[ovs-dev] [PATCH] util: Make out_of_memory() call abort() instead of exit(EXIT_FAILURE).

Ben Pfaff blp at nicira.com
Wed Feb 23 23:43:56 UTC 2011


exit(EXIT_FAILURE) will make a monitoring process (the one created by
--monitor) think that it should exit.  But the most likely reason for
out_of_memory() to be called is a bug: probably, the process is trying
to allocate more memory than there is available address space, e.g.
something like malloc(-1).  So it's better, in my opinion, to call abort()
instead, so that the monitor process restarts the daemon and we are more
likely to stay alive and, in addition, get a core dump and a useful bug
report.

I decided to implement a new general-purpose function for this purpose in
case we run into other similar situations in the future.

(I haven't actually run into this problem in practice.  This commit is
just speculation about what is better behavior.)
---
 lib/util.c |   55 ++++++++++++++++++++++++++++++++++++++++++++++---------
 lib/util.h |    4 ++++
 2 files changed, 50 insertions(+), 9 deletions(-)

diff --git a/lib/util.c b/lib/util.c
index f784f03..b9dbdc4 100644
--- a/lib/util.c
+++ b/lib/util.c
@@ -34,7 +34,7 @@ const char *program_name;
 void
 out_of_memory(void)
 {
-    ovs_fatal(0, "virtual memory exhausted");
+    ovs_abort(0, "virtual memory exhausted");
 }
 
 void *
@@ -171,32 +171,69 @@ ovs_strzcpy(char *dst, const char *src, size_t size)
     }
 }
 
+/* Prints 'format' on stderr, formatting it like printf() does.  If 'err_no' is
+ * nonzero, then it is formatted with ovs_retval_to_string() and appended to
+ * the message inside parentheses.  Then, terminates with abort().
+ *
+ * This function is preferred to ovs_fatal() in a situation where it would make
+ * sense for a monitoring process to restart the daemon.
+ *
+ * 'format' should not end with a new-line, because this function will add one
+ * itself. */
+void
+ovs_abort(int err_no, const char *format, ...)
+{
+    va_list args;
+
+    va_start(args, format);
+    ovs_error_valist(err_no, format, args);
+    va_end(args);
+
+    abort();
+}
+
+/* Prints 'format' on stderr, formatting it like printf() does.  If 'err_no' is
+ * nonzero, then it is formatted with ovs_retval_to_string() and appended to
+ * the message inside parentheses.  Then, terminates with EXIT_FAILURE.
+ *
+ * 'format' should not end with a new-line, because this function will add one
+ * itself. */
 void
 ovs_fatal(int err_no, const char *format, ...)
 {
     va_list args;
 
-    fprintf(stderr, "%s: ", program_name);
     va_start(args, format);
-    vfprintf(stderr, format, args);
+    ovs_error_valist(err_no, format, args);
     va_end(args);
-    if (err_no != 0)
-        fprintf(stderr, " (%s)", ovs_retval_to_string(err_no));
-    putc('\n', stderr);
 
     exit(EXIT_FAILURE);
 }
 
+/* Prints 'format' on stderr, formatting it like printf() does.  If 'err_no' is
+ * nonzero, then it is formatted with ovs_retval_to_string() and appended to
+ * the message inside parentheses.
+ *
+ * 'format' should not end with a new-line, because this function will add one
+ * itself. */
 void
 ovs_error(int err_no, const char *format, ...)
 {
-    int save_errno = errno;
     va_list args;
 
-    fprintf(stderr, "%s: ", program_name);
     va_start(args, format);
-    vfprintf(stderr, format, args);
+    ovs_error_valist(err_no, format, args);
     va_end(args);
+}
+
+/* Same as ovs_error() except that the arguments are supplied as a va_list. */
+void
+ovs_error_valist(int err_no, const char *format, va_list args)
+{
+    int save_errno = errno;
+
+    fprintf(stderr, "%s: ", program_name);
+    vfprintf(stderr, format, args);
     if (err_no != 0) {
         fprintf(stderr, " (%s)", ovs_retval_to_string(err_no));
     }
diff --git a/lib/util.h b/lib/util.h
index e741067..635d331 100644
--- a/lib/util.h
+++ b/lib/util.h
@@ -135,9 +135,13 @@ void *x2nrealloc(void *p, size_t *n, size_t s);
 void ovs_strlcpy(char *dst, const char *src, size_t size);
 void ovs_strzcpy(char *dst, const char *src, size_t size);
 
+void ovs_abort(int err_no, const char *format, ...)
+    PRINTF_FORMAT(2, 3) NO_RETURN;
 void ovs_fatal(int err_no, const char *format, ...)
     PRINTF_FORMAT(2, 3) NO_RETURN;
 void ovs_error(int err_no, const char *format, ...) PRINTF_FORMAT(2, 3);
+void ovs_error_valist(int err_no, const char *format, va_list)
+    PRINTF_FORMAT(2, 0);
 const char *ovs_retval_to_string(int);
 void ovs_hex_dump(FILE *, const void *, size_t, uintptr_t offset, bool ascii);
 
-- 
1.7.2.3





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