NFSv4: Fix callback server shutdown

We want to use kthread_stop() in order to ensure the threads are
shut down before we tear down the nfs_callback_info in nfs_callback_down.

Tested-and-reviewed-by: Kinglong Mee <kinglongmee@gmail.com>
Reported-by: Kinglong Mee <kinglongmee@gmail.com>
Fixes: bb6aeba736ba9 ("NFSv4.x: Switch to using svc_set_num_threads()...")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
index c5e27eb..73a1f92 100644 (file)
--- a/fs/nfs/callback.c
+++ b/fs/nfs/callback.c
@@ -76,7 +76,10 @@ nfs4_callback_svc(void *vrqstp)
 
        set_freezable();
 
-       while (!kthread_should_stop()) {
+       while (!kthread_freezable_should_stop(NULL)) {
+
+               if (signal_pending(current))
+                       flush_signals(current);
                /*
                 * Listen for a request on the socket
                 */
@@ -85,6 +88,8 @@ nfs4_callback_svc(void *vrqstp)
                        continue;
                svc_process(rqstp);
        }
+       svc_exit_thread(rqstp);
+       module_put_and_exit(0);
        return 0;
 }
 
@@ -103,9 +108,10 @@ nfs41_callback_svc(void *vrqstp)
 
        set_freezable();
 
-       while (!kthread_should_stop()) {
-               if (try_to_freeze())
-                       continue;
+       while (!kthread_freezable_should_stop(NULL)) {
+
+               if (signal_pending(current))
+                       flush_signals(current);
 
                prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE);
                spin_lock_bh(&serv->sv_cb_lock);
@@ -121,11 +127,13 @@ nfs41_callback_svc(void *vrqstp)
                                error);
                } else {
                        spin_unlock_bh(&serv->sv_cb_lock);
-                       schedule();
+                       if (!kthread_should_stop())
+                               schedule();
                        finish_wait(&serv->sv_cb_waitq, &wq);
                }
-               flush_signals(current);
        }
+       svc_exit_thread(rqstp);
+       module_put_and_exit(0);
        return 0;
 }
 
@@ -221,14 +229,14 @@ err_bind:
 static struct svc_serv_ops nfs40_cb_sv_ops = {
        .svo_function           = nfs4_callback_svc,
        .svo_enqueue_xprt       = svc_xprt_do_enqueue,
-       .svo_setup              = svc_set_num_threads,
+       .svo_setup              = svc_set_num_threads_sync,
        .svo_module             = THIS_MODULE,
 };
 #if defined(CONFIG_NFS_V4_1)
 static struct svc_serv_ops nfs41_cb_sv_ops = {
        .svo_function           = nfs41_callback_svc,
        .svo_enqueue_xprt       = svc_xprt_do_enqueue,
-       .svo_setup              = svc_set_num_threads,
+       .svo_setup              = svc_set_num_threads_sync,
        .svo_module             = THIS_MODULE,
 };
 

diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 6ef19cf..9463102 100644 (file)
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -473,6 +473,7 @@ void                   svc_pool_map_put(void);
 struct svc_serv *  svc_create_pooled(struct svc_program *, unsigned int,
                        struct svc_serv_ops *);
 int               svc_set_num_threads(struct svc_serv *, struct svc_pool *, int);
+int               svc_set_num_threads_sync(struct svc_serv *, struct svc_pool *, int);
 int               svc_pool_stats_open(struct svc_serv *serv, struct file *file);
 void              svc_destroy(struct svc_serv *);
 void              svc_shutdown_net(struct svc_serv *, struct net *);

diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index 98dc33a..bc0f5a0 100644 (file)
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -795,6 +795,44 @@ svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
 }
 EXPORT_SYMBOL_GPL(svc_set_num_threads);
 
+/* destroy old threads */
+static int
+svc_stop_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
+{
+       struct task_struct *task;
+       unsigned int state = serv->sv_nrthreads-1;
+
+       /* destroy old threads */
+       do {
+               task = choose_victim(serv, pool, &state);
+               if (task == NULL)
+                       break;
+               kthread_stop(task);
+               nrservs++;
+       } while (nrservs < 0);
+       return 0;
+}
+
+int
+svc_set_num_threads_sync(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
+{
+       if (pool == NULL) {
+               /* The -1 assumes caller has done a svc_get() */
+               nrservs -= (serv->sv_nrthreads-1);
+       } else {
+               spin_lock_bh(&pool->sp_lock);
+               nrservs -= pool->sp_nrthreads;
+               spin_unlock_bh(&pool->sp_lock);
+       }
+
+       if (nrservs > 0)
+               return svc_start_kthreads(serv, pool, nrservs);
+       if (nrservs < 0)
+               return svc_stop_kthreads(serv, pool, nrservs);
+       return 0;
+}
+EXPORT_SYMBOL_GPL(svc_set_num_threads_sync);
+
 /*
  * Called from a server thread as it's exiting. Caller must hold the "service
  * mutex" for the service.