[ovs-dev] [threads 05/11] ovs-thread: Add support for various thread-related assertions.
Ben Pfaff
blp at nicira.com
Wed Jun 19 20:17:06 UTC 2013
Signed-off-by: Ben Pfaff <blp at nicira.com>
---
lib/command-line.c | 4 ++-
lib/daemon.c | 12 +++-----
lib/ofp-version-opt.c | 3 ++
lib/ovs-thread.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++
lib/ovs-thread.h | 11 ++++++++
lib/process.c | 4 +++
lib/timeval.c | 2 +
lib/util.c | 4 +++
8 files changed, 100 insertions(+), 8 deletions(-)
diff --git a/lib/command-line.c b/lib/command-line.c
index 70b1f4d..7800c0b 100644
--- a/lib/command-line.c
+++ b/lib/command-line.c
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2008, 2009, 2010, 2011 Nicira, Inc.
+ * Copyright (c) 2008, 2009, 2010, 2011, 2013 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -19,6 +19,7 @@
#include <getopt.h>
#include <limits.h>
#include <stdlib.h>
+#include "ovs-thread.h"
#include "util.h"
#include "vlog.h"
@@ -110,6 +111,7 @@ proctitle_init(int argc, char **argv)
{
int i;
+ assert_single_threaded();
if (!argc || !argv[0]) {
/* This situation should never occur, but... */
return;
diff --git a/lib/daemon.c b/lib/daemon.c
index e12bc14..56b32b8 100644
--- a/lib/daemon.c
+++ b/lib/daemon.c
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira, Inc.
+ * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -29,6 +29,7 @@
#include "fatal-signal.h"
#include "dirs.h"
#include "lockfile.h"
+#include "ovs-thread.h"
#include "process.h"
#include "socket-util.h"
#include "timeval.h"
@@ -88,6 +89,7 @@ make_pidfile_name(const char *name)
void
set_pidfile(const char *name)
{
+ assert_single_threaded();
free(pidfile);
pidfile = make_pidfile_name(name);
}
@@ -280,9 +282,7 @@ daemonize(void)
pid_t
fork_and_clean_up(void)
{
- pid_t pid;
-
- pid = fork();
+ pid_t pid = xfork();
if (pid > 0) {
/* Running in parent process. */
fatal_signal_fork();
@@ -290,10 +290,7 @@ fork_and_clean_up(void)
/* Running in child process. */
time_postfork();
lockfile_postfork();
- } else {
- VLOG_FATAL("fork failed (%s)", strerror(errno));
}
-
return pid;
}
@@ -504,6 +501,7 @@ close_standard_fds(void)
void
daemonize_start(void)
{
+ assert_single_threaded();
daemonize_fd = -1;
if (detach) {
diff --git a/lib/ofp-version-opt.c b/lib/ofp-version-opt.c
index 35d79e6..84e83d8 100644
--- a/lib/ofp-version-opt.c
+++ b/lib/ofp-version-opt.c
@@ -1,6 +1,7 @@
#include <config.h>
#include "ofp-util.h"
#include "ofp-version-opt.h"
+#include "ovs-thread.h"
#include "vlog.h"
#include "dynamic-string.h"
@@ -17,12 +18,14 @@ get_allowed_ofp_versions(void)
void
set_allowed_ofp_versions(const char *string)
{
+ assert_single_threaded();
allowed_versions = ofputil_versions_from_string(string);
}
void
mask_allowed_ofp_versions(uint32_t bitmap)
{
+ assert_single_threaded();
allowed_versions &= bitmap;
}
diff --git a/lib/ovs-thread.c b/lib/ovs-thread.c
index d69ec5e..56303f7 100644
--- a/lib/ovs-thread.c
+++ b/lib/ovs-thread.c
@@ -17,7 +17,12 @@
#include <config.h>
#include "ovs-thread.h"
#include <errno.h>
+#include <poll.h>
+#include <stdlib.h>
+#include <unistd.h>
#include "compiler.h"
+#include "poll-loop.h"
+#include "socket-util.h"
#include "util.h"
#ifdef __CHECKER__
@@ -26,6 +31,18 @@
* cut-and-paste. Since "sparse" is just a checker, not a compiler, it
* doesn't matter that we don't define them. */
#else
+#include "vlog.h"
+
+VLOG_DEFINE_THIS_MODULE(ovs_thread);
+
+/* If there is a reason that we cannot fork anymore (unless the fork will be
+ * immediately followed by an exec), then this points to a string that
+ * explains why. */
+static const char *must_not_fork;
+
+/* True if we created any threads beyond the main initial thread. */
+static bool multithreaded;
+
#define XPTHREAD_FUNC1(FUNCTION, PARAM1) \
void \
x##FUNCTION(PARAM1 arg1) \
@@ -100,6 +117,9 @@ xpthread_create(pthread_t *threadp, pthread_attr_t *attr,
pthread_t thread;
int error;
+ forbid_forking("multiple threads exist");
+ multithreaded = true;
+
error = pthread_create(threadp ? threadp : &thread, attr, start, arg);
if (error) {
ovs_abort(error, "pthread_create failed");
@@ -123,4 +143,52 @@ ovsthread_once_done(struct ovsthread_once *once)
atomic_store(&once->done, true);
xpthread_mutex_unlock(&once->mutex);
}
+
+/* Asserts that the process has not yet created any threads (beyond the initial
+ * thread). */
+void
+(assert_single_threaded)(const char *where)
+{
+ if (multithreaded) {
+ VLOG_FATAL("%s: attempted operation not allowed when multithreaded",
+ where);
+ }
+}
+
+/* Forks the current process (checking that this is allowed). Aborts with
+ * VLOG_FATAL if fork() returns an error, and otherwise returns the value
+ * returned by fork(). */
+pid_t
+(xfork)(const char *where)
+{
+ pid_t pid;
+
+ if (must_not_fork) {
+ VLOG_FATAL("%s: attempted to fork but forking not allowed (%s)",
+ where, must_not_fork);
+ }
+
+ pid = fork();
+ if (pid < 0) {
+ VLOG_FATAL("fork failed (%s)", strerror(errno));
+ }
+ return pid;
+}
+
+/* Notes that the process must not call fork() from now on, for the specified
+ * 'reason'. (The process may still fork() if it execs itself immediately
+ * afterward.) */
+void
+forbid_forking(const char *reason)
+{
+ ovs_assert(reason != NULL);
+ must_not_fork = reason;
+}
+
+/* Returns true if the process is allowed to fork, false otherwise. */
+bool
+may_fork(void)
+{
+ return !must_not_fork;
+}
#endif
diff --git a/lib/ovs-thread.h b/lib/ovs-thread.h
index 4779030..10f8b6b 100644
--- a/lib/ovs-thread.h
+++ b/lib/ovs-thread.h
@@ -18,6 +18,8 @@
#define OVS_THREAD_H 1
#include <pthread.h>
+#include <stddef.h>
+#include <sys/types.h>
#include "ovs-atomic.h"
#include "util.h"
@@ -355,5 +357,14 @@ ovsthread_once_start(struct ovsthread_once *once)
#define ovsthread_once_start(ONCE) \
((ONCE)->done ? false : ({ OVS_ACQUIRE(ONCE); true; }))
#endif
+
+void assert_single_threaded(const char *where);
+#define assert_single_threaded() assert_single_threaded(SOURCE_LOCATOR)
+
+pid_t xfork(const char *where);
+#define xfork() xfork(SOURCE_LOCATOR)
+
+void forbid_forking(const char *reason);
+bool may_fork(void);
#endif /* ovs-thread.h */
diff --git a/lib/process.c b/lib/process.c
index 03e00ce..266c90b 100644
--- a/lib/process.c
+++ b/lib/process.c
@@ -28,6 +28,7 @@
#include "dynamic-string.h"
#include "fatal-signal.h"
#include "list.h"
+#include "ovs-thread.h"
#include "poll-loop.h"
#include "signals.h"
#include "socket-util.h"
@@ -71,6 +72,7 @@ process_init(void)
static bool inited;
struct sigaction sa;
+ assert_single_threaded();
if (inited) {
return;
}
@@ -180,6 +182,8 @@ process_start(char **argv, struct process **pp)
pid_t pid;
int error;
+ assert_single_threaded();
+
*pp = NULL;
COVERAGE_INC(process_start);
error = process_prestart(argv);
diff --git a/lib/timeval.c b/lib/timeval.c
index 5ff59bc..4723c56 100644
--- a/lib/timeval.c
+++ b/lib/timeval.c
@@ -30,6 +30,7 @@
#include "fatal-signal.h"
#include "hash.h"
#include "hmap.h"
+#include "ovs-thread.h"
#include "signals.h"
#include "unixctl.h"
#include "util.h"
@@ -297,6 +298,7 @@ time_alarm(unsigned int secs)
long long int now;
long long int msecs;
+ assert_single_threaded();
time_init();
time_refresh();
diff --git a/lib/util.c b/lib/util.c
index cd4019e..2a06461 100644
--- a/lib/util.c
+++ b/lib/util.c
@@ -28,6 +28,7 @@
#include "byte-order.h"
#include "coverage.h"
#include "openvswitch/types.h"
+#include "ovs-thread.h"
#include "vlog.h"
VLOG_DEFINE_THIS_MODULE(util);
@@ -340,6 +341,9 @@ set_program_name__(const char *argv0, const char *version, const char *date,
const char *time)
{
const char *slash = strrchr(argv0, '/');
+
+ assert_single_threaded();
+
program_name = slash ? slash + 1 : argv0;
free(program_version);
--
1.7.2.5
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