From 7b7d1d6c4835d4e84517cc825aacb817d6435696 Mon Sep 17 00:00:00 2001
From: Mara Bos <m-ou.se@m-ou.se>
Date: Tue, 3 May 2022 09:08:38 +0200
Subject: [PATCH] Don't use futexes on netbsd.

The latest NetBSD release doesn't include the futex syscall yet.
---
 library/std/src/sys/unix/futex.rs             | 46 ++-----------------
 library/std/src/sys/unix/locks/mod.rs         |  1 -
 library/std/src/sys/unix/thread_parker.rs     |  1 -
 .../std/src/sys_common/thread_parker/mod.rs   |  1 -
 4 files changed, 5 insertions(+), 44 deletions(-)

diff --git a/library/std/src/sys/unix/futex.rs b/library/std/src/sys/unix/futex.rs
index fd046bdf19d..f91367da89c 100644
--- a/library/std/src/sys/unix/futex.rs
+++ b/library/std/src/sys/unix/futex.rs
@@ -4,27 +4,18 @@
     all(target_os = "emscripten", target_feature = "atomics"),
     target_os = "freebsd",
     target_os = "openbsd",
-    target_os = "netbsd",
     target_os = "dragonfly",
 ))]
 
 use crate::sync::atomic::AtomicU32;
 use crate::time::Duration;
 
-#[cfg(target_os = "netbsd")]
-pub const SYS___futex: i32 = 166;
-
 /// Wait for a futex_wake operation to wake us.
 ///
 /// Returns directly if the futex doesn't hold the expected value.
 ///
 /// Returns false on timeout, and true in all other cases.
-#[cfg(any(
-    target_os = "linux",
-    target_os = "android",
-    target_os = "freebsd",
-    target_os = "netbsd"
-))]
+#[cfg(any(target_os = "linux", target_os = "android", target_os = "freebsd"))]
 pub fn futex_wait(futex: &AtomicU32, expected: u32, timeout: Option<Duration>) -> bool {
     use super::time::Timespec;
     use crate::ptr::null;
@@ -65,19 +56,6 @@ pub fn futex_wait(futex: &AtomicU32, expected: u32, timeout: Option<Duration>) -
                         crate::ptr::invalid_mut(umtx_timeout_size),
                         umtx_timeout_ptr as *mut _,
                     )
-                } else if #[cfg(target_os = "netbsd")] {
-                    // Netbsd's futex syscall takes addr2 and val2 as separate arguments.
-                    // (Both are unused for FUTEX_WAIT[_BITSET].)
-                    libc::syscall(
-                        SYS___futex,
-                        futex as *const AtomicU32,
-                        libc::FUTEX_WAIT_BITSET | libc::FUTEX_PRIVATE_FLAG,
-                        expected,
-                        timespec.as_ref().map_or(null(), |t| &t.t as *const libc::timespec),
-                        null::<u32>(), // addr2: This argument is unused for FUTEX_WAIT_BITSET.
-                        0,             // val2: This argument is unused for FUTEX_WAIT_BITSET.
-                        !0u32,         // val3 / bitmask: A full bitmask, to make it behave like a regular FUTEX_WAIT.
-                    )
                 } else {
                     libc::syscall(
                         libc::SYS_futex,
@@ -106,34 +84,20 @@ pub fn futex_wait(futex: &AtomicU32, expected: u32, timeout: Option<Duration>) -
 /// or false if no thread was waiting on this futex.
 ///
 /// On some platforms, this always returns false.
-#[cfg(any(target_os = "linux", target_os = "android", target_os = "netbsd"))]
+#[cfg(any(target_os = "linux", target_os = "android"))]
 pub fn futex_wake(futex: &AtomicU32) -> bool {
     let ptr = futex as *const AtomicU32;
     let op = libc::FUTEX_WAKE | libc::FUTEX_PRIVATE_FLAG;
-    unsafe {
-        cfg_if::cfg_if! {
-            if #[cfg(target_os = "netbsd")] {
-                libc::syscall(SYS___futex, ptr, op, 1) > 0
-            } else {
-                libc::syscall(libc::SYS_futex, ptr, op, 1) > 0
-            }
-        }
-    }
+    unsafe { libc::syscall(libc::SYS_futex, ptr, op, 1) > 0 }
 }
 
 /// Wake up all threads that are waiting on futex_wait on this futex.
-#[cfg(any(target_os = "linux", target_os = "android", target_os = "netbsd"))]
+#[cfg(any(target_os = "linux", target_os = "android"))]
 pub fn futex_wake_all(futex: &AtomicU32) {
     let ptr = futex as *const AtomicU32;
     let op = libc::FUTEX_WAKE | libc::FUTEX_PRIVATE_FLAG;
     unsafe {
-        cfg_if::cfg_if! {
-            if #[cfg(target_os = "netbsd")] {
-                libc::syscall(SYS___futex, ptr, op, i32::MAX);
-            } else {
-                libc::syscall(libc::SYS_futex, ptr, op, i32::MAX);
-            }
-        }
+        libc::syscall(libc::SYS_futex, ptr, op, i32::MAX);
     }
 }
 
diff --git a/library/std/src/sys/unix/locks/mod.rs b/library/std/src/sys/unix/locks/mod.rs
index 27d007a1051..04c5c489fc9 100644
--- a/library/std/src/sys/unix/locks/mod.rs
+++ b/library/std/src/sys/unix/locks/mod.rs
@@ -5,7 +5,6 @@ cfg_if::cfg_if! {
         all(target_os = "emscripten", target_feature = "atomics"),
         target_os = "freebsd",
         target_os = "openbsd",
-        target_os = "netbsd",
         target_os = "dragonfly",
     ))] {
         mod futex;
diff --git a/library/std/src/sys/unix/thread_parker.rs b/library/std/src/sys/unix/thread_parker.rs
index 0da132337de..cf37c01598b 100644
--- a/library/std/src/sys/unix/thread_parker.rs
+++ b/library/std/src/sys/unix/thread_parker.rs
@@ -6,7 +6,6 @@
     all(target_os = "emscripten", target_feature = "atomics"),
     target_os = "freebsd",
     target_os = "openbsd",
-    target_os = "netbsd",
     target_os = "dragonfly",
 )))]
 
diff --git a/library/std/src/sys_common/thread_parker/mod.rs b/library/std/src/sys_common/thread_parker/mod.rs
index 5305f1f2dee..c789a388e05 100644
--- a/library/std/src/sys_common/thread_parker/mod.rs
+++ b/library/std/src/sys_common/thread_parker/mod.rs
@@ -5,7 +5,6 @@ cfg_if::cfg_if! {
         all(target_arch = "wasm32", target_feature = "atomics"),
         target_os = "freebsd",
         target_os = "openbsd",
-        target_os = "netbsd",
         target_os = "dragonfly",
     ))] {
         mod futex;