First loop in wait_for_xmitr could also trigger NMI
watchdog in case reading from the port is slow:
PID: 0 TASK: ffffffff819c1460 CPU: 0 COMMAND: "swapper/0"
#0 [ffff88019f405e58] crash_nmi_callback at ffffffff8104d382
#1 [ffff88019f405e68] nmi_handle at ffffffff8168ead9
#2 [ffff88019f405eb0] do_nmi at ffffffff8168ec53
#3 [ffff88019f405ef0] end_repeat_nmi at ffffffff8168df13
[exception RIP: delay_tsc+50]
RIP: ffffffff81325642 RSP: ffff88019f403bb0 RFLAGS: 00000083
RAX: 00000000000005c8 RBX: ffffffff81f83000 RCX: 0000024e4fb88a8b
RDX: 0000024e4fb89053 RSI: 0000000000000000 RDI: 00000000000007d1
RBP: ffff88019f403bb0 R8: 000000000000000a R9: 0000000000000000
R10: 0000000000000000 R11: ffff88019f403ad6 R12: 000000000000250f
R13: 0000000000000020 R14: ffffffff81d360c7 R15: 0000000000000047
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
--- <NMI exception stack> ---
#4 [ffff88019f403bb0] delay_tsc at ffffffff81325642
#5 [ffff88019f403bb8] __const_udelay at ffffffff813255a8
#6 [ffff88019f403bc8] wait_for_xmitr at ffffffff81404390
#7 [ffff88019f403bf0] serial8250_console_putchar at ffffffff8140455c
#8 [ffff88019f403c10] uart_console_write at ffffffff813ff00a
#9 [ffff88019f403c40] serial8250_console_write at ffffffff814044ae
#10 [ffff88019f403c88] call_console_drivers.constprop.15 at ffffffff81086b01
#11 [ffff88019f403cb0] console_unlock at ffffffff8108842f
#12 [ffff88019f403ce8] vprintk_emit at ffffffff81088834
#13 [ffff88019f403d58] vprintk_default at ffffffff81088ba9
#14 [ffff88019f403d68] printk at ffffffff8167f034
Adding touch_nmi_watchdog call to the first loop as well.
Reported-by: Chunyu Hu <chuhu@xxxxxxxxxx>
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
drivers/tty/serial/8250/8250_port.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index bdfa659b9606..f45cb32cf6a7 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1988,6 +1988,7 @@ static void wait_for_xmitr(struct uart_8250_port *up, int bits)
if (--tmout == 0)
break;
udelay(1);
+ touch_nmi_watchdog();
}
/* Wait up to 1s for flow control if necessary */
--
2.7.4
--
To unsubscribe from this list: send the line "unsubscribe linux-serial" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
