Hi Greg,
I'm very sorry this email format problems, please drop this one,
I will resend a correct email to describe this patch later.
Thanks!
Yijing.
On 2013/6/28 11:10, Yijing Wang wrote:
> From: Liang Li <liang.li@xxxxxxxxxxxxx>
>
> commit 384e301e3519599b000c1a2ecd938b533fc15d85 upstream
>
> When we use pch_uart as system console like 'console=ttyPCH0,115200',
> then 'send break' to it. We'll encounter the deadlock on a cpu/core,
> with interrupts disabled on the core. When we happen to have all irqs
> affinity to cpu0 then the deadlock on cpu0 actually deadlock whole
> system.
>
> In pch_uart_interrupt, we have spin_lock_irqsave(&priv->lock, flags)
> then call pch_uart_err_ir when break is received. Then the call to
> dev_err would actually call to pch_console_write then we'll run into
> another spin_lock(&priv->lock), with interrupts disabled.
>
> So in the call sequence lead by pch_uart_interrupt, we should be
> carefully to call functions that will 'print message to console' only
> in case the uart port is not being used as serial console.
>
> Signed-off-by: Liang Li <liang.li@xxxxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> drivers/tty/serial/pch_uart.c | 29 ++++++++++++++++++++++-------
> 1 files changed, 22 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
> index 8b40a1f..10e1a95 100644
> --- a/drivers/tty/serial/pch_uart.c
> +++ b/drivers/tty/serial/pch_uart.c
> @@ -1024,22 +1024,37 @@ static unsigned int dma_handle_tx(struct eg20t_port *priv)
> static void pch_uart_err_ir(struct eg20t_port *priv, unsigned int lsr)
> {
> u8 fcr = ioread8(priv->membase + UART_FCR);
> + struct uart_port *port = &priv->port;
> + struct tty_struct *tty = tty_port_tty_get(&port->state->port);
> + char *error_msg[5] = {};
> + int i = 0;
>
> /* Reset FIFO */
> fcr |= UART_FCR_CLEAR_RCVR;
> iowrite8(fcr, priv->membase + UART_FCR);
>
> if (lsr & PCH_UART_LSR_ERR)
> - dev_err(&priv->pdev->dev, "Error data in FIFO\n");
> + error_msg[i++] = "Error data in FIFO\n";
> +
> + if (lsr & UART_LSR_FE) {
> + port->icount.frame++;
> + error_msg[i++] = " Framing Error\n";
> + }
>
> - if (lsr & UART_LSR_FE)
> - dev_err(&priv->pdev->dev, "Framing Error\n");
> + if (lsr & UART_LSR_PE) {
> + port->icount.parity++;
> + error_msg[i++] = " Parity Error\n";
> + }
>
> - if (lsr & UART_LSR_PE)
> - dev_err(&priv->pdev->dev, "Parity Error\n");
> + if (lsr & UART_LSR_OE) {
> + port->icount.overrun++;
> + error_msg[i++] = " Overrun Error\n";
> + }
>
> - if (lsr & UART_LSR_OE)
> - dev_err(&priv->pdev->dev, "Overrun Error\n");
> + if (tty == NULL) {
> + for (i = 0; error_msg[i] != NULL; i++)
> + dev_err(&priv->pdev->dev, error_msg[i]);
> + }
> }
>
> static irqreturn_t pch_uart_interrupt(int irq, void *dev_id)
>
--
Thanks!
Yijing
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