lockd: close potential race with rapid lockd_up/lockd_down cycle
If lockd_down is called very rapidly after lockd_up returns, then
there is a slim chance that lockd() will never be called. kthread()
will return before calling the function, so we'll end up never
actually calling the cleanup functions for the thread.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index 2169af4..5bd9bf0 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -50,7 +50,7 @@
static DEFINE_MUTEX(nlmsvc_mutex);
static unsigned int nlmsvc_users;
static struct task_struct *nlmsvc_task;
-static struct svc_serv *nlmsvc_serv;
+static struct svc_rqst *nlmsvc_rqst;
int nlmsvc_grace_period;
unsigned long nlmsvc_timeout;
@@ -194,20 +194,11 @@
svc_process(rqstp);
}
-
flush_signals(current);
if (nlmsvc_ops)
nlmsvc_invalidate_all();
nlm_shutdown_hosts();
-
unlock_kernel();
-
- nlmsvc_task = NULL;
- nlmsvc_serv = NULL;
-
- /* Exit the RPC thread */
- svc_exit_thread(rqstp);
-
return 0;
}
@@ -254,16 +245,15 @@
lockd_up(int proto) /* Maybe add a 'family' option when IPv6 is supported ?? */
{
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_serv) {
+ if (nlmsvc_rqst) {
if (proto)
- error = make_socks(nlmsvc_serv, proto);
+ error = make_socks(nlmsvc_rqst->rq_server, proto);
goto out;
}
@@ -288,9 +278,10 @@
/*
* 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);
+ nlmsvc_rqst = svc_prepare_thread(serv, &serv->sv_pools[0]);
+ if (IS_ERR(nlmsvc_rqst)) {
+ error = PTR_ERR(nlmsvc_rqst);
+ nlmsvc_rqst = NULL;
printk(KERN_WARNING
"lockd_up: svc_rqst allocation failed, error=%d\n",
error);
@@ -298,16 +289,15 @@
}
svc_sock_update_bufs(serv);
- nlmsvc_serv = rqstp->rq_server;
- nlmsvc_task = kthread_run(lockd, rqstp, serv->sv_name);
+ nlmsvc_task = kthread_run(lockd, nlmsvc_rqst, serv->sv_name);
if (IS_ERR(nlmsvc_task)) {
error = PTR_ERR(nlmsvc_task);
+ svc_exit_thread(nlmsvc_rqst);
nlmsvc_task = NULL;
- nlmsvc_serv = NULL;
+ nlmsvc_rqst = NULL;
printk(KERN_WARNING
"lockd_up: kthread_run failed, error=%d\n", error);
- svc_exit_thread(rqstp);
goto destroy_and_out;
}
@@ -346,6 +336,9 @@
BUG();
}
kthread_stop(nlmsvc_task);
+ svc_exit_thread(nlmsvc_rqst);
+ nlmsvc_task = NULL;
+ nlmsvc_rqst = NULL;
out:
mutex_unlock(&nlmsvc_mutex);
}