lkml.org 
[lkml]   [2012]   [Sep]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[ 90/95] pmac_zilog,kdb: Fix console poll hook to return instead of loop
3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jason Wessel <jason.wessel@windriver.com>

commit 38f8eefccf3a23c4058a570fa2938a4f553cf8e0 upstream.

kdb <-> kgdb transitioning does not work properly with this UART
driver because the get character routine loops indefinitely as opposed
to returning NO_POLL_CHAR per the expectation of the KDB I/O driver
API.

The symptom is a kernel hang when trying to switch debug modes.

Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/tty/serial/pmac_zilog.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/pmac_zilog.c b/drivers/tty/serial/pmac_zilog.c
index 654755a..333c8d0 100644
--- a/drivers/tty/serial/pmac_zilog.c
+++ b/drivers/tty/serial/pmac_zilog.c
@@ -1348,10 +1348,16 @@ static int pmz_verify_port(struct uart_port *port, struct serial_struct *ser)
static int pmz_poll_get_char(struct uart_port *port)
{
struct uart_pmac_port *uap = (struct uart_pmac_port *)port;
+ int tries = 2;

- while ((read_zsreg(uap, R0) & Rx_CH_AV) == 0)
- udelay(5);
- return read_zsdata(uap);
+ while (tries) {
+ if ((read_zsreg(uap, R0) & Rx_CH_AV) != 0)
+ return read_zsdata(uap);
+ if (tries--)
+ udelay(5);
+ }
+
+ return NO_POLL_CHAR;
}

static void pmz_poll_put_char(struct uart_port *port, unsigned char c)



\
 
 \ /
  Last update: 2012-09-10 02:21    [W:0.325 / U:0.080 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site