tty/serial/8250: Touch NMI watchdog in wait_for_xmitr

olsajiri · gregkh · commit 54f19b4a6791 · 2016-09-22T11:45:08.000+02:00
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@redhat.com> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git 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 */

Original file line number	Diff line number	Diff line change
`@@ -1982,6 +1982,7 @@ static void wait_for_xmitr(struct uart_8250_port *up, int bits)`
`1982`	`1982`	`if (--tmout == 0)`
`1983`	`1983`	`break;`
`1984`	`1984`	`udelay(1);`
	`1985`	`+ touch_nmi_watchdog();`
`1985`	`1986`	`}`
`1986`	`1987`
`1987`	`1988`	`/* Wait up to 1s for flow control if necessary */`