@matheusbsbs / matheus-bagliano / commits / 6cdf8a7929

ThreadSanitizer: add suppressions

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> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Martin Ågren committed Aug 21, 2017 at 19:43 UTC 6cdf8a7929688ea5702ab53f450d038e973e64e1

3 files changed +24

.tsan-suppressions new

+10

@@ -0,0 +1,10 @@

1 +# Suppressions for ThreadSanitizer (tsan).

2 +#

3 +# This file is used by setting the environment variable TSAN_OPTIONS to, e.g.,

4 +# "suppressions=$(pwd)/.tsan-suppressions". Observe that relative paths such as

5 +# ".tsan-suppressions" might not work.

6 +

7 +# A static variable is written to racily, but we always write the same value, so

8 +# in practice it (hopefully!) doesn't matter.

9 +race:^want_color$

10 +race:^transfer_debug$

color.c

@@ -338,6 +338,13 @@ static int check_auto_color(void)

338

339 int want_color(int var)

340 {

341 + /*

342 + * NEEDSWORK: This function is sometimes used from multiple threads, and

343 + * we end up using want_auto racily. That "should not matter" since

344 + * we always write the same value, but it's still wrong. This function

345 + * is listed in .tsan-suppressions for the time being.

346 + */

347 +

348 static int want_auto = -1;

349

350 if (var < 0)

transport-helper.c

@@ -1117,6 +1117,13 @@ int transport_helper_init(struct transport *transport, const char *name)

1117 __attribute__((format (printf, 1, 2)))

1118 static void transfer_debug(const char *fmt, ...)

1119 {

1120 + /*

1121 + * NEEDSWORK: This function is sometimes used from multiple threads, and

1122 + * we end up using debug_enabled racily. That "should not matter" since

1123 + * we always write the same value, but it's still wrong. This function

1124 + * is listed in .tsan-suppressions for the time being.

1125 + */

1126 +

1127 va_list args;

1128 char msgbuf[PBUFFERSIZE];

1129 static int debug_enabled = -1;