Revert "usb: gadget: ffs: Fix BUG when userland exits with submitted AIO transfers"

This reverts commit b4194da3f9087dd38d91b40f9bec42d59ce589a8
since it causes list corruption followed by kernel panic:

Workqueue: adb ffs_aio_cancel_worker
RIP: 0010:__list_add_valid+0x4d/0x70
Call Trace:
insert_work+0x47/0xb0
__queue_work+0xf6/0x400
queue_work_on+0x65/0x70
dwc3_gadget_giveback+0x44/0x50 [dwc3]
dwc3_gadget_ep_dequeue+0x83/0x2d0 [dwc3]
? finish_wait+0x80/0x80
usb_ep_dequeue+0x1e/0x90
process_one_work+0x18c/0x3b0
worker_thread+0x3c/0x390
? process_one_work+0x3b0/0x3b0
kthread+0x11e/0x140
? kthread_create_worker_on_cpu+0x70/0x70
ret_from_fork+0x3a/0x50

This issue is seen with warm reboot stability testing.
Signed-off-by: Shen Jing <jingx.shen@intel.com>
Signed-off-by: Saranya Gopal <saranya.gopal@intel.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/function/f_fs.c

@@ -215,7 +215,6 @@ struct ffs_io_data {
 
 	struct mm_struct *mm;
 	struct work_struct work;
-	struct work_struct cancellation_work;
 
 	struct usb_ep *ep;
 	struct usb_request *req;
@@ -1073,31 +1072,22 @@ ffs_epfile_open(struct inode *inode, struct file *file)
 	return 0;
 }
 
-static void ffs_aio_cancel_worker(struct work_struct *work)
-{
-	struct ffs_io_data *io_data = container_of(work, struct ffs_io_data,
-						   cancellation_work);
-
-	ENTER();
-
-	usb_ep_dequeue(io_data->ep, io_data->req);
-}
-
 static int ffs_aio_cancel(struct kiocb *kiocb)
 {
 	struct ffs_io_data *io_data = kiocb->private;
-	struct ffs_data *ffs = io_data->ffs;
+	struct ffs_epfile *epfile = kiocb->ki_filp->private_data;
 	int value;
 
 	ENTER();
 
-	if (likely(io_data && io_data->ep && io_data->req)) {
-		INIT_WORK(&io_data->cancellation_work, ffs_aio_cancel_worker);
-		queue_work(ffs->io_completion_wq, &io_data->cancellation_work);
-		value = -EINPROGRESS;
-	} else {
+	spin_lock_irq(&epfile->ffs->eps_lock);
+
+	if (likely(io_data && io_data->ep && io_data->req))
+		value = usb_ep_dequeue(io_data->ep, io_data->req);
+	else
 		value = -EINVAL;
-	}
+
+	spin_unlock_irq(&epfile->ffs->eps_lock);
 
 	return value;
 }