usb: gadget: Use completion interface instead of open coding it

ep_io() uses a completion on stack and open codes the waiting with:

  wait_event_interruptible (done.wait, done.done);
and
  wait_event (done.wait, done.done);

This waits in non-exclusive mode for complete(), but there is no reason to
do so because the completion can only be waited for by the task itself and
complete() wakes exactly one exlusive waiter.

Replace the open coded implementation with the corresponding
wait_for_completion*() functions.

No functional change.

Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lkml.kernel.org/r/20200321113241.043380271@linutronix.de

diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c
index b47938dff1a22e11092413b68fd57ae35d2cc2a7..4c3aff987289c470d665fffb117b0f5dffd56657 100644 (file)
--- a/drivers/usb/gadget/legacy/inode.c
+++ b/drivers/usb/gadget/legacy/inode.c
@@ -344,7 +344,7 @@ ep_io (struct ep_data *epdata, void *buf, unsigned len)
        spin_unlock_irq (&epdata->dev->lock);
 
        if (likely (value == 0)) {
-               value = wait_event_interruptible (done.wait, done.done);
+               value = wait_for_completion_interruptible(&done);
                if (value != 0) {
                        spin_lock_irq (&epdata->dev->lock);
                        if (likely (epdata->ep != NULL)) {
@@ -353,7 +353,7 @@ ep_io (struct ep_data *epdata, void *buf, unsigned len)
                                usb_ep_dequeue (epdata->ep, epdata->req);
                                spin_unlock_irq (&epdata->dev->lock);
 
-                               wait_event (done.wait, done.done);
+                               wait_for_completion(&done);
                                if (epdata->status == -ECONNRESET)
                                        epdata->status = -EINTR;
                        } else {