relative futex and condvar timeouts can work with isolation

Author: RalfJung

src/tools/miri/src/shims/unix/linux/sync.rs

@@ -90,9 +90,11 @@ pub fn futex<'tcx>(
             let timeout_time = if this.ptr_is_null(timeout.ptr)? {
                 None
             } else {
-                this.check_no_isolation(
-                    "`futex` syscall with `op=FUTEX_WAIT` and non-null timeout",
-                )?;
+                if op & futex_realtime != 0 {
+                    this.check_no_isolation(
+                        "`futex` syscall with `op=FUTEX_WAIT` and non-null timeout with `FUTEX_CLOCK_REALTIME`",
+                    )?;
+                }
                 let duration = match this.read_timespec(&timeout)? {
                     Some(duration) => duration,
                     None => {

src/tools/miri/src/shims/unix/sync.rs

@@ -743,8 +743,6 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     ) -> InterpResult<'tcx> {
         let this = self.eval_context_mut();
 
-        this.check_no_isolation("`pthread_cond_timedwait`")?;
-
         let id = this.condvar_get_or_create_id(cond_op, CONDVAR_ID_OFFSET)?;
         let mutex_id = this.mutex_get_or_create_id(mutex_op, MUTEX_ID_OFFSET)?;
         let active_thread = this.get_active_thread();
@@ -761,6 +759,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
         };
 
         let timeout_time = if clock_id == this.eval_libc_i32("CLOCK_REALTIME")? {
+            this.check_no_isolation("`pthread_cond_timedwait` with `CLOCK_REALTIME`")?;
             Time::RealTime(SystemTime::UNIX_EPOCH.checked_add(duration).unwrap())
         } else if clock_id == this.eval_libc_i32("CLOCK_MONOTONIC")? {
             Time::Monotonic(this.machine.clock.anchor().checked_add(duration).unwrap())

src/tools/miri/src/shims/windows/sync.rs

@@ -254,8 +254,6 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
         let timeout_time = if timeout_ms == this.eval_windows("c", "INFINITE")?.to_u32()? {
             None
         } else {
-            this.check_no_isolation("`WaitOnAddress` with non-infinite timeout")?;
-
             let duration = Duration::from_millis(timeout_ms.into());
             Some(Time::Monotonic(this.machine.clock.now().checked_add(duration).unwrap()))
         };

src/tools/miri/tests/pass-dep/concurrency/libc_pthread_cond_isolated.rs

@@ -0,0 +1,82 @@
+//@ignore-target-windows: No libc on Windows
+//@ignore-target-apple: pthread_condattr_setclock is not supported on MacOS.
+
+/// Test that conditional variable timeouts are working properly
+/// with monotonic clocks even under isolation.
+use std::mem::MaybeUninit;
+use std::time::Instant;
+
+fn test_timed_wait_timeout(clock_id: i32) {
+    unsafe {
+        let mut attr: MaybeUninit<libc::pthread_condattr_t> = MaybeUninit::uninit();
+        assert_eq!(libc::pthread_condattr_init(attr.as_mut_ptr()), 0);
+        assert_eq!(libc::pthread_condattr_setclock(attr.as_mut_ptr(), clock_id), 0);
+
+        let mut cond: MaybeUninit<libc::pthread_cond_t> = MaybeUninit::uninit();
+        assert_eq!(libc::pthread_cond_init(cond.as_mut_ptr(), attr.as_ptr()), 0);
+        assert_eq!(libc::pthread_condattr_destroy(attr.as_mut_ptr()), 0);
+
+        let mut mutex: libc::pthread_mutex_t = libc::PTHREAD_MUTEX_INITIALIZER;
+
+        let mut now_mu: MaybeUninit<libc::timespec> = MaybeUninit::uninit();
+        assert_eq!(libc::clock_gettime(clock_id, now_mu.as_mut_ptr()), 0);
+        let now = now_mu.assume_init();
+        // Waiting for a second... mostly because waiting less requires mich more tricky arithmetic.
+        // FIXME: wait less.
+        let timeout = libc::timespec { tv_sec: now.tv_sec + 1, tv_nsec: now.tv_nsec };
+
+        assert_eq!(libc::pthread_mutex_lock(&mut mutex as *mut _), 0);
+        let current_time = Instant::now();
+        assert_eq!(
+            libc::pthread_cond_timedwait(cond.as_mut_ptr(), &mut mutex as *mut _, &timeout),
+            libc::ETIMEDOUT
+        );
+        let elapsed_time = current_time.elapsed().as_millis();
+        assert!(900 <= elapsed_time && elapsed_time <= 1300);
+
+        // Test calling `pthread_cond_timedwait` again with an already elapsed timeout.
+        assert_eq!(
+            libc::pthread_cond_timedwait(cond.as_mut_ptr(), &mut mutex as *mut _, &timeout),
+            libc::ETIMEDOUT
+        );
+
+        // Test that invalid nanosecond values (above 10^9 or negative) are rejected with the
+        // correct error code.
+        let invalid_timeout_1 = libc::timespec { tv_sec: now.tv_sec + 1, tv_nsec: 1_000_000_000 };
+        assert_eq!(
+            libc::pthread_cond_timedwait(
+                cond.as_mut_ptr(),
+                &mut mutex as *mut _,
+                &invalid_timeout_1
+            ),
+            libc::EINVAL
+        );
+        let invalid_timeout_2 = libc::timespec { tv_sec: now.tv_sec + 1, tv_nsec: -1 };
+        assert_eq!(
+            libc::pthread_cond_timedwait(
+                cond.as_mut_ptr(),
+                &mut mutex as *mut _,
+                &invalid_timeout_2
+            ),
+            libc::EINVAL
+        );
+        // Test that invalid second values (negative) are rejected with the correct error code.
+        let invalid_timeout_3 = libc::timespec { tv_sec: -1, tv_nsec: 0 };
+        assert_eq!(
+            libc::pthread_cond_timedwait(
+                cond.as_mut_ptr(),
+                &mut mutex as *mut _,
+                &invalid_timeout_3
+            ),
+            libc::EINVAL
+        );
+
+        assert_eq!(libc::pthread_mutex_unlock(&mut mutex as *mut _), 0);
+        assert_eq!(libc::pthread_mutex_destroy(&mut mutex as *mut _), 0);
+        assert_eq!(libc::pthread_cond_destroy(cond.as_mut_ptr()), 0);
+    }
+}
+
+fn main() {
+    test_timed_wait_timeout(libc::CLOCK_MONOTONIC);
+}

src/tools/miri/tests/pass/concurrency/thread_park_isolated.rs

@@ -0,0 +1,12 @@
+//@ignore-target-apple: park_timeout on macOS uses the system clock
+use std::thread;
+use std::time::{Duration, Instant};
+
+fn main() {
+    let start = Instant::now();
+
+    thread::park_timeout(Duration::from_millis(200));
+
+    // Thanks to deterministic execution, this will wiat *exactly* 200ms (rounded to 1ms).
+    assert!((200..201).contains(&start.elapsed().as_millis()));
+}