*: 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, 7 insertions, 4 deletions

diff --git a/nhrpd/netlink_arp.c b/nhrpd/netlink_arp.c
index 76419a7ff1..2b222e3c5c 100644
--- a/nhrpd/netlink_arp.c
+++ b/nhrpd/netlink_arp.c
@@ -124,7 +124,7 @@ static int netlink_route_recv(struct thread *t)
 		}
 	}
 
-	thread_add_read(master, netlink_route_recv, 0, fd);
+	thread_add_read(master, netlink_route_recv, 0, fd, NULL);
 
 	return 0;
 }
@@ -214,7 +214,8 @@ static int netlink_log_recv(struct thread *t)
 		}
 	}
 
-	THREAD_READ_ON(master, netlink_log_thread, netlink_log_recv, 0, netlink_log_fd);
+	thread_add_read(master, netlink_log_recv, 0, netlink_log_fd,
+			&netlink_log_thread);
 
 	return 0;
 }
@@ -230,7 +231,8 @@ void netlink_set_nflog_group(int nlgroup)
 	if (nlgroup) {
 		netlink_log_fd = znl_open(NETLINK_NETFILTER,  0);
 		netlink_log_register(netlink_log_fd, nlgroup);
-		THREAD_READ_ON(master, netlink_log_thread, netlink_log_recv, 0, netlink_log_fd);
+		thread_add_read(master, netlink_log_recv, 0, netlink_log_fd,
+				&netlink_log_thread);
 	}
 }
 
@@ -238,7 +240,8 @@ int netlink_init(void)
 {
 	netlink_req_fd = znl_open(NETLINK_ROUTE, 0);
 	netlink_listen_fd = znl_open(NETLINK_ROUTE, RTMGRP_NEIGH);
-	thread_add_read(master, netlink_route_recv, 0, netlink_listen_fd);
+	thread_add_read(master, netlink_route_recv, 0, netlink_listen_fd,
+			NULL);
 
 	return 0;
 }