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: <none>/-1, .owner_cpu: 0
Pid: 1, comm: swapper Not tainted 3.0.0-rc2+ #67
Call Trace:
[<c1289663>] spin_bug+0xa3/0xf0
[<c12897ad>] do_raw_spin_lock+0x7d/0x150
[<c14963de>] _raw_spin_lock_irqsave+0x4e/0x60
[<c102f2bb>] __wake_up+0x1b/0x50
[<c12d3715>] serial_m3110_con_write+0x55/0x60
[<c1041575>] __call_console_drivers+0x75/0x90
[<c10415d9>] _call_console_drivers+0x49/0x80
[<c1041baa>] console_unlock+0xca/0x1f0
[<c10420ef>] vprintk+0x18f/0x4f0
[<c14928a3>] printk+0x18/0x1a
[<c1042730>] register_console+0x2e0/0x350
[<c12d098e>] uart_add_one_port+0x33e/0x3d0
[<c1485ba6>] serial_m3110_probe+0x1c2/0x1df
[<c1303db7>] spi_drv_probe+0x17/0x20
...
Fix this by initializing the waitqueue before the main thread is
created.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/tty/serial/mrst_max3110.c b/drivers/tty/serial/mrst_max3110.c
index 3be1b0d..a764bf9 100644
--- a/drivers/tty/serial/mrst_max3110.c
+++ b/drivers/tty/serial/mrst_max3110.c
@@ -421,7 +421,6 @@
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 @@
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)) {