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authorLiang Li <liang.li@windriver.com>2013-01-19 17:52:10 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-07-03 11:03:24 -0700
commitdb61e4ec623437237d05b5ab8ce97d9377682de2 (patch)
treeac23384cb73ecfbe95f140b89bd6537658f17ba7
parentc6c46477761504a89d5c68331f3b86fe31b51338 (diff)
pch_uart: fix a deadlock when pch_uart as console
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@windriver.com> Cc: Yijing Wang <wangyijing@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/tty/serial/pch_uart.c29
1 files changed, 22 insertions, 7 deletions
diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
index 73038baa8b67..78c26cace982 100644
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -935,22 +935,37 @@ 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)
- dev_err(&priv->pdev->dev, "Framing Error\n");
+ if (lsr & UART_LSR_FE) {
+ port->icount.frame++;
+ error_msg[i++] = " Framing Error\n";
+ }
- if (lsr & UART_LSR_PE)
- dev_err(&priv->pdev->dev, "Parity Error\n");
+ if (lsr & UART_LSR_PE) {
+ port->icount.parity++;
+ error_msg[i++] = " Parity Error\n";
+ }
- if (lsr & UART_LSR_OE)
- dev_err(&priv->pdev->dev, "Overrun Error\n");
+ if (lsr & UART_LSR_OE) {
+ port->icount.overrun++;
+ error_msg[i++] = " 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)