This is a note to let you know that I've just added the patch titled
pch_uart: fix a deadlock when pch_uart as console
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pch_uart-fix-a-deadlock-when-pch_uart-as-console.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 384e301e3519599b000c1a2ecd938b533fc15d85 Mon Sep 17 00:00:00 2001
From: Liang Li <[email protected]>
Date: Sat, 19 Jan 2013 17:52:10 +0800
Subject: pch_uart: fix a deadlock when pch_uart as console
From: Liang Li <[email protected]>
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 <[email protected]>
Cc: Yijing Wang <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/tty/serial/pch_uart.c | 33 ++++++++++++++++++++++++---------
1 file changed, 24 insertions(+), 9 deletions(-)
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -1034,22 +1034,37 @@ static unsigned int dma_handle_tx(struct
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_PE)
- dev_err(&priv->pdev->dev, "Parity Error\n");
-
- if (lsr & UART_LSR_OE)
- dev_err(&priv->pdev->dev, "Overrun Error\n");
+ if (lsr & UART_LSR_FE) {
+ port->icount.frame++;
+ error_msg[i++] = " Framing Error\n";
+ }
+
+ if (lsr & UART_LSR_PE) {
+ port->icount.parity++;
+ error_msg[i++] = " Parity 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)
Patches currently in stable-queue which might be from [email protected] are
queue-3.4/pch_uart-fix-a-deadlock-when-pch_uart-as-console.patch
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