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Use SYS_futex instead of __NR_futex 

Use the C library definition for portability; also test
for support instead of unconditionally enabling it.
This commit is contained in:
Robin Gareus 2022-05-30 21:56:49 +02:00
parent ce7d8ed8a1
commit 60db5a827f
Signed by: rgareus
GPG Key ID: A090BCE02CF57F04
2 changed files with 12 additions and 4 deletions
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4
libs/pbd/semutils.cc
View File

@ -105,7 +105,7 @@ int
Semaphore::signal ()
{
if (std::atomic_fetch_add_explicit (&_value, 1, std::memory_order_relaxed) < 0) {
while (syscall (__NR_futex, &_futex, FUTEX_WAKE_PRIVATE, 1, NULL, NULL, 0) < 1) {
while (syscall (SYS_futex, &_futex, FUTEX_WAKE_PRIVATE, 1, NULL, NULL, 0) < 1) {
sched_yield();
}
}
@ -116,7 +116,7 @@ int
Semaphore::wait ()
{
if (std::atomic_fetch_sub_explicit (&_value, 1, std::memory_order_relaxed) <= 0) {
syscall(__NR_futex, &_futex, FUTEX_WAIT_PRIVATE, _futex, NULL, 0, 0);
syscall(SYS_futex, &_futex, FUTEX_WAIT_PRIVATE, _futex, NULL, 0, 0);
}
return 0;
}

12
wscript
View File

@ -1358,8 +1358,16 @@ int main () { __int128 x = 0; return 0; }
conf.env['NO_THREADED_WAVEVIEWS'] = True
if not opts.no_futex_semaphore:
if re.search ("linux", sys.platform) is not None and Options.options.dist_target != 'mingw':
conf.define('USE_FUTEX_SEMAPHORE', 1)
conf.env['USE_FUTEX_SEMAPHORE'] = True
have_sys_futex = conf.check_cc(
msg="Checking for 'futex' syscall support",
features = 'c',
mandatory = False,
execute = False,
fragment = "#include <sys/syscall.h>\n#include <linux/futex.h>\nint main () { int x = SYS_futex | FUTEX_WAKE_PRIVATE; return 0; }")
if have_sys_futex:
conf.define('USE_FUTEX_SEMAPHORE', 1)
conf.env['USE_FUTEX_SEMAPHORE'] = True
backends = opts.with_backends.split(',')