linux-kernel - Re: [PATCH v1] perf parse-events: Tidy name token matching

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Message-ID: <Z7ZD5phOOCbKggrn@google.com>
Date: Wed, 19 Feb 2025 12:49:42 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Andi Kleen <ak@...ux.intel.com>,
	Dominique Martinet <asmadeus@...ewreck.org>,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] perf parse-events: Tidy name token matching

Hi Ian,

On Wed, Feb 19, 2025 at 11:02:40AM -0800, Ian Rogers wrote:
> On Mon, Feb 10, 2025 at 11:23 AM Ian Rogers <irogers@...gle.com> wrote:
> >
> > On Thu, Jan 9, 2025 at 9:54 AM Ian Rogers <irogers@...gle.com> wrote:
> > >
> > > Prior to commit 70c90e4a6b2f ("perf parse-events: Avoid scanning PMUs
> > > before parsing") names (generally event names) excluded hyphen (minus)
> > > symbols as the formation of legacy names with hyphens was handled in
> > > the yacc code. That commit allowed hyphens supposedly making
> > > name_minus unnecessary. However, changing name_minus to name has
> > > issues in the term config tokens as then name ends up having priority
> > > over numbers and name allows matching numbers since commit
> > > 5ceb57990bf4 ("perf parse: Allow tracepoint names to start with digits
> > > "). It is also permissable for a name to match with a colon (':') in
> > > it when its in a config term list. To address this rename name_minus
> > > to term_name, make the pattern match name's except for the colon, add
> > > number matching into the config term region with a higher priority
> > > than name matching. This addresses an inconsistency and allows greater
> > > matching for names inside of term lists, for example, they may start
> > > with a number.
> > >
> > > Rename name_tag to quoted_name and update comments and helper
> > > functions to avoid str detecting quoted strings which was already done
> > > by the lexer.
> > >
> > > Signed-off-by: Ian Rogers <irogers@...gle.com>
> >
> > Ping. This patch addresses name parsing inconsistencies, in particular
> > events may start with a number without a PMU, but not with. It also
> > aims to give better names to patterns than name_minus and name_tag
> > (with term_name and quoted_name respectively) that have drifted from
> > their original meaning and become to me less than intention revealing.
> 
> Ping.

Sorry for the delay.  Can you please give an example for better
understanding if there's a change in the behavior?

Thanks,
Namhyung