linux-kernel - [PATCH v4 05/22] perf symbol: Sort names under write lock

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Message-Id: <20230320033810.980165-6-irogers@google.com>
Date:   Sun, 19 Mar 2023 20:37:53 -0700
From:   Ian Rogers <irogers@...gle.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@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Darren Hart <dvhart@...radead.org>,
        Davidlohr Bueso <dave@...olabs.net>,
        "André Almeida" <andrealmeid@...labora.com>,
        James Clark <james.clark@....com>,
        John Garry <john.g.garry@...cle.com>,
        Riccardo Mancini <rickyman7@...il.com>,
        Yury Norov <yury.norov@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Leo Yan <leo.yan@...aro.org>, Andi Kleen <ak@...ux.intel.com>,
        Thomas Richter <tmricht@...ux.ibm.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Madhavan Srinivasan <maddy@...ux.ibm.com>,
        Shunsuke Nakamura <nakamura.shun@...itsu.com>,
        Song Liu <song@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Miaoqian Lin <linmq006@...il.com>,
        Stephen Brennan <stephen.s.brennan@...cle.com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>,
        German Gomez <german.gomez@....com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        Eric Dumazet <edumazet@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>, Hao Luo <haoluo@...gle.com>
Cc:     Stephane Eranian <eranian@...gle.com>,
        Ian Rogers <irogers@...gle.com>
Subject: [PATCH v4 05/22] perf symbol: Sort names under write lock

If finding a name doesn't find the sorted names then they are
allocated and sorted. This shouldn't be done under a read lock as
another reader may access it. Release the read lock and acquire the
write lock, then release the write lock and reacquire the read lock.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/symbol.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 317c0706852f..a458aa8b87bb 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -2018,6 +2018,9 @@ static int map__groups__sort_by_name_from_rbtree(struct maps *maps)
 	if (maps_by_name == NULL)
 		return -1;
 
+	up_read(&maps->lock);
+	down_write(&maps->lock);
+
 	maps->maps_by_name = maps_by_name;
 	maps->nr_maps_allocated = maps->nr_maps;
 
@@ -2025,6 +2028,10 @@ static int map__groups__sort_by_name_from_rbtree(struct maps *maps)
 		maps_by_name[i++] = map;
 
 	__maps__sort_by_name(maps);
+
+	up_write(&maps->lock);
+	down_read(&maps->lock);
+
 	return 0;
 }
 
-- 
2.40.0.rc1.284.g88254d51c5-goog