linux-kernel - [PATCH 1/2] perf archive: Fix filtering of empty build-ids

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Message-ID: <442bffc7-ac5c-0975-b876-a549efce2413@codeweavers.com>
Date:   Fri, 19 Feb 2021 11:09:32 -0500
From:   Nicholas Fraser <nfraser@...eweavers.com>
To:     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@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Nicholas Fraser <nfraser@...eweavers.com>,
        Ian Rogers <irogers@...gle.com>, linux-kernel@...r.kernel.org
Cc:     Ulrich Czekalla <uczekalla@...eweavers.com>,
        Huw Davies <huw@...eweavers.com>
Subject: [PATCH 1/2] perf archive: Fix filtering of empty build-ids

A non-existent build-id used to be treated as all-zero SHA-1 hash.
Build-ids are now variable width. A non-existent build-id is an empty
string and "perf buildid-list" pads this with spaces. This is true even
when using old perf.data files recorded from older versions of perf;
"perf buildid-list" never reports an all-zero hash anymore.

This fixes "perf-archive" to skip missing build-ids by skipping lines
that start with a padding space rather than with zeroes.

Signed-off-by: Nicholas Fraser <nfraser@...eweavers.com>
---
 tools/perf/perf-archive.sh | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/tools/perf/perf-archive.sh b/tools/perf/perf-archive.sh
index 0cfb3e2cefef..133f0eddbcc4 100644
--- a/tools/perf/perf-archive.sh
+++ b/tools/perf/perf-archive.sh
@@ -20,9 +20,8 @@ else
 fi
 
 BUILDIDS=$(mktemp /tmp/perf-archive-buildids.XXXXXX)
-NOBUILDID=0000000000000000000000000000000000000000
 
-perf buildid-list -i $PERF_DATA --with-hits | grep -v "^$NOBUILDID " > $BUILDIDS
+perf buildid-list -i $PERF_DATA --with-hits | grep -v "^ " > $BUILDIDS
 if [ ! -s $BUILDIDS ] ; then
 	echo "perf archive: no build-ids found"
 	rm $BUILDIDS || true
-- 
2.30.1