From 460cc9e14e221c53c0038a847bfd411fe184ebf3 Mon Sep 17 00:00:00 2001 From: Sam Gross Date: Mon, 17 Jun 2024 13:23:40 -0400 Subject: [PATCH] gh-117657: Fix TSan reported data race on ioctl_works (#120175) --- Python/fileutils.c | 8 +++++--- Tools/tsan/suppressions_free_threading.txt | 1 - 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/Python/fileutils.c b/Python/fileutils.c index e6a5391a3a2..c9ae1b3f54e 100644 --- a/Python/fileutils.c +++ b/Python/fileutils.c @@ -1502,7 +1502,7 @@ set_inheritable(int fd, int inheritable, int raise, int *atomic_flag_works) #else #if defined(HAVE_SYS_IOCTL_H) && defined(FIOCLEX) && defined(FIONCLEX) - if (ioctl_works != 0 && raise != 0) { + if (raise != 0 && _Py_atomic_load_int_relaxed(&ioctl_works) != 0) { /* fast-path: ioctl() only requires one syscall */ /* caveat: raise=0 is an indicator that we must be async-signal-safe * thus avoid using ioctl() so we skip the fast-path. */ @@ -1512,7 +1512,9 @@ set_inheritable(int fd, int inheritable, int raise, int *atomic_flag_works) request = FIOCLEX; err = ioctl(fd, request, NULL); if (!err) { - ioctl_works = 1; + if (_Py_atomic_load_int_relaxed(&ioctl_works) == -1) { + _Py_atomic_store_int_relaxed(&ioctl_works, 1); + } return 0; } @@ -1539,7 +1541,7 @@ set_inheritable(int fd, int inheritable, int raise, int *atomic_flag_works) with EACCES. While FIOCLEX is safe operation it may be unavailable because ioctl was denied altogether. This can be the case on Android. */ - ioctl_works = 0; + _Py_atomic_store_int_relaxed(&ioctl_works, 0); } /* fallback to fcntl() if ioctl() does not work */ } diff --git a/Tools/tsan/suppressions_free_threading.txt b/Tools/tsan/suppressions_free_threading.txt index 4c8b0b8abd2..b86c8fce11f 100644 --- a/Tools/tsan/suppressions_free_threading.txt +++ b/Tools/tsan/suppressions_free_threading.txt @@ -35,7 +35,6 @@ race_top:new_reference race_top:set_contains_key # https://gist.github.com/colesbury/d13d033f413b4ad07929d044bed86c35 race_top:set_discard_entry -race_top:set_inheritable race_top:_PyDict_CheckConsistency race_top:_Py_dict_lookup_threadsafe race_top:_multiprocessing_SemLock_acquire_impl