USB: cdc-acm: minimise no-suspend window during shutdown
Now that acm_set_control() handles runtime PM properly, the only
remaining reason for the PM operations in shutdown is to clear the
needs_remote_wakeup flag before the final put.
Note that this also means that we now need to grab the write_lock to
prevent racing with resume.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 91fdc29..f038f39 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -590,13 +590,22 @@
struct urb *urb;
struct acm_wb *wb;
int i;
- int pm_err;
dev_dbg(&acm->control->dev, "%s\n", __func__);
- pm_err = usb_autopm_get_interface(acm->control);
acm_set_control(acm, acm->ctrlout = 0);
+ /*
+ * Need to grab write_lock to prevent race with resume, but no need to
+ * hold it due to the tty-port initialised flag.
+ */
+ spin_lock_irq(&acm->write_lock);
+ spin_unlock_irq(&acm->write_lock);
+
+ usb_autopm_get_interface_no_resume(acm->control);
+ acm->control->needs_remote_wakeup = 0;
+ usb_autopm_put_interface(acm->control);
+
for (;;) {
urb = usb_get_from_anchor(&acm->delayed);
if (!urb)
@@ -611,10 +620,6 @@
usb_kill_urb(acm->wb[i].urb);
for (i = 0; i < acm->rx_buflimit; i++)
usb_kill_urb(acm->read_urbs[i]);
-
- acm->control->needs_remote_wakeup = 0;
- if (!pm_err)
- usb_autopm_put_interface(acm->control);
}
static void acm_tty_cleanup(struct tty_struct *tty)