USB: fix usb open suspend race in cdc-acm

this fixes a race between open and disconnect in the CDC ACM driver.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 5 insertions, 5 deletions

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index bcc42136c93f..0147ea39340e 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -496,13 +496,10 @@ static int acm_tty_open(struct tty_struct *tty, struct file *filp)
            otherwise it is scheduled, and with high data rates data can get lost. */
         tty->low_latency = 1;
 
-        if (usb_autopm_get_interface(acm->control)) {
-                mutex_unlock(&open_mutex);
-                return -EIO;
-        }
+        if (usb_autopm_get_interface(acm->control) < 0)
+                goto early_bail;
 
         mutex_lock(&acm->mutex);
-        mutex_unlock(&open_mutex);
         if (acm->used++) {
                 usb_autopm_put_interface(acm->control);
                 goto done;
@@ -536,6 +533,7 @@ static int acm_tty_open(struct tty_struct *tty, struct file *filp)
 done:
 err_out:
         mutex_unlock(&acm->mutex);
+        mutex_unlock(&open_mutex);
         return rv;
 
 full_bailout:
@@ -544,6 +542,8 @@ bail_out:
         usb_autopm_put_interface(acm->control);
         acm->used--;
         mutex_unlock(&acm->mutex);
+early_bail:
+        mutex_unlock(&open_mutex);
         return -EIO;
 }