*: remove THREAD_ON macros, add nullity check

The way thread.c is written, a caller who wishes to be able to cancel a
thread or avoid scheduling it twice must keep a reference to the thread.
Typically this is done with a long lived pointer whose value is checked
for null in order to know if the thread is currently scheduled.  The
check-and-schedule idiom is so common that several wrapper macros in
thread.h existed solely to provide it.

This patch removes those macros and adds a new parameter to all
thread_add_* functions which is a pointer to the struct thread * to
store the result of a scheduling call. If the value passed is non-null,
the thread will only be scheduled if the value is null. This helps with
consistency.

A Coccinelle spatch has been used to transform code of the form:

  if (t == NULL)
    t = thread_add_* (...)

to the form

  thread_add_* (..., &t)

The THREAD_ON macros have also been transformed to the underlying
thread.c calls.

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/lib/workqueue.c b/lib/workqueue.c
index 51017b34ea..3d481aa899 100644
--- a/lib/workqueue.c
+++ b/lib/workqueue.c
@@ -126,8 +126,8 @@ work_queue_schedule (struct work_queue *wq, unsigned int delay)
        && (wq->thread == NULL)
        && (listcount (wq->items) > 0) )
     {
-      wq->thread = thread_add_background (wq->master, work_queue_run, 
-                                          wq, delay);
+      wq->thread = thread_add_background(wq->master, work_queue_run, wq,
+                                         delay, NULL);
       /* set thread yield time, if needed */
       if (wq->thread && wq->spec.yield != THREAD_YIELD_TIME_SLOT)
         thread_set_yield_time (wq->thread, wq->spec.yield);