From: Steven Miao Date: Wed, 7 Nov 2012 05:27:56 +0000 (+0800) Subject: serial: bfin-uart: avoid dead lock in rx irq handler in smp kernel X-Git-Tag: next-20121205~28^2~68 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=9642dbe73c8a;p=karo-tx-linux.git 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 Signed-off-by: Sonic Zhang Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/tty/serial/bfin_uart.c b/drivers/tty/serial/bfin_uart.c index 9242d56ba267..ca64c4a83ce0 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); }