*: 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, 13 insertions, 9 deletions

diff --git a/lib/vty.c b/lib/vty.c
index 225a82c2db..a68c5d0bc2 100644
--- a/lib/vty.c
+++ b/lib/vty.c
@@ -2618,23 +2618,26 @@ vty_event (enum event event, int sock, struct vty *vty)
   switch (event)
     {
     case VTY_SERV:
-      vty_serv_thread = thread_add_read (vty_master, vty_accept, vty, sock);
+      vty_serv_thread = thread_add_read(vty_master, vty_accept, vty, sock,
+                                        NULL);
       vector_set_index (Vvty_serv_thread, sock, vty_serv_thread);
       break;
 #ifdef VTYSH
     case VTYSH_SERV:
-      vty_serv_thread = thread_add_read (vty_master, vtysh_accept, vty, sock);
+      vty_serv_thread = thread_add_read(vty_master, vtysh_accept, vty, sock,
+                                        NULL);
       vector_set_index (Vvty_serv_thread, sock, vty_serv_thread);
       break;
     case VTYSH_READ:
-      vty->t_read = thread_add_read (vty_master, vtysh_read, vty, sock);
+      vty->t_read = thread_add_read(vty_master, vtysh_read, vty, sock, NULL);
       break;
     case VTYSH_WRITE:
-      vty->t_write = thread_add_write (vty_master, vtysh_write, vty, sock);
+      vty->t_write = thread_add_write(vty_master, vtysh_write, vty, sock,
+                                      NULL);
       break;
 #endif /* VTYSH */
     case VTY_READ:
-      vty->t_read = thread_add_read (vty_master, vty_read, vty, sock);
+      vty->t_read = thread_add_read(vty_master, vty_read, vty, sock, NULL);
 
       /* Time out treatment. */
       if (vty->v_timeout)
@@ -2642,12 +2645,12 @@ vty_event (enum event event, int sock, struct vty *vty)
           if (vty->t_timeout)
             thread_cancel (vty->t_timeout);
           vty->t_timeout =
-            thread_add_timer (vty_master, vty_timeout, vty, vty->v_timeout);
+            thread_add_timer(vty_master, vty_timeout, vty, vty->v_timeout,
+                             NULL);
         }
       break;
     case VTY_WRITE:
-      if (! vty->t_write)
-        vty->t_write = thread_add_write (vty_master, vty_flush, vty, sock);
+      thread_add_write(vty_master, vty_flush, vty, sock, &vty->t_write);
       break;
     case VTY_TIMEOUT_RESET:
       if (vty->t_timeout)
@@ -2658,7 +2661,8 @@ vty_event (enum event event, int sock, struct vty *vty)
       if (vty->v_timeout)
         {
           vty->t_timeout =
-            thread_add_timer (vty_master, vty_timeout, vty, vty->v_timeout);
+            thread_add_timer(vty_master, vty_timeout, vty, vty->v_timeout,
+                             NULL);
         }
       break;
     }