From: "Martin Ågren" <martin.agren@gmail.com>
To: unlisted-recipients:; (no To-header on input)
Cc: git@vger.kernel.org, Jeff King <peff@peff.net>
Subject: [PATCH v2 4/4] ThreadSanitizer: add suppressions
Date: Mon, 21 Aug 2017 19:43:48 +0200 [thread overview]
Message-ID: <09bbbcd1429a28774ea2d8c67ef6106ab558c296.1503323391.git.martin.agren@gmail.com> (raw)
In-Reply-To: <cover.1503323390.git.martin.agren@gmail.com>
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=$(pwd)/.tsan-suppressions". Observe
that relative paths such as ".tsan-suppressions" might not work.
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
---
v2: added NEEDSWORK; reworded the comments in the new file
color.c | 7 +++++++
transport-helper.c | 7 +++++++
.tsan-suppressions | 10 ++++++++++
3 files changed, 24 insertions(+)
create mode 100644 .tsan-suppressions
diff --git a/color.c b/color.c
index 7aa8b076f..9ccd954d6 100644
--- a/color.c
+++ b/color.c
@@ -338,6 +338,13 @@ static int check_auto_color(void)
int want_color(int var)
{
+ /*
+ * NEEDSWORK: This function is sometimes used from multiple threads, and
+ * we end up using want_auto racily. That "should not matter" since
+ * we always write the same value, but it's still wrong. This function
+ * is listed in .tsan-suppressions for the time being.
+ */
+
static int want_auto = -1;
if (var < 0)
diff --git a/transport-helper.c b/transport-helper.c
index 8f68d69a8..f50b34df2 100644
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -1117,6 +1117,13 @@ int transport_helper_init(struct transport *transport, const char *name)
__attribute__((format (printf, 1, 2)))
static void transfer_debug(const char *fmt, ...)
{
+ /*
+ * NEEDSWORK: This function is sometimes used from multiple threads, and
+ * we end up using debug_enabled racily. That "should not matter" since
+ * we always write the same value, but it's still wrong. This function
+ * is listed in .tsan-suppressions for the time being.
+ */
+
va_list args;
char msgbuf[PBUFFERSIZE];
static int debug_enabled = -1;
diff --git a/.tsan-suppressions b/.tsan-suppressions
new file mode 100644
index 000000000..8c85014a0
--- /dev/null
+++ b/.tsan-suppressions
@@ -0,0 +1,10 @@
+# Suppressions for ThreadSanitizer (tsan).
+#
+# This file is used by setting the environment variable TSAN_OPTIONS to, e.g.,
+# "suppressions=$(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$
--
2.14.1.151.gdfeca7a7e
next prev parent reply other threads:[~2017-08-21 17:44 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-15 12:53 [PATCH/RFC 0/5] Some ThreadSanitizer-results Martin Ågren
2017-08-15 12:53 ` [PATCH 1/5] convert: initialize attr_action in convert_attrs Martin Ågren
2017-08-15 14:17 ` Torsten Bögershausen
2017-08-15 14:29 ` Torsten Bögershausen
2017-08-15 14:40 ` Martin Ågren
2017-08-15 12:53 ` [PATCH 2/5] pack-objects: take lock before accessing `remaining` Martin Ågren
2017-08-15 19:50 ` Johannes Sixt
2017-08-15 12:53 ` [PATCH 3/5] Makefile: define GIT_THREAD_SANITIZER Martin Ågren
2017-08-15 12:53 ` [PATCH 4/5] strbuf_reset: don't write to slopbuf with ThreadSanitizer Martin Ågren
2017-08-15 18:43 ` Junio C Hamano
2017-08-15 19:06 ` Martin Ågren
2017-08-15 19:19 ` Junio C Hamano
2017-08-15 12:53 ` [PATCH 5/5] ThreadSanitizer: add suppressions Martin Ågren
2017-08-15 12:53 ` tsan: t3008: hashmap_add touches size from multiple threads Martin Ågren
2017-08-15 17:59 ` Jeff Hostetler
2017-08-15 18:17 ` Stefan Beller
2017-08-15 18:40 ` Martin Ågren
2017-08-15 18:48 ` Stefan Beller
2017-08-15 19:21 ` Martin Ågren
2017-08-15 20:46 ` Jeff Hostetler
2017-08-30 18:59 ` [PATCH] hashmap: address ThreadSanitizer concerns Jeff Hostetler
2017-08-30 18:59 ` [PATCH] hashmap: add API to disable item counting when threaded Jeff Hostetler
2017-09-01 23:31 ` Johannes Schindelin
2017-09-01 23:50 ` Jonathan Nieder
2017-09-05 16:39 ` Jeff Hostetler
2017-09-05 17:13 ` Martin Ågren
2017-09-02 8:17 ` Jeff King
2017-09-04 15:59 ` Johannes Schindelin
2017-09-05 16:54 ` Jeff Hostetler
2017-09-06 3:43 ` Junio C Hamano
2017-09-05 16:33 ` Jeff Hostetler
2017-09-02 8:05 ` Jeff King
2017-09-05 17:07 ` Jeff Hostetler
2017-09-02 8:39 ` Simon Ruderich
2017-09-06 1:24 ` Junio C Hamano
2017-09-06 15:33 ` Jeff Hostetler
2017-09-06 15:43 ` [PATCH v2] hashmap: address ThreadSanitizer concerns Jeff Hostetler
2017-09-06 15:43 ` [PATCH v2] hashmap: add API to disable item counting when threaded Jeff Hostetler
2017-08-15 12:53 ` tsan: t5400: set_try_to_free_routine Martin Ågren
2017-08-15 17:35 ` Stefan Beller
2017-08-15 18:44 ` Martin Ågren
2017-08-17 10:57 ` Jeff King
2017-08-20 10:06 ` [PATCH/RFC 0/5] Some ThreadSanitizer-results Jeff King
2017-08-20 10:45 ` Martin Ågren
2017-08-21 17:43 ` [PATCH v2 0/4] " Martin Ågren
2017-08-21 17:43 ` [PATCH v2 1/4] convert: always initialize attr_action in convert_attrs Martin Ågren
2017-08-21 17:43 ` [PATCH v2 2/4] pack-objects: take lock before accessing `remaining` Martin Ågren
2017-08-21 17:43 ` [PATCH v2 3/4] strbuf_setlen: don't write to strbuf_slopbuf Martin Ågren
2017-08-23 17:24 ` Junio C Hamano
2017-08-23 17:43 ` Martin Ågren
2017-08-23 18:30 ` Junio C Hamano
2017-08-23 20:37 ` Brandon Casey
2017-08-23 21:04 ` Junio C Hamano
2017-08-23 21:20 ` Brandon Casey
2017-08-23 21:54 ` Brandon Casey
2017-08-23 22:11 ` Brandon Casey
2017-08-24 16:52 ` Junio C Hamano
2017-08-24 18:29 ` Brandon Casey
2017-08-24 19:16 ` Martin Ågren
2017-08-23 22:24 ` Junio C Hamano
2017-08-23 22:39 ` Brandon Casey
2017-08-21 17:43 ` Martin Ågren [this message]
2017-08-25 17:04 ` [PATCH v2 4/4] ThreadSanitizer: add suppressions Jeff King
2017-08-28 20:56 ` [PATCH v2 0/4] Some ThreadSanitizer-results Jeff Hostetler
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