From 33b1e6939f5c37ab8e64280fd3d54046607b5c80 Mon Sep 17 00:00:00 2001 From: Mika Westerberg Date: Thu, 23 Jun 2011 13:39:00 +0100 Subject: [PATCH] serial: mrst_max3110: initialize waitqueue earlier The driver went to initialize its waitqueue at the start of the main processing thread. However, it is possible that this thread is not scheduled on a CPU before the write function is called which leads to a following error: BUG: spinlock bad magic on CPU#1, swapper/1 lock: f5f3ebdc, .magic: 00000000, .owner: /-1, .owner_cpu: 0 Pid: 1, comm: swapper Not tainted 3.0.0-rc2+ #67 Call Trace: [] spin_bug+0xa3/0xf0 [] do_raw_spin_lock+0x7d/0x150 [] _raw_spin_lock_irqsave+0x4e/0x60 [] __wake_up+0x1b/0x50 [] serial_m3110_con_write+0x55/0x60 [] __call_console_drivers+0x75/0x90 [] _call_console_drivers+0x49/0x80 [] console_unlock+0xca/0x1f0 [] vprintk+0x18f/0x4f0 [] printk+0x18/0x1a [] register_console+0x2e0/0x350 [] uart_add_one_port+0x33e/0x3d0 [] serial_m3110_probe+0x1c2/0x1df [] spi_drv_probe+0x17/0x20 ... Fix this by initializing the waitqueue before the main thread is created. Signed-off-by: Mika Westerberg Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- drivers/tty/serial/mrst_max3110.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/mrst_max3110.c b/drivers/tty/serial/mrst_max3110.c index 3be1b0dd6f22..a764bf99743b 100644 --- a/drivers/tty/serial/mrst_max3110.c +++ b/drivers/tty/serial/mrst_max3110.c @@ -421,7 +421,6 @@ static int max3110_main_thread(void *_max) int ret = 0; struct circ_buf *xmit = &max->con_xmit; - init_waitqueue_head(wq); pr_info(PR_FMT "start main thread\n"); do { @@ -838,6 +837,8 @@ static int __devinit serial_m3110_probe(struct spi_device *spi) max->con_xmit.head = 0; max->con_xmit.tail = 0; + init_waitqueue_head(&max->wq); + max->main_thread = kthread_run(max3110_main_thread, max, "max3110_main"); if (IS_ERR(max->main_thread)) { -- 2.30.2