[src/trunk]: src/tests/fs/nfs/nfsservice Defer definitely-nonreentrant signal...

[pooka <pooka%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/b3b7ccfce238
branches:  trunk
changeset: 756677:b3b7ccfce238
user:      pooka <pooka%NetBSD.org@localhost>
date:      Wed Jul 28 15:15:22 2010 +0000

description:
Defer definitely-nonreentrant signal handler to thread context.
This protects from rump kernel reentry and makes things not
crash && burn.

diffstat:

 tests/fs/nfs/nfsservice/mountd.c |  36 +++++++++++++++++++++++++++++++++---
 1 files changed, 33 insertions(+), 3 deletions(-)

diffs (85 lines):

diff -r 4383db68bff6 -r b3b7ccfce238 tests/fs/nfs/nfsservice/mountd.c
--- a/tests/fs/nfs/nfsservice/mountd.c  Wed Jul 28 15:12:17 2010 +0000
+++ b/tests/fs/nfs/nfsservice/mountd.c  Wed Jul 28 15:15:22 2010 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: mountd.c,v 1.3 2010/07/27 14:04:47 macallan Exp $       */
+/*     $NetBSD: mountd.c,v 1.4 2010/07/28 15:15:22 pooka Exp $  */
 
 /*
  * Copyright (c) 1989, 1993
@@ -42,7 +42,7 @@
 #if 0
 static char     sccsid[] = "@(#)mountd.c  8.15 (Berkeley) 5/1/95";
 #else
-__RCSID("$NetBSD: mountd.c,v 1.3 2010/07/27 14:04:47 macallan Exp $");
+__RCSID("$NetBSD: mountd.c,v 1.4 2010/07/28 15:15:22 pooka Exp $");
 #endif
 #endif                         /* not lint */
 
@@ -75,6 +75,7 @@
 #include <netdb.h>
 #include <pwd.h>
 #include <netgroup.h>
+#include <pthread.h>
 #include <semaphore.h>
 #include <signal.h>
 #include <stdio.h>
@@ -305,6 +306,31 @@
 }
 
 /*
+ * Make sure mountd signal handler is executed from a thread context
+ * instead of the signal handler.  This avoids the signal handler
+ * ruining our kernel context.
+ */
+static sem_t exportsem;
+static void
+signal_get_exportlist(int sig)
+{
+
+       sem_post(&exportsem);
+}
+
+static void *
+exportlist_thread(void *arg)
+{
+
+       for (;;) {
+               sem_wait(&exportsem);
+               get_exportlist(0);
+       }
+
+       return NULL;
+}
+
+/*
  * Mountd server for NFS mount protocol as described in:
  * NFS: Network File System Protocol Specification, RFC1094, Appendix A
  * The optional arguments are the exports file name
@@ -323,6 +349,7 @@
        int maxrec = RPC_MAXDATASIZE;
        in_port_t forcedport = 0;
        extern sem_t gensem;
+       pthread_t ptdummy;
 
        alloc_fdset();
 
@@ -361,6 +388,9 @@
        argv += optind;
 #endif
 
+       sem_init(&exportsem, 0, 0);
+       pthread_create(&ptdummy, NULL, exportlist_thread, NULL);
+
        grphead = NULL;
        exphead = NULL;
        mlhead = NULL;
@@ -381,7 +411,7 @@
                (void)signal(SIGINT, SIG_IGN);
                (void)signal(SIGQUIT, SIG_IGN);
        }
-       (void)signal(SIGHUP, get_exportlist);
+       (void)signal(SIGHUP, signal_get_exportlist);
        (void)signal(SIGTERM, send_umntall);
        pidfile(NULL);