NFSv4: Ensure the callback daemon flushes signals

If the callback daemon is signalled, but is unable to exit because it still
has users, then we need to flush signals. If not, then svc_recv() can
never sleep, and so we hang.
If we flush signals, then we also have to be prepared to resend them when
we want the thread to exit.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
index 2c042f8d70b5835a33b4b7992e6f1d10bda43b02..99d2cfbce863af6d17b2e7eb672a7acc76fbb72e 100644 (file)
--- a/fs/nfs/callback.c
+++ b/fs/nfs/callback.c
@@ -55,7 +55,12 @@ static void nfs_callback_svc(struct svc_rqst *rqstp)
 
        complete(&nfs_callback_info.started);
 
-       while (nfs_callback_info.users != 0 || !signalled()) {
+       for(;;) {
+               if (signalled()) {
+                       if (nfs_callback_info.users == 0)
+                               break;
+                       flush_signals(current);
+               }
                /*
                 * Listen for a request on the socket
                 */
@@ -135,11 +140,13 @@ int nfs_callback_down(void)
 
        lock_kernel();
        down(&nfs_callback_sema);
-       if (--nfs_callback_info.users || nfs_callback_info.pid == 0)
-               goto out;
-       kill_proc(nfs_callback_info.pid, SIGKILL, 1);
-       wait_for_completion(&nfs_callback_info.stopped);
-out:
+       nfs_callback_info.users--;
+       do {
+               if (nfs_callback_info.users != 0 || nfs_callback_info.pid == 0)
+                       break;
+               if (kill_proc(nfs_callback_info.pid, SIGKILL, 1) < 0)
+                       break;
+       } while (wait_for_completion_timeout(&nfs_callback_info.stopped, 5*HZ) == 0);
        up(&nfs_callback_sema);
        unlock_kernel();
        return ret;