USB: cdc-acm: fix possible deadlock with multiple openers
The lock must be dropped before usb_autopm_interface_put() is called
Signed-off-by: Oliver Neukum <oliver@neukum.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
BUG=chrome-os-partner:3143
TEST=run power_Resume test in tight loops on Alex.
Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
Review URL: http://codereview.chromium.org/6820034
Change-Id: Ic0e9c134b803393c66dbec7d4a66e2b7af5ceae4
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 5fb3117..fc74de7 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -556,7 +556,7 @@
acm = acm_table[tty->index];
if (!acm || !acm->dev)
- goto err_out;
+ goto out;
else
rv = 0;
@@ -572,8 +572,9 @@
mutex_lock(&acm->mutex);
if (acm->port.count++) {
+ mutex_unlock(&acm->mutex);
usb_autopm_put_interface(acm->control);
- goto done;
+ goto out;
}
acm->ctrlurb->dev = acm->dev;
@@ -602,18 +603,18 @@
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:
+out:
mutex_unlock(&open_mutex);
return rv;
full_bailout:
usb_kill_urb(acm->ctrlurb);
bail_out:
- usb_autopm_put_interface(acm->control);
acm->port.count--;
mutex_unlock(&acm->mutex);
+ usb_autopm_put_interface(acm->control);
early_bail:
mutex_unlock(&open_mutex);
tty_port_tty_set(&acm->port, NULL);
