[Devel] [PATCH] ipv4/ipvs: Convert to kthread API

[Eric W. Biederman]

From: Eric W. Biederman <ebiederm at xmission.com> - unquoted

Modify startup of ipvs sync threads to use kthread_run
instead of a weird combination of calling kernel_thread
to start a fork_sync_thread whose hole purpose in life was
to call kernel_thread again starting the actually sync thread
which called daemonize.

To use kthread_run I had to move the name calcuation from
sync_thread into start_sync_thread resulting in a small
amount of code motion.

The result is simpler and more maintainable piece of code.

Cc: Wensong Zhang <wensong at linux-vs.org>
Cc: Julian Anastasov <ja at ssi.bg>
Cc: Simon Horman <horms at verge.net.au>
Signed-off-by: Eric W. Biederman <ebiederm at xmission.com>
---
 net/ipv4/ipvs/ip_vs_sync.c |   49 ++++++++++---------------------------------
 1 files changed, 12 insertions(+), 37 deletions(-)

diff --git a/net/ipv4/ipvs/ip_vs_sync.c b/net/ipv4/ipvs/ip_vs_sync.c
index 7ea2d98..c4be9dc 100644
--- a/net/ipv4/ipvs/ip_vs_sync.c
+++ b/net/ipv4/ipvs/ip_vs_sync.c
@@ -29,6 +29,7 @@
 #include <linux/in.h>
 #include <linux/igmp.h>                 /* for ip_mc_join_group */
 #include <linux/udp.h>
+#include <linux/kthread.h>
 
 #include <net/ip.h>
 #include <net/sock.h>
@@ -750,34 +751,23 @@ static int sync_thread(void *startup)
 	DECLARE_WAITQUEUE(wait, current);
 	mm_segment_t oldmm;
 	int state;
-	const char *name;
 
 	/* increase the module use count */
 	ip_vs_use_count_inc();
 
-	if (ip_vs_sync_state & IP_VS_STATE_MASTER && !sync_master_pid) {
+	if (ip_vs_sync_state & IP_VS_STATE_MASTER && !sync_master_pid)
 		state = IP_VS_STATE_MASTER;
-		name = "ipvs_syncmaster";
-	} else if (ip_vs_sync_state & IP_VS_STATE_BACKUP && !sync_backup_pid) {
+	else if (ip_vs_sync_state & IP_VS_STATE_BACKUP && !sync_backup_pid)
 		state = IP_VS_STATE_BACKUP;
-		name = "ipvs_syncbackup";
-	} else {
+	else {
 		IP_VS_BUG();
 		ip_vs_use_count_dec();
 		return -EINVAL;
 	}
 
-	daemonize(name);
-
 	oldmm = get_fs();
 	set_fs(KERNEL_DS);
 
-	/* Block all signals */
-	spin_lock_irq(&current->sighand->siglock);
-	siginitsetinv(&current->blocked, 0);
-	recalc_sigpending();
-	spin_unlock_irq(&current->sighand->siglock);
-
 	/* set the maximum length of sync message */
 	set_sync_mesg_maxlen(state);
 
@@ -815,29 +805,11 @@ static int sync_thread(void *startup)
 	return 0;
 }
 
-
-static int fork_sync_thread(void *startup)
-{
-	pid_t pid;
-
-	/* fork the sync thread here, then the parent process of the
-	   sync thread is the init process after this thread exits. */
-  repeat:
-	if ((pid = kernel_thread(sync_thread, startup, 0)) < 0) {
-		IP_VS_ERR("could not create sync_thread due to %d... "
-			  "retrying.\n", pid);
-		msleep_interruptible(1000);
-		goto repeat;
-	}
-
-	return 0;
-}
-
-
 int start_sync_thread(int state, char *mcast_ifn, __u8 syncid)
 {
 	DECLARE_COMPLETION_ONSTACK(startup);
-	pid_t pid;
+	struct task_struct *task;
+	const char *name;
 
 	if ((state == IP_VS_STATE_MASTER && sync_master_pid) ||
 	    (state == IP_VS_STATE_BACKUP && sync_backup_pid))
@@ -852,16 +824,19 @@ int start_sync_thread(int state, char *mcast_ifn, __u8 syncid)
 		strlcpy(ip_vs_master_mcast_ifn, mcast_ifn,
 			sizeof(ip_vs_master_mcast_ifn));
 		ip_vs_master_syncid = syncid;
+		name = "ipvs_syncmaster";
 	} else {
 		strlcpy(ip_vs_backup_mcast_ifn, mcast_ifn,
 			sizeof(ip_vs_backup_mcast_ifn));
 		ip_vs_backup_syncid = syncid;
+		name = "ipvs_syncbackup";
 	}
 
   repeat:
-	if ((pid = kernel_thread(fork_sync_thread, &startup, 0)) < 0) {
-		IP_VS_ERR("could not create fork_sync_thread due to %d... "
-			  "retrying.\n", pid);
+	task = kthread_run(sync_thread, &startup, name);
+	if (IS_ERR(task)) {
+		IP_VS_ERR("could not create sync_thread due to %ld... "
+			  "retrying.\n", PTR_ERR(task));
 		msleep_interruptible(1000);
 		goto repeat;
 	}
-- 
1.5.0.g53756

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