centos man page for cancel_work_sync

CANCEL_WORK_SYNC(9)						   Driver Basics					       CANCEL_WORK_SYNC(9)

NAME
       cancel_work_sync - cancel a work and wait for it to finish

SYNOPSIS
       bool cancel_work_sync(struct work_struct * work);

ARGUMENTS
       work
	   the work to cancel

DESCRIPTION
       Cancel work and wait for its execution to finish. This function can be used even if the work re-queues itself or migrates to another
       workqueue. On return from this function, work is guaranteed to be not pending or executing on any CPU.

       cancel_work_sync(delayed_work->work) must not be used for delayed_work's. Use cancel_delayed_work_sync instead.

       The caller must ensure that the workqueue on which work was last queued can't be destroyed before this function returns.

RETURNS
       true if work was pending, false otherwise.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014						       CANCEL_WORK_SYNC(9)