[PATCH] USB: One potential problem in gadget/serial.c

It looks like that the gs_serial module maybe sleep with spinlock in gs_close.
Sometimes, system hang when I remove the gs_serial module.

From: Fengwei Yin <xaityyy@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/gadget/serial.c b/drivers/usb/gadget/serial.c
index b35ac6d..65e084a 100644 (file)
--- a/drivers/usb/gadget/serial.c
+++ b/drivers/usb/gadget/serial.c
@@ -890,10 +890,12 @@ static void gs_close(struct tty_struct *tty, struct file *file)
        /* wait for write buffer to drain, or */
        /* at most GS_CLOSE_TIMEOUT seconds */
        if (gs_buf_data_avail(port->port_write_buf) > 0) {
+               spin_unlock_irqrestore(&port->port_lock, flags);
                wait_cond_interruptible_timeout(port->port_write_wait,
                port->port_dev == NULL
                || gs_buf_data_avail(port->port_write_buf) == 0,
                &port->port_lock, flags, GS_CLOSE_TIMEOUT * HZ);
+               spin_lock_irqsave(&port->port_lock, flags);
        }
 
        /* free disconnected port on final close */