NLM: Convert lockd to use kthreads
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. This also adds a check for kthread_should_stop in the main loop of nlmsvc_retry_blocked and after that function returns. There's no sense continuing to retry blocks if lockd is coming down anyway. Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
This commit is contained in:
Jeff Layton
J. Bruce Fields
parent
7086721f9c
commit
d751a7cd06
2 changed files with 60 additions and 75 deletions
132
fs/lockd/svc.c
132
fs/lockd/svc.c
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@ -25,6 +25,7 @@
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#include <linux/smp.h>
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#include <linux/smp_lock.h>
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#include <linux/mutex.h>
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#include <linux/kthread.h>
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#include <linux/freezer.h>
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#include <linux/sunrpc/types.h>
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@ -48,14 +49,11 @@ EXPORT_SYMBOL(nlmsvc_ops);
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static DEFINE_MUTEX(nlmsvc_mutex);
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static unsigned int nlmsvc_users;
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static pid_t nlmsvc_pid;
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static struct task_struct *nlmsvc_task;
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static struct svc_serv *nlmsvc_serv;
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int nlmsvc_grace_period;
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unsigned long nlmsvc_timeout;
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static DECLARE_COMPLETION(lockd_start_done);
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static DECLARE_WAIT_QUEUE_HEAD(lockd_exit);
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/*
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* These can be set at insmod time (useful for NFS as root filesystem),
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* and also changed through the sysctl interface. -- Jamie Lokier, Aug 2003
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@ -111,35 +109,30 @@ static inline void clear_grace_period(void)
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/*
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* This is the lockd kernel thread
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*/
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static void
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lockd(struct svc_rqst *rqstp)
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static int
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lockd(void *vrqstp)
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{
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int err = 0;
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struct svc_rqst *rqstp = vrqstp;
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unsigned long grace_period_expire;
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/* Lock module and set up kernel thread */
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/* lockd_up is waiting for us to startup, so will
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* be holding a reference to this module, so it
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* is safe to just claim another reference
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*/
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__module_get(THIS_MODULE);
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lock_kernel();
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/*
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* Let our maker know we're running.
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*/
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nlmsvc_pid = current->pid;
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nlmsvc_serv = rqstp->rq_server;
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complete(&lockd_start_done);
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daemonize("lockd");
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/* try_to_freeze() is called from svc_recv() */
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set_freezable();
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/* Process request with signals blocked, but allow SIGKILL. */
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/* Allow SIGKILL to tell lockd to drop all of its locks */
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allow_signal(SIGKILL);
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dprintk("NFS locking service started (ver " LOCKD_VERSION ").\n");
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/*
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* FIXME: it would be nice if lockd didn't spend its entire life
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* running under the BKL. At the very least, it would be good to
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* have someone clarify what it's intended to protect here. I've
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* seen some handwavy posts about posix locking needing to be
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* done under the BKL, but it's far from clear.
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*/
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lock_kernel();
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if (!nlm_timeout)
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nlm_timeout = LOCKD_DFLT_TIMEO;
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nlmsvc_timeout = nlm_timeout * HZ;
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@ -148,10 +141,9 @@ lockd(struct svc_rqst *rqstp)
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/*
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* The main request loop. We don't terminate until the last
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* NFS mount or NFS daemon has gone away, and we've been sent a
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* signal, or else another process has taken over our job.
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* NFS mount or NFS daemon has gone away.
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*/
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while ((nlmsvc_users || !signalled()) && nlmsvc_pid == current->pid) {
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while (!kthread_should_stop()) {
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long timeout = MAX_SCHEDULE_TIMEOUT;
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RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
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@ -161,6 +153,7 @@ lockd(struct svc_rqst *rqstp)
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nlmsvc_invalidate_all();
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grace_period_expire = set_grace_period();
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}
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continue;
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}
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/*
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@ -195,28 +188,19 @@ lockd(struct svc_rqst *rqstp)
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}
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flush_signals(current);
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if (nlmsvc_ops)
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nlmsvc_invalidate_all();
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nlm_shutdown_hosts();
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/*
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* Check whether there's a new lockd process before
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* shutting down the hosts and clearing the slot.
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*/
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if (!nlmsvc_pid || current->pid == nlmsvc_pid) {
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if (nlmsvc_ops)
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nlmsvc_invalidate_all();
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nlm_shutdown_hosts();
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nlmsvc_pid = 0;
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nlmsvc_serv = NULL;
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} else
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printk(KERN_DEBUG
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"lockd: new process, skipping host shutdown\n");
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wake_up(&lockd_exit);
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unlock_kernel();
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nlmsvc_task = NULL;
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nlmsvc_serv = NULL;
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/* Exit the RPC thread */
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svc_exit_thread(rqstp);
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/* Release module */
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unlock_kernel();
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module_put_and_exit(0);
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return 0;
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}
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/*
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@ -261,14 +245,15 @@ static int make_socks(struct svc_serv *serv, int proto)
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int
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lockd_up(int proto) /* Maybe add a 'family' option when IPv6 is supported ?? */
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{
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struct svc_serv * serv;
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int error = 0;
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struct svc_serv *serv;
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struct svc_rqst *rqstp;
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int error = 0;
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mutex_lock(&nlmsvc_mutex);
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/*
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* Check whether we're already up and running.
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*/
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if (nlmsvc_pid) {
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if (nlmsvc_serv) {
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if (proto)
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error = make_socks(nlmsvc_serv, proto);
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goto out;
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@ -295,13 +280,28 @@ lockd_up(int proto) /* Maybe add a 'family' option when IPv6 is supported ?? */
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/*
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* Create the kernel thread and wait for it to start.
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*/
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error = svc_create_thread(lockd, serv);
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if (error) {
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rqstp = svc_prepare_thread(serv, &serv->sv_pools[0]);
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if (IS_ERR(rqstp)) {
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error = PTR_ERR(rqstp);
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printk(KERN_WARNING
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"lockd_up: create thread failed, error=%d\n", error);
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"lockd_up: svc_rqst allocation failed, error=%d\n",
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error);
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goto destroy_and_out;
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}
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svc_sock_update_bufs(serv);
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nlmsvc_serv = rqstp->rq_server;
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nlmsvc_task = kthread_run(lockd, rqstp, serv->sv_name);
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if (IS_ERR(nlmsvc_task)) {
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error = PTR_ERR(nlmsvc_task);
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nlmsvc_task = NULL;
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nlmsvc_serv = NULL;
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printk(KERN_WARNING
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"lockd_up: kthread_run failed, error=%d\n", error);
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svc_exit_thread(rqstp);
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goto destroy_and_out;
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}
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wait_for_completion(&lockd_start_done);
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/*
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* Note: svc_serv structures have an initial use count of 1,
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@ -323,37 +323,21 @@ EXPORT_SYMBOL(lockd_up);
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void
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lockd_down(void)
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{
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static int warned;
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mutex_lock(&nlmsvc_mutex);
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if (nlmsvc_users) {
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if (--nlmsvc_users)
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goto out;
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} else
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printk(KERN_WARNING "lockd_down: no users! pid=%d\n", nlmsvc_pid);
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if (!nlmsvc_pid) {
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if (warned++ == 0)
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printk(KERN_WARNING "lockd_down: no lockd running.\n");
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goto out;
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} else {
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printk(KERN_ERR "lockd_down: no users! task=%p\n",
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nlmsvc_task);
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BUG();
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}
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warned = 0;
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kill_proc(nlmsvc_pid, SIGKILL, 1);
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/*
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* Wait for the lockd process to exit, but since we're holding
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* the lockd semaphore, we can't wait around forever ...
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*/
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clear_thread_flag(TIF_SIGPENDING);
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interruptible_sleep_on_timeout(&lockd_exit, HZ);
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if (nlmsvc_pid) {
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printk(KERN_WARNING
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"lockd_down: lockd failed to exit, clearing pid\n");
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nlmsvc_pid = 0;
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if (!nlmsvc_task) {
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printk(KERN_ERR "lockd_down: no lockd running.\n");
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BUG();
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}
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spin_lock_irq(¤t->sighand->siglock);
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recalc_sigpending();
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spin_unlock_irq(¤t->sighand->siglock);
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kthread_stop(nlmsvc_task);
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out:
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mutex_unlock(&nlmsvc_mutex);
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}
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@ -29,6 +29,7 @@
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#include <linux/sunrpc/svc.h>
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#include <linux/lockd/nlm.h>
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#include <linux/lockd/lockd.h>
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#include <linux/kthread.h>
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#define NLMDBG_FACILITY NLMDBG_SVCLOCK
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@ -887,7 +888,7 @@ nlmsvc_retry_blocked(void)
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unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
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struct nlm_block *block;
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while (!list_empty(&nlm_blocked)) {
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while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
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block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
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if (block->b_when == NLM_NEVER)
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