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gh-117657: Fix TSan reported data race on ioctl_works (#120175)

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Sam Gross 2024-06-17 13:23:40 -04:00 • committed by GitHub
parent d9b4316374
commit 460cc9e14e
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2 changed files with 5 additions and 4 deletions
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8
Python/fileutils.c
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@ -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 */
}