Re: [RFC][PATCH 07/10] tracing: Have zero size length in filter logic be full string
From: Masami Hiramatsu
Date: Sat May 12 2018 - 08:40:42 EST
On Fri, 11 May 2018 15:49:34 -0400
Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>
> As strings in trace events may not have a nul terminating character, the
> filter string compares use the defined string length for the field for the
> The trace_marker records data slightly different than do normal events. It's
> size is zero, meaning that the string is the rest of the array, and that the
> string also ends with '\0'.
> If the size is zero, assume that the string is nul terminated and read the
> string in question as is.
> Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
> kernel/trace/trace_events_filter.c | 23 ++++++++++++-----------
> 1 file changed, 12 insertions(+), 11 deletions(-)
> diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
> index 7d306b74230f..675392b9edd2 100644
> --- a/kernel/trace/trace_events_filter.c
> +++ b/kernel/trace/trace_events_filter.c
> @@ -750,31 +750,32 @@ static int filter_pred_none(struct filter_pred *pred, void *event)
> * Note:
> * - @str might not be NULL-terminated if it's of type DYN_STRING
> - * or STATIC_STRING
> + * or STATIC_STRING, unless @len is zero.
> static int regex_match_full(char *str, struct regex *r, int len)
> - if (strncmp(str, r->pattern, len) == 0)
> - return 1;
> - return 0;
> + /* len means str is dynamic and ends with '\0' */
!len (or len == 0)?
Masami Hiramatsu <mhiramat@xxxxxxxxxx>