USB: cdc_acm: Fix race condition when opening tty

If acm_rx_tasklet() gets called before tty_port_block_til_ready()
returns, then bulk IN urbs may not be sent. This fixes it.

Signed-off-by: Henry Gebhardt <gebhardt@astro.uni-tuebingen.de>
Acked-by: Oliver Neukum <oliver@neukum.org>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index e3861b2..b72fa49 100644 (file)
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -609,9 +609,9 @@ static int acm_tty_open(struct tty_struct *tty, struct file *filp)
 
        acm->throttle = 0;
 
 
        acm->throttle = 0;
 

-       tasklet_schedule(&acm->urb_task);

        set_bit(ASYNCB_INITIALIZED, &acm->port.flags);
        rv = tty_port_block_til_ready(&acm->port, tty, filp);
        set_bit(ASYNCB_INITIALIZED, &acm->port.flags);
        rv = tty_port_block_til_ready(&acm->port, tty, filp);

+       tasklet_schedule(&acm->urb_task);

 done:
        mutex_unlock(&acm->mutex);
 err_out:
 done:
        mutex_unlock(&acm->mutex);
 err_out: