*: 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, 3 deletions

diff --git a/ripngd/ripng_interface.c b/ripngd/ripng_interface.c
index 1ac9e40f67..dbffa1a88a 100644
--- a/ripngd/ripng_interface.c
+++ b/ripngd/ripng_interface.c
@@ -761,9 +761,8 @@ ripng_enable_apply (struct interface *ifp)
 	    zlog_debug ("RIPng turn on %s", ifp->name);
 
 	  /* Add interface wake up thread. */
-	  if (! ri->t_wakeup)
-	    ri->t_wakeup = thread_add_timer (master, ripng_interface_wakeup,
-					     ifp, 1);
+	  thread_add_timer(master, ripng_interface_wakeup, ifp, 1,
+                           &ri->t_wakeup);
 
 	  ripng_connect_set (ifp, 1);
 	}