Messages in this thread | | | Date | Tue, 6 Feb 2018 11:26:14 +0900 | From | Masami Hiramatsu <> | Subject | Re: [RFC] apparent bogosity in unregister_ftrace_function_probe_func() |
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On Mon, 5 Feb 2018 17:54:33 -0500 Steven Rostedt <rostedt@goodmis.org> wrote:
> On Mon, 29 Jan 2018 22:59:42 +0900 > Masami Hiramatsu <mhiramat@kernel.org> wrote: > > > On Sat, 27 Jan 2018 17:07:48 +0000 > > Al Viro <viro@ZenIV.linux.org.uk> wrote: > > > > > On Sat, Jan 27, 2018 at 01:59:56PM +0000, Dmitry Safonov wrote: > > > > > > > > > Incidentally, shouldn't filter_parse_regex("*[ab]", 5, &s, ¬) > > > > > end up with s = "*[ab]"? We are returning MATCH_GLOB, after all, > > > > > so we want the entire pattern there... I would've assumed that > > > > > this is what the code in unregister_ftrace_function_probe_func() > > > > > is trying to compensate for, the first oddity predates MATCH_GLOB... > > > > > > > > No, I don't think filter_parse_regex() should return the full regex.. > > > > ftrace_match() expects search would be processed string, not a glob. > > > > So, this unnecessary assignment broke unregistering multiple kprobs > > > > with a middle/end pattern.. > > > > > > For substring - sure, but what about something like "*a*b" and "a*b"? > > > AFAICS, filter_parse_regex() ends up with identical results in both > > > cases - MATCH_GLOB and *search = "a*b". And no way for the caller > > > to tell one from another. > > > > > > IOW, it's a different bug sometimes obscured by the one in > > > unregister_ftrace_function_probe_func(). filter_parse_regex() > > > ought to revert to *search = buff; when it decides to return > > > MATCH_GLOB. Or something like > > > for (i = 0; i < len; i++) { > > > if (buff[i] == '*') { > > > if (!i) { > > > type = MATCH_END_ONLY; > > > } else if (i == len - 1) { > > > if (type == MATCH_END_ONLY) > > > type = MATCH_MIDDLE_ONLY; > > > else > > > type = MATCH_FRONT_ONLY; > > > buff[i] = 0; > > > break; > > > } else { /* pattern continues, use full glob */ > > > return MATCH_GLOB; > > > } > > > } else if (strchr("[?\\", buff[i])) { > > > return MATCH_GLOB; > > > } > > > } > > > if (buff[0] == '*') > > > *search = buff + 1; > > > for that matter - i.e. delay that "we want everything past the first character" > > > until we are certain it's not a MATCH_GLOB. > > > > Looks nice to me! > > > > I'll implement this code giving Al credit and referencing this email > thread. Anyone have objections to that?
No, that code looks good to me. :)
BTW, did you also remove "search = buff;" line in unregister_ftrace_function_probe_func() too?
Thanks!
-- Masami Hiramatsu <mhiramat@kernel.org>
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