On Thu, 23 Aug 2018 13:25:34 +0300
Pavel Tikhomirov <ptikhomi...@virtuozzo.com> wrote:
> Then tracing syscall exit event it is extremely useful to filter exit
> codes equal to some negative value, to react only to required errors.
> But negative numbers does not work:
>
> [root@snorch sys_exit_read]# echo "ret == -1" > filter
> bash: echo: write error: Invalid argument
> [root@snorch sys_exit_read]# cat filter
> ret == -1
> ^
> parse_error: Invalid value (did you forget quotes)?
Thanks for the patch. I'll apply it and then start testing it!
-- Steve
>
> Similar thing happens when setting triggers.
>
> These is a regression in v4.17 introduced by the commit mentioned below,
> testing without these commit shows no problem with negative numbers.
>
> Fixes: 80765597bc58 ("tracing: Rewrite filter logic to be simpler and faster")
> Signed-off-by: Pavel Tikhomirov <ptikhomi...@virtuozzo.com>
> ---
> kernel/trace/trace_events_filter.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/trace/trace_events_filter.c
> b/kernel/trace/trace_events_filter.c
> index 84a65173b1e9..2ba449292561 100644
> --- a/kernel/trace/trace_events_filter.c
> +++ b/kernel/trace/trace_events_filter.c
> @@ -1299,7 +1299,7 @@ static int parse_pred(const char *str, void *data,
> /* go past the last quote */
> i++;
>
> - } else if (isdigit(str[i])) {
> + } else if (isdigit(str[i]) || str[i] == '-') {
>
> /* Make sure the field is not a string */
> if (is_string_field(field)) {
> @@ -1312,6 +1312,9 @@ static int parse_pred(const char *str, void *data,
> goto err_free;
> }
>
> + if (str[i] == '-')
> + i++;
> +
> /* We allow 0xDEADBEEF */
> while (isalnum(str[i]))
> i++;
