The following call stack was possible:
vlog
-> worker_request()
-> poll_block()
-> vlog
-> worker_request()
which caused problems because worker_request() is not reentrant.
Bug #14616.
Signed-off-by: Ben Pfaff <b...@nicira.com>
---
lib/vlog.c | 30 +++++++++++++++++++++++-------
1 files changed, 23 insertions(+), 7 deletions(-)
diff --git a/lib/vlog.c b/lib/vlog.c
index 31ba96e..2587cde 100644
--- a/lib/vlog.c
+++ b/lib/vlog.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.
@@ -28,6 +28,7 @@
#include <syslog.h>
#include <time.h>
#include <unistd.h>
+#include "coverage.h"
#include "dirs.h"
#include "dynamic-string.h"
#include "ofpbuf.h"
@@ -40,6 +41,8 @@
VLOG_DEFINE_THIS_MODULE(vlog);
+COVERAGE_DEFINE(vlog_recursive);
+
/* Name for each logging level. */
static const char *level_names[VLL_N_LEVELS] = {
#define VLOG_LEVEL(NAME, SYSLOG_LEVEL) #NAME,
@@ -952,13 +955,26 @@ static void
vlog_write_file(struct ds *s)
{
if (worker_is_running()) {
- worker_request(s->string, s->length,
- &log_fd, vlog_async_inited ? 0 : 1,
- vlog_async_write_request_cb, NULL, NULL);
- vlog_async_inited = true;
- } else {
- ignore(write(log_fd, s->string, s->length));
+ static bool in_worker_request = false;
+ if (!in_worker_request) {
+ in_worker_request = true;
+
+ worker_request(s->string, s->length,
+ &log_fd, vlog_async_inited ? 0 : 1,
+ vlog_async_write_request_cb, NULL, NULL);
+ vlog_async_inited = true;
+
+ in_worker_request = false;
+ return;
+ } else {
+ /* We've been entered recursively. This can happen if
+ * worker_request(), or a function that it calls, tries to log
+ * something. We can't call worker_request() recursively, so fall
+ * back to writing the log file directly. */
+ COVERAGE_INC(vlog_recursive);
+ }
}
+ ignore(write(log_fd, s->string, s->length));
}
static void
--
1.7.2.5
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