Merge tag 'nfsd-4.21' of git://linux-nfs.org/~bfields/linux

Pull nfsd updates from Bruce Fields:
 "Thanks to Vasily Averin for fixing a use-after-free in the
  containerized NFSv4.2 client, and cleaning up some convoluted
  backchannel server code in the process.

  Otherwise, miscellaneous smaller bugfixes and cleanup"

* tag 'nfsd-4.21' of git://linux-nfs.org/~bfields/linux: (25 commits)
  nfs: fixed broken compilation in nfs_callback_up_net()
  nfs: minor typo in nfs4_callback_up_net()
  sunrpc: fix debug message in svc_create_xprt()
  sunrpc: make visible processing error in bc_svc_process()
  sunrpc: remove unused xpo_prep_reply_hdr callback
  sunrpc: remove svc_rdma_bc_class
  sunrpc: remove svc_tcp_bc_class
  sunrpc: remove unused bc_up operation from rpc_xprt_ops
  sunrpc: replace svc_serv->sv_bc_xprt by boolean flag
  sunrpc: use-after-free in svc_process_common()
  sunrpc: use SVC_NET() in svcauth_gss_* functions
  nfsd: drop useless LIST_HEAD
  lockd: Show pid of lockd for remote locks
  NFSD remove OP_CACHEME from 4.2 op_flags
  nfsd: Return EPERM, not EACCES, in some SETATTR cases
  sunrpc: fix cache_head leak due to queued request
  nfsd: clean up indentation, increase indentation in switch statement
  svcrdma: Optimize the logic that selects the R_key to invalidate
  nfsd: fix a warning in __cld_pipe_upcall()
  nfsd4: fix crash on writing v4_end_grace before nfsd startup
  ...

1 files changed, 6 insertions, 11 deletions

diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index 9c247fa1e959..5188f9f70c78 100644
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -662,7 +662,7 @@ struct cld_net {
 struct cld_upcall {
 	struct list_head	 cu_list;
 	struct cld_net		*cu_net;
-	struct task_struct	*cu_task;
+	struct completion	 cu_done;
 	struct cld_msg		 cu_msg;
 };
 
@@ -671,23 +671,18 @@ __cld_pipe_upcall(struct rpc_pipe *pipe, struct cld_msg *cmsg)
 {
 	int ret;
 	struct rpc_pipe_msg msg;
+	struct cld_upcall *cup = container_of(cmsg, struct cld_upcall, cu_msg);
 
 	memset(&msg, 0, sizeof(msg));
 	msg.data = cmsg;
 	msg.len = sizeof(*cmsg);
 
-	/*
-	 * Set task state before we queue the upcall. That prevents
-	 * wake_up_process in the downcall from racing with schedule.
-	 */
-	set_current_state(TASK_UNINTERRUPTIBLE);
 	ret = rpc_queue_upcall(pipe, &msg);
 	if (ret < 0) {
-		set_current_state(TASK_RUNNING);
 		goto out;
 	}
 
-	schedule();
+	wait_for_completion(&cup->cu_done);
 
 	if (msg.errno < 0)
 		ret = msg.errno;
@@ -754,7 +749,7 @@ cld_pipe_downcall(struct file *filp, const char __user *src, size_t mlen)
 	if (copy_from_user(&cup->cu_msg, src, mlen) != 0)
 		return -EFAULT;
 
-	wake_up_process(cup->cu_task);
+	complete(&cup->cu_done);
 	return mlen;
 }
 
@@ -769,7 +764,7 @@ cld_pipe_destroy_msg(struct rpc_pipe_msg *msg)
 	if (msg->errno >= 0)
 		return;
 
-	wake_up_process(cup->cu_task);
+	complete(&cup->cu_done);
 }
 
 static const struct rpc_pipe_ops cld_upcall_ops = {
@@ -900,7 +895,7 @@ restart_search:
 			goto restart_search;
 		}
 	}
-	new->cu_task = current;
+	init_completion(&new->cu_done);
 	new->cu_msg.cm_vers = CLD_UPCALL_VERSION;
 	put_unaligned(cn->cn_xid++, &new->cu_msg.cm_xid);
 	new->cu_net = cn;