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Subject[PATCH 5/6] NLM: Convert lockd to use kthreads
Date
Have lockd_up start lockd using kthread_run. With this change,
lockd_down now blocks until lockd actually exits, so there's no longer
need for the waitqueue code at the end of lockd_down. This also means
that only one lockd can be running at a time which simplifies the code
within lockd's main loop.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
fs/lockd/svc.c | 93 ++++++++++++++++++++++++--------------------------------
1 files changed, 40 insertions(+), 53 deletions(-)

diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index 03a83a0..0777a4e 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -25,6 +25,7 @@
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/mutex.h>
+#include <linux/kthread.h>
#include <linux/freezer.h>

#include <linux/sunrpc/types.h>
@@ -48,13 +49,12 @@ EXPORT_SYMBOL(nlmsvc_ops);

static DEFINE_MUTEX(nlmsvc_mutex);
static unsigned int nlmsvc_users;
-static pid_t nlmsvc_pid;
+static struct task_struct *nlmsvc_task;
static struct svc_serv *nlmsvc_serv;
int nlmsvc_grace_period;
unsigned long nlmsvc_timeout;

static DECLARE_COMPLETION(lockd_start_done);
-static DECLARE_WAIT_QUEUE_HEAD(lockd_exit);

/*
* These can be set at insmod time (useful for NFS as root filesystem),
@@ -111,10 +111,11 @@ static inline void clear_grace_period(void)
/*
* This is the lockd kernel thread
*/
-static void
-lockd(struct svc_rqst *rqstp)
+static int
+lockd(void *vrqstp)
{
int err = 0;
+ struct svc_rqst *rqstp = vrqstp;
unsigned long grace_period_expire;

/* Lock module and set up kernel thread */
@@ -122,17 +123,14 @@ lockd(struct svc_rqst *rqstp)
* be holding a reference to this module, so it
* is safe to just claim another reference
*/
- __module_get(THIS_MODULE);
lock_kernel();

/*
* Let our maker know we're running.
*/
- nlmsvc_pid = current->pid;
nlmsvc_serv = rqstp->rq_server;
complete(&lockd_start_done);

- daemonize("lockd");
set_freezable();

/* Process request with signals blocked, but allow SIGKILL. */
@@ -151,7 +149,7 @@ lockd(struct svc_rqst *rqstp)
* NFS mount or NFS daemon has gone away, and we've been sent a
* signal, or else another process has taken over our job.
*/
- while ((nlmsvc_users || !signalled()) && nlmsvc_pid == current->pid) {
+ while (!kthread_should_stop()) {
long timeout = MAX_SCHEDULE_TIMEOUT;
char buf[RPC_MAX_ADDRBUFLEN];

@@ -199,27 +197,18 @@ lockd(struct svc_rqst *rqstp)

flush_signals(current);

- /*
- * Check whether there's a new lockd process before
- * shutting down the hosts and clearing the slot.
- */
- if (!nlmsvc_pid || current->pid == nlmsvc_pid) {
- if (nlmsvc_ops)
- nlmsvc_invalidate_all();
- nlm_shutdown_hosts();
- nlmsvc_pid = 0;
- nlmsvc_serv = NULL;
- } else
- printk(KERN_DEBUG
- "lockd: new process, skipping host shutdown\n");
- wake_up(&lockd_exit);
+ if (nlmsvc_ops)
+ nlmsvc_invalidate_all();
+ nlm_shutdown_hosts();
+ nlmsvc_task = NULL;
+ nlmsvc_serv = NULL;

/* Exit the RPC thread */
svc_exit_thread(rqstp);

/* Release module */
unlock_kernel();
- module_put_and_exit(0);
+ return 0;
}


@@ -269,14 +258,15 @@ static int make_socks(struct svc_serv *serv, int proto)
int
lockd_up(int proto) /* Maybe add a 'family' option when IPv6 is supported ?? */
{
- struct svc_serv * serv;
- int error = 0;
+ struct svc_serv *serv;
+ struct svc_rqst *rqstp;
+ int error = 0;

mutex_lock(&nlmsvc_mutex);
/*
* Check whether we're already up and running.
*/
- if (nlmsvc_pid) {
+ if (nlmsvc_task) {
if (proto)
error = make_socks(nlmsvc_serv, proto);
goto out;
@@ -303,11 +293,24 @@ lockd_up(int proto) /* Maybe add a 'family' option when IPv6 is supported ?? */
/*
* Create the kernel thread and wait for it to start.
*/
+ rqstp = svc_prepare_thread(serv, &serv->sv_pools[0]);
+ if (IS_ERR(rqstp)) {
+ error = PTR_ERR(rqstp);
+ printk(KERN_WARNING
+ "lockd_up: svc_rqst allocation failed, error=%d\n",
+ error);
+ goto destroy_and_out;
+ }
+
+ svc_sock_update_bufs(serv);
init_completion(&lockd_start_done);
- error = svc_create_thread(lockd, serv);
- if (error) {
+ nlmsvc_task = kthread_run(lockd, rqstp, serv->sv_name);
+ if (IS_ERR(nlmsvc_task)) {
+ error = PTR_ERR(nlmsvc_task);
+ nlmsvc_task = NULL;
printk(KERN_WARNING
- "lockd_up: create thread failed, error=%d\n", error);
+ "lockd_up: kthread_run failed, error=%d\n", error);
+ svc_exit_thread(rqstp);
goto destroy_and_out;
}
wait_for_completion(&lockd_start_done);
@@ -332,37 +335,21 @@ EXPORT_SYMBOL(lockd_up);
void
lockd_down(void)
{
- static int warned;
-
mutex_lock(&nlmsvc_mutex);
if (nlmsvc_users) {
if (--nlmsvc_users)
goto out;
- } else
- printk(KERN_WARNING "lockd_down: no users! pid=%d\n", nlmsvc_pid);
-
- if (!nlmsvc_pid) {
- if (warned++ == 0)
- printk(KERN_WARNING "lockd_down: no lockd running.\n");
- goto out;
+ } else {
+ printk(KERN_ERR "lockd_down: no users! task=%p\n",
+ nlmsvc_task);
+ BUG();
}
- warned = 0;

- kill_proc(nlmsvc_pid, SIGKILL, 1);
- /*
- * Wait for the lockd process to exit, but since we're holding
- * the lockd semaphore, we can't wait around forever ...
- */
- clear_thread_flag(TIF_SIGPENDING);
- interruptible_sleep_on_timeout(&lockd_exit, HZ);
- if (nlmsvc_pid) {
- printk(KERN_WARNING
- "lockd_down: lockd failed to exit, clearing pid\n");
- nlmsvc_pid = 0;
+ if (!nlmsvc_task) {
+ printk(KERN_ERR "lockd_down: no lockd running.\n");
+ BUG();
}
- spin_lock_irq(&current->sighand->siglock);
- recalc_sigpending();
- spin_unlock_irq(&current->sighand->siglock);
+ kthread_stop(nlmsvc_task);
out:
mutex_unlock(&nlmsvc_mutex);
}
--
1.5.3.3


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