From 54f19b4a679149130f78413c421a5780e90a9d0a Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 21 Sep 2016 16:43:15 +0200 Subject: [PATCH] tty/serial/8250: Touch NMI watchdog in wait_for_xmitr 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 --- --- #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 Signed-off-by: Jiri Olsa Signed-off-by: Greg Kroah-Hartman --- 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 ae3a104..28d29fa 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -1982,6 +1982,7 @@ 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