linux-kernel - [PATCH v1 3/8] perf daemon: Use sig_atomic

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Message-Id: <20221024173523.602064-4-irogers@google.com>
Date:   Mon, 24 Oct 2022 10:35:18 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Leo Yan <leo.yan@...aro.org>,
        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>,
        Adrian Hunter <adrian.hunter@...el.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
Cc:     Stephane Eranian <eranian@...gle.com>,
        Ian Rogers <irogers@...gle.com>
Subject: [PATCH v1 3/8] perf daemon: Use sig_atomic_t to avoid UB

Use sig_atomic_t for a variable written to in a signal handler and
read elsewhere. This is undefined behavior as per:
https://wiki.sei.cmu.edu/confluence/display/c/SIG31-C.+Do+not+access+shared+objects+in+signal+handlers

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/builtin-daemon.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-daemon.c b/tools/perf/builtin-daemon.c
index 6cb3f6cc36d0..d05084952c09 100644
--- a/tools/perf/builtin-daemon.c
+++ b/tools/perf/builtin-daemon.c
@@ -9,6 +9,7 @@
 #include <string.h>
 #include <sys/file.h>
 #include <signal.h>
+#include <stdatomic.h>
 #include <stdlib.h>
 #include <time.h>
 #include <stdio.h>
@@ -105,7 +106,7 @@ static const char * const daemon_usage[] = {
 	NULL
 };
 
-static bool done;
+static volatile sig_atomic_t done;
 
 static void sig_handler(int sig __maybe_unused)
 {
-- 
2.38.0.135.g90850a2211-goog