The pid of the locking daemon can be substituted with a task struct
without a problem. Namely, the value if filled in the context of the lockd
thread and used in lockd_up/lockd_down.
It is possible to save task struct instead and use it to kill the process.
The safety of this operation is guaranteed by the RCU, i.e. task can't
disappear without passing a quiscent state.
Signed-off-by: Denis V. Lunev <[EMAIL PROTECTED]>
---
fs/lockd/svc.c | 38 +++++++++++++++++++++++++-------------
1 files changed, 25 insertions(+), 13 deletions(-)
diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index 82e2192..4979e70 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -48,7 +48,7 @@ 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;
@@ -128,7 +128,8 @@ lockd(struct svc_rqst *rqstp)
/*
* Let our maker know we're running.
*/
- nlmsvc_pid = current->pid;
+ rcu_assign_pointer(nlmsvc_task, current);
+
nlmsvc_serv = rqstp->rq_server;
complete(&lockd_start_done);
@@ -151,7 +152,7 @@ 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 ((nlmsvc_users || !signalled()) && nlmsvc_task == current) {
long timeout = MAX_SCHEDULE_TIMEOUT;
char buf[RPC_MAX_ADDRBUFLEN];
@@ -200,12 +201,12 @@ lockd(struct svc_rqst *rqstp)
* 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_task == NULL || current == nlmsvc_task) {
if (nlmsvc_ops)
nlmsvc_invalidate_all();
nlm_shutdown_hosts();
- nlmsvc_pid = 0;
nlmsvc_serv = NULL;
+ rcu_assign_pointer(nlmsvc_task, NULL);
} else
printk(KERN_DEBUG
"lockd: new process, skipping host shutdown\n");
@@ -273,7 +274,7 @@ lockd_up(int proto) /* Maybe add a 'family' option when
IPv6 is supported ?? */
/*
* Check whether we're already up and running.
*/
- if (nlmsvc_pid) {
+ if (nlmsvc_task != NULL) {
if (proto)
error = make_socks(nlmsvc_serv, proto);
goto out;
@@ -329,38 +330,49 @@ void
lockd_down(void)
{
static int warned;
+ struct task_struct *tsk;
mutex_lock(&nlmsvc_mutex);
+ rcu_read_lock();
+ tsk = rcu_dereference(nlmsvc_task);
if (nlmsvc_users) {
if (--nlmsvc_users)
- goto out;
+ goto out_rcu_unlock;
} else
- printk(KERN_WARNING "lockd_down: no users! pid=%d\n",
nlmsvc_pid);
+ printk(KERN_WARNING "lockd_down: no users! pid=%d\n",
+ task_pid_nr(tsk));
- if (!nlmsvc_pid) {
+ if (tsk == NULL) {
if (warned++ == 0)
printk(KERN_WARNING "lockd_down: no lockd running.\n");
- goto out;
+ goto out_rcu_unlock;
}
warned = 0;
- kill_proc(nlmsvc_pid, SIGKILL, 1);
+ send_sig(SIGKILL, tsk, 1);
+ rcu_read_unlock();
+
/*
* 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) {
+ if (nlmsvc_task != NULL) {
printk(KERN_WARNING
"lockd_down: lockd failed to exit, clearing pid\n");
- nlmsvc_pid = 0;
+ rcu_assign_pointer(nlmsvc_task, NULL);
}
spin_lock_irq(¤t->sighand->siglock);
recalc_sigpending();
spin_unlock_irq(¤t->sighand->siglock);
out:
mutex_unlock(&nlmsvc_mutex);
+ return;
+
+out_rcu_unlock:
+ rcu_read_unlock();
+ goto out;
}
EXPORT_SYMBOL(lockd_down);
--
1.5.3.rc5
--
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