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

Ethan Jackson ethan at nicira.com
Wed Feb 23 23:54:15 UTC 2011


Looks Good.

On Wed, Feb 23, 2011 at 3:43 PM, Ben Pfaff <blp at nicira.com> wrote:
> 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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