From 6cdf8a7929688ea5702ab53f450d038e973e64e1 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Martin=20=C3=85gren?= Date: Mon, 21 Aug 2017 19:43:48 +0200 Subject: [PATCH] ThreadSanitizer: add suppressions MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add a file .tsan-suppressions and list two functions in it: want_color() and transfer_debug(). Both of these use the pattern static int foo = -1; if (foo < 0) foo = bar(); where bar always returns the same non-negative value. This can cause ThreadSanitizer to diagnose a race when foo is written from two threads. That is indeed a race, although it arguably doesn't matter in practice since it's always the same value that is written. Add NEEDSWORK-comments to the functions so that this problem is not forever swept way under the carpet. The suppressions-file is used by setting the environment variable TSAN_OPTIONS to, e.g., "suppressions=$(pwd)/.tsan-suppressions". Observe that relative paths such as ".tsan-suppressions" might not work. Signed-off-by: Martin Ågren Signed-off-by: Junio C Hamano --- .tsan-suppressions | 10 ++++++++++ color.c | 7 +++++++ transport-helper.c | 7 +++++++ 3 files changed, 24 insertions(+) create mode 100644 .tsan-suppressions diff --git a/.tsan-suppressions b/.tsan-suppressions new file mode 100644 index 0000000000..8c85014a0a --- /dev/null +++ b/.tsan-suppressions @@ -0,0 +1,10 @@ +# Suppressions for ThreadSanitizer (tsan). +# +# This file is used by setting the environment variable TSAN_OPTIONS to, e.g., +# "suppressions=$(pwd)/.tsan-suppressions". Observe that relative paths such as +# ".tsan-suppressions" might not work. + +# A static variable is written to racily, but we always write the same value, so +# in practice it (hopefully!) doesn't matter. +race:^want_color$ +race:^transfer_debug$ diff --git a/color.c b/color.c index 31b6207a00..9a9261ac16 100644 --- a/color.c +++ b/color.c @@ -338,6 +338,13 @@ static int check_auto_color(void) int want_color(int var) { + /* + * NEEDSWORK: This function is sometimes used from multiple threads, and + * we end up using want_auto racily. That "should not matter" since + * we always write the same value, but it's still wrong. This function + * is listed in .tsan-suppressions for the time being. + */ + static int want_auto = -1; if (var < 0) diff --git a/transport-helper.c b/transport-helper.c index 33cff38cc0..2b830b2290 100644 --- a/transport-helper.c +++ b/transport-helper.c @@ -1117,6 +1117,13 @@ int transport_helper_init(struct transport *transport, const char *name) __attribute__((format (printf, 1, 2))) static void transfer_debug(const char *fmt, ...) { + /* + * NEEDSWORK: This function is sometimes used from multiple threads, and + * we end up using debug_enabled racily. That "should not matter" since + * we always write the same value, but it's still wrong. This function + * is listed in .tsan-suppressions for the time being. + */ + va_list args; char msgbuf[PBUFFERSIZE]; static int debug_enabled = -1;