# Re: \[PATCH v3 11/16\] tracing/filters: Check for trailing characters after newline in filter string

- From: Masami Hiramatsu (Google) \<mhiramat@kernel.org\>
- Date: 2026-10-29 00:03:52 
- List: linux-trace-kernel
- Page: https://ratatoskr.run/linux-trace-kernel/2026/10/17823820
- Thread: https://ratatoskr.run/linux-trace-kernel/2026/10/17814009/t.md

```text
On Wed, 28 Oct 2026 10:03:48 -0400, Steven Rostedt [ref] wrote:
> On Wed, 28 Oct 2026 10:28:10 +0900
> "Masami Hiramatsu (Google)" [ref] wrote:
> 
> > Hmm, IMHO, there is a bad implementation in __ftrace_set_clr_event_nolock().
> > It should make a working copy of the filter string and pass it to
> > apply_event_filter(). Or pass the filter string as `const char *`
> > so that it is copied in the apply_event_filter() side. The ownership
> > of the filter string is not clear here.
> 
> I noticed this when I applied the patch.
> 
> Yes, the correct solution is to pass in const char *filter to
> __ftrace_set_clr_event_nolock() (I was planning on doing this after the
> merge window closed). But no, making a copy in
> __ftrace_set_clr_event_nolock() is *not* the right solution. There's
> nothing in that function that modifies that string to suggest it needs to
> make a copy of it.
> 
> The correct solution is to pass const char *filter to apply_event_filter()
> and have *that* function do the copy. That was my plan to make a patch for.

OK, so at this moment I will follow Sashiko's suggestion.

Thanks!

> 
> -- Steve
> 
>

-- 
Masami Hiramatsu (Google) [ref]
```