*: 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, 6 insertions, 3 deletions

diff --git a/lib/smux.c b/lib/smux.c
index 370b8f138e..e0db87e4b0 100644
--- a/lib/smux.c
+++ b/lib/smux.c
@@ -1197,13 +1197,16 @@ smux_event (enum smux_event event, int sock)
   switch (event)
     {
     case SMUX_SCHEDULE:
-      smux_connect_thread = thread_add_event (smux_master, smux_connect, NULL, 0);
+      smux_connect_thread = thread_add_event(smux_master, smux_connect, NULL,
+                                             0, NULL);
       break;
     case SMUX_CONNECT:
-      smux_connect_thread = thread_add_timer (smux_master, smux_connect, NULL, 10);
+      smux_connect_thread = thread_add_timer(smux_master, smux_connect, NULL,
+                                             10, NULL);
       break;
     case SMUX_READ:
-      smux_read_thread = thread_add_read (smux_master, smux_read, NULL, sock);
+      smux_read_thread = thread_add_read(smux_master, smux_read, NULL, sock,
+                                         NULL);
       break;
     default:
       break;