From e480af09c49736848f749a43dff2c902104f6691 Mon Sep 17 00:00:00 2001 From: Dave Jones Date: Mon, 25 Sep 2006 16:51:26 -0700 Subject: [PATCH] [SERIAL] tickle NMI watchdog on serial output. Serial is _slow_ sometimes. So slow, that the NMI watchdog kicks in. NMI Watchdog detected LOCKUP on CPU2CPU 2 Modules linked in: loop usb_storage md5 ipv6 parport_pc lp parport autofs4 i2c_dev i2c_core rfcomm l2cap bluetooth sunrpc pcdPid: 3138, comm: gpm Not tainted 2.6.11-1.1290_FC4smp RIP: 0010:[] {serial_in+106} RSP: 0018:ffff81003afc3d50 EFLAGS: 00000002 RAX: 0000000000000020 RBX: 0000000000000020 RCX: 0000000000000000 RDX: 00000000000003fd RSI: 0000000000000005 RDI: ffffffff804dcd60 RBP: 00000000000024fc R08: 000000000000000a R09: 0000000000000033 R10: ffff81001beb7c20 R11: 0000000000000020 R12: ffffffff804dcd60 R13: ffffffff804ade76 R14: 000000000000002b R15: 000000000000002c FS: 00002aaaaaac4920(0000) GS:ffffffff804fca00(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00002aaaaabcb000 CR3: 000000003c0d0000 CR4: 00000000000006e0 Process gpm (pid: 3138, threadinfo ffff81003afc2000, task ffff81003eb63780) Stack: ffffffff80275f2e 0000000000000000 ffffffff80448380 0000000000007d6b 000000000000002c fffffffffffffbbf 0000000000000292 0000000000008000 ffffffff80138e8c 0000000000007d97 Call Trace:{serial8250_console_write+270} {__call_console_drivers+76} {release_console_sem+315} {con_open+149} {tty_open+537} {chrdev_open+387} {dentry_open+260} {filp_open+68} {get_unused_fd+227} {sys_open+76} {tracesys+209} Code: 0f b6 c0 c3 66 90 41 57 49 89 f7 41 56 41 be 00 01 00 00 41 console shuts up ... I initially did the patch below a year ago for the Fedora kernel, and have been keeping it up to date since. I recently got the same thing happening on a vanilla kernel, so figured it was time to repost this. Signed-off-by: Dave Jones Acked-by: Alan Cox Signed-off-by: Andrew Morton Signed-off-by: Russell King --- drivers/serial/8250.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c index a07442ffef..0ede0ee642 100644 --- a/drivers/serial/8250.c +++ b/drivers/serial/8250.c @@ -2232,9 +2232,10 @@ static inline void wait_for_xmitr(struct uart_8250_port *up, int bits) /* Wait up to 1s for flow control if necessary */ if (up->port.flags & UPF_CONS_FLOW) { tmout = 1000000; - while (--tmout && - ((serial_in(up, UART_MSR) & UART_MSR_CTS) == 0)) + while (!(serial_in(up, UART_MSR) & UART_MSR_CTS) && --tmout) { udelay(1); + touch_nmi_watchdog(); + } } } -- 2.39.5