SUNRPC: change svc_recv() to return void.

svc_recv() currently returns a 0 on success or one of two errors:
 - -EAGAIN means no message was successfully received
 - -EINTR means the thread has been told to stop

Previously nfsd would stop as the result of a signal as well as
following kthread_stop().  In that case the difference was useful: EINTR
means stop unconditionally.  EAGAIN means stop if kthread_should_stop(),
continue otherwise.

Now threads only exit when kthread_should_stop() so we don't need the
distinction.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/lockd/svc.c

@@ -116,7 +116,6 @@ static void set_grace_period(struct net *net)
 static int
 lockd(void *vrqstp)
 {
-	int		err = 0;
 	struct svc_rqst *rqstp = vrqstp;
 	struct net *net = &init_net;
 	struct lockd_net *ln = net_generic(net, lockd_net_id);
@@ -138,13 +137,7 @@ lockd(void *vrqstp)
 
 		timeout = nlmsvc_retry_blocked();
 
-		/*
-		 * Find a socket with data available and call its
-		 * recvfrom routine.
-		 */
-		err = svc_recv(rqstp, timeout);
-		if (err == -EAGAIN || err == -EINTR)
-			continue;
+		svc_recv(rqstp, timeout);
 	}
 	if (nlmsvc_ops)
 		nlmsvc_invalidate_all();

fs/nfs/callback.c

@@ -74,19 +74,12 @@ out_err:
 static int
 nfs4_callback_svc(void *vrqstp)
 {
-	int err;
 	struct svc_rqst *rqstp = vrqstp;
 
 	set_freezable();
 
-	while (!kthread_freezable_should_stop(NULL)) {
-		/*
-		 * Listen for a request on the socket
-		 */
-		err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
-		if (err == -EAGAIN || err == -EINTR)
-			continue;
-	}
+	while (!kthread_freezable_should_stop(NULL))
+		svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
 
 	svc_exit_thread(rqstp);
 	return 0;

fs/nfsd/nfssvc.c

@@ -939,7 +939,6 @@ nfsd(void *vrqstp)
 	struct svc_xprt *perm_sock = list_entry(rqstp->rq_server->sv_permsocks.next, typeof(struct svc_xprt), xpt_list);
 	struct net *net = perm_sock->xpt_net;
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
-	int err;
 
 	/* At this point, the thread shares current->fs
 	 * with the init process. We need to create files with the
@@ -958,19 +957,11 @@ nfsd(void *vrqstp)
 	/*
 	 * The main request loop
 	 */
-	for (;;) {
+	while (!kthread_should_stop()) {
 		/* Update sv_maxconn if it has changed */
 		rqstp->rq_server->sv_maxconn = nn->max_connections;
 
-		/*
-		 * Find a socket with data available and call its
-		 * recvfrom routine.
-		 */
-		while ((err = svc_recv(rqstp, 60*60*HZ)) == -EAGAIN)
-			;
-		if (err == -EINTR)
-			break;
-
+		svc_recv(rqstp, 60*60*HZ);
 		validate_process_creds();
 	}
 

include/linux/sunrpc/svcsock.h

@@ -57,7 +57,7 @@ static inline u32 svc_sock_final_rec(struct svc_sock *svsk)
  * Function prototypes.
  */
 void		svc_close_net(struct svc_serv *, struct net *);
-int		svc_recv(struct svc_rqst *, long);
+void		svc_recv(struct svc_rqst *, long);
 void		svc_send(struct svc_rqst *rqstp);
 void		svc_drop(struct svc_rqst *);
 void		svc_sock_update_bufs(struct svc_serv *serv);

net/sunrpc/svc_xprt.c

@@ -679,7 +679,7 @@ static void svc_check_conn_limits(struct svc_serv *serv)
 	}
 }
 
-static int svc_alloc_arg(struct svc_rqst *rqstp)
+static bool svc_alloc_arg(struct svc_rqst *rqstp)
 {
 	struct svc_serv *serv = rqstp->rq_server;
 	struct xdr_buf *arg = &rqstp->rq_arg;
@@ -704,7 +704,7 @@ static int svc_alloc_arg(struct svc_rqst *rqstp)
 		set_current_state(TASK_IDLE);
 		if (kthread_should_stop()) {
 			set_current_state(TASK_RUNNING);
-			return -EINTR;
+			return false;
 		}
 		trace_svc_alloc_arg_err(pages, ret);
 		memalloc_retry_wait(GFP_KERNEL);
@@ -723,7 +723,7 @@ static int svc_alloc_arg(struct svc_rqst *rqstp)
 	arg->tail[0].iov_len = 0;
 
 	rqstp->rq_xid = xdr_zero;
-	return 0;
+	return true;
 }
 
 static bool
@@ -785,8 +785,8 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout)
 		percpu_counter_inc(&pool->sp_threads_timedout);
 
 	if (kthread_should_stop())
-		return ERR_PTR(-EINTR);
-	return ERR_PTR(-EAGAIN);
+		return NULL;
+	return NULL;
 out_found:
 	/* Normally we will wait up to 5 seconds for any required
 	 * cache information to be provided.
@@ -868,32 +868,27 @@ out:
  * organised not to touch any cachelines in the shared svc_serv
  * structure, only cachelines in the local svc_pool.
  */
-int svc_recv(struct svc_rqst *rqstp, long timeout)
+void svc_recv(struct svc_rqst *rqstp, long timeout)
 {
 	struct svc_xprt		*xprt = NULL;
 	struct svc_serv		*serv = rqstp->rq_server;
-	int			len, err;
+	int			len;
 
-	err = svc_alloc_arg(rqstp);
-	if (err)
+	if (!svc_alloc_arg(rqstp))
 		goto out;
 
 	try_to_freeze();
 	cond_resched();
-	err = -EINTR;
 	if (kthread_should_stop())
 		goto out;
 
 	xprt = svc_get_next_xprt(rqstp, timeout);
-	if (IS_ERR(xprt)) {
-		err = PTR_ERR(xprt);
+	if (!xprt)
 		goto out;
-	}
 
 	len = svc_handle_xprt(rqstp, xprt);
 
 	/* No data, incomplete (TCP) read, or accept() */
-	err = -EAGAIN;
 	if (len <= 0)
 		goto out_release;
 
@@ -907,12 +902,11 @@ int svc_recv(struct svc_rqst *rqstp, long timeout)
 		serv->sv_stats->netcnt++;
 	rqstp->rq_stime = ktime_get();
 	svc_process(rqstp);
-	return 0;
+out:
+	return;
 out_release:
 	rqstp->rq_res.len = 0;
 	svc_xprt_release(rqstp);
-out:
-	return err;
 }
 EXPORT_SYMBOL_GPL(svc_recv);