linux-kernel - Re: [PATCH v1] perf test: Replace grep perl regexp with awk

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Message-ID: <aFrmtGhq2Di0OrD_@google.com>
Date: Tue, 24 Jun 2025 10:56:04 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: James Clark <james.clark@...aro.org>
Cc: Chun-Tse Shao <ctshao@...gle.com>, wy.shih90@...il.com,
	Ian Rogers <irogers@...gle.com>, peterz@...radead.org,
	mingo@...hat.com, acme@...nel.org, mark.rutland@....com,
	alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
	adrian.hunter@...el.com, kan.liang@...ux.intel.com,
	tmricht@...ux.ibm.com, leo.yan@....com, atrajeev@...ux.vnet.ibm.com,
	linux-perf-users@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] perf test: Replace grep perl regexp with awk

Hello,

On Mon, Jun 23, 2025 at 03:12:00PM +0100, James Clark wrote:
> 
> 
> On 20/06/2025 6:40 pm, Chun-Tse Shao wrote:
> > perl is not universal on all machines and should be replaced with awk,
> > which is much more common.
> > 
> > Before:
> >    $ perf test "probe libc's inet_pton & backtrace it with ping" -v
> >    --- start ---
> >    test child forked, pid 145431
> >    grep: Perl matching not supported in a --disable-perl-regexp build
> > 
> >    FAIL: could not add event
> >    ---- end(-1) ----
> >    121: probe libc's inet_pton & backtrace it with ping                 : FAILED!
> > After:
> >    $ perf test "probe libc's inet_pton & backtrace it with ping" -v
> >    121: probe libc's inet_pton & backtrace it with ping                 : Ok
> > 
> > Suggested-by: Ian Rogers <irogers@...gle.com>
> > Signed-off-by: Chun-Tse Shao <ctshao@...gle.com>
> > ---
> >   tools/perf/tests/shell/record+probe_libc_inet_pton.sh | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/tools/perf/tests/shell/record+probe_libc_inet_pton.sh b/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
> > index c4bab5b5cc59..aaa5ee06ae18 100755
> > --- a/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
> > +++ b/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
> > @@ -23,7 +23,8 @@ event_pattern='probe_libc:inet_pton(\_[[:digit:]]+)?'
> >   add_libc_inet_pton_event() {
> > 
> >   	event_name=$(perf probe -f -x $libc -a inet_pton 2>&1 | tail -n +2 | head -n -5 | \
> > -			grep -P -o "$event_pattern(?=[[:space:]]\(on inet_pton in $libc\))")
> > +			awk -v ep="$event_pattern" -v l="$libc" '$0 ~ ep && $0 ~ \
> > +			("\\(on inet_pton in " l "\\)") {print $1}')
> > 
> >   	if [ $? -ne 0 ] || [ -z "$event_name" ] ; then
> >   		printf "FAIL: could not add event\n"
> > --
> > 2.50.0.rc2.701.gf1e915cc24-goog
> > 
> 
> Minor nit: the underscore in event_pattern (not shown in the diff) never
> needed to be escaped.
> 
> But now we're using awk it gives a warning so we should remove it in case
> anyone is searching through the output:
> 
>   awk: warning: escape sequence `\_' treated as plain `_'
> 
> Reviewed-by: James Clark <james.clark@...aro.org>
 
Thanks for your review.  I'll fold the below change.

---8<---
diff --git a/tools/perf/tests/shell/record+probe_libc_inet_pton.sh b/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
index aaa5ee06ae1833de..9bdf47aabe9d738b 100755
--- a/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
+++ b/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
@@ -18,7 +18,7 @@
 libc=$(grep -w libc /proc/self/maps | head -1 | sed -r 's/.*[[:space:]](\/.*)/\1/g')
 nm -Dg $libc 2>/dev/null | grep -F -q inet_pton || exit 254
 
-event_pattern='probe_libc:inet_pton(\_[[:digit:]]+)?'
+event_pattern='probe_libc:inet_pton(_[[:digit:]]+)?'
 
 add_libc_inet_pton_event() {