject: [PATCH] serial: bfin-uart: avoid dead lock in rx irq handler in smp kernel Date: Wed, 7 Nov 2012 13:27:56 +0800 Message-ID: <1352266076-31683-1-git-send-email-sonic.adi@gmail.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from tx2ehsobe004.messaging.microsoft.com ([65.55.88.14]:23129 "EHLO tx2outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750747Ab2KGF26 (ORCPT ); Wed, 7 Nov 2012 00:28:58 -0500 Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: linux-serial@vger.kernel.org, Greg Kroah-Hartman Cc: uclinux-dist-devel@blackfin.uclinux.org, Steven Miao , Sonic Zhang From: Steven Miao 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 Signed-off-by: Sonic Zhang --- drivers/tty/serial/bfin_uart.c | 7 +++---- 1 files changed, 3 insertions(+), 4 deletions(-) diff --git a/drivers/tty/serial/bfin_uart.c b/drivers/tty/serial/bfin_uart.c index 71c0c09..870a744 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); } -- 1.7.0.4