fix deadlock error showing 'no span available' nonsense backtraces

Author: RalfJung

src/tools/miri/src/concurrency/thread.rs

@@ -515,10 +515,13 @@ impl<'tcx> ThreadManager<'tcx> {
         &mut self.threads[self.active_thread].stack
     }
 
-    pub fn all_stacks(
+    pub fn all_blocked_stacks(
         &self,
     ) -> impl Iterator<Item = (ThreadId, &[Frame<'tcx, Provenance, FrameExtra<'tcx>>])> {
-        self.threads.iter_enumerated().map(|(id, t)| (id, &t.stack[..]))
+        self.threads
+            .iter_enumerated()
+            .filter(|(_id, t)| matches!(t.state, ThreadState::Blocked { .. }))
+            .map(|(id, t)| (id, &t.stack[..]))
     }
 
     /// Create a new thread and returns its id.

src/tools/miri/src/diagnostics.rs

@@ -469,7 +469,7 @@ pub fn report_result<'tcx>(
     eprint!("{extra}"); // newlines are already in the string
 
     if show_all_threads {
-        for (thread, stack) in ecx.machine.threads.all_stacks() {
+        for (thread, stack) in ecx.machine.threads.all_blocked_stacks() {
             if thread != ecx.active_thread() {
                 let stacktrace = Frame::generate_stacktrace_from_stack(stack);
                 let (stacktrace, was_pruned) = prune_stacktrace(stacktrace, &ecx.machine);

src/tools/miri/tests/fail-dep/libc/eventfd_block_read_twice.rs

@@ -1,6 +1,4 @@
 //@only-target: linux android illumos
-//~^ERROR: deadlocked
-//~^^ERROR: deadlocked
 //@compile-flags: -Zmiri-deterministic-concurrency
 //@error-in-other-file: deadlock
 

src/tools/miri/tests/fail-dep/libc/eventfd_block_read_twice.stderr

@@ -14,24 +14,13 @@ note: inside `main`
 LL |     thread2.join().unwrap();
    |     ^^^^^^^^^^^^^^
 
-error: the evaluated program deadlocked
-   |
-   = note: this thread got stuck here
-   = note: (no span available)
-
 error: the evaluated program deadlocked
   --> tests/fail-dep/libc/eventfd_block_read_twice.rs:LL:CC
    |
 LL |         let res: i64 = unsafe { libc::read(fd, buf.as_mut_ptr().cast(), 8).try_into().unwrap() };
    |                                                                          ^ this thread got stuck here
 
-error: the evaluated program deadlocked
-   |
-   = note: this thread got stuck here
-   = note: (no span available)
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-error: aborting due to 4 previous errors
+error: aborting due to 2 previous errors
 

src/tools/miri/tests/fail-dep/libc/eventfd_block_write_twice.rs

@@ -1,6 +1,4 @@
 //@only-target: linux android illumos
-//~^ERROR: deadlocked
-//~^^ERROR: deadlocked
 //@compile-flags: -Zmiri-deterministic-concurrency
 //@error-in-other-file: deadlock
 
@@ -38,7 +36,7 @@ fn main() {
 
     let thread2 = thread::spawn(move || {
         let sized_8_data = (u64::MAX - 1).to_ne_bytes();
-        // Write u64::MAX - 1, so the all subsequent write will block.
+        // Write u64::MAX - 1, so that all subsequent writes will block.
         let res: i64 = unsafe {
             // This `write` will initially blocked, then get unblocked by thread3, then get blocked again
             // because the `write` in thread1 executes first.

src/tools/miri/tests/fail-dep/libc/eventfd_block_write_twice.stderr

@@ -14,24 +14,13 @@ note: inside `main`
 LL |     thread2.join().unwrap();
    |     ^^^^^^^^^^^^^^
 
-error: the evaluated program deadlocked
-   |
-   = note: this thread got stuck here
-   = note: (no span available)
-
 error: the evaluated program deadlocked
   --> tests/fail-dep/libc/eventfd_block_write_twice.rs:LL:CC
    |
 LL |             libc::write(fd, sized_8_data.as_ptr() as *const libc::c_void, 8).try_into().unwrap()
    |                                                                            ^ this thread got stuck here
 
-error: the evaluated program deadlocked
-   |
-   = note: this thread got stuck here
-   = note: (no span available)
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-error: aborting due to 4 previous errors
+error: aborting due to 2 previous errors
 

src/tools/miri/tests/fail-dep/libc/libc_epoll_block_two_thread.rs

@@ -1,11 +1,9 @@
 //@compile-flags: -Zmiri-deterministic-concurrency
-//~^ERROR: deadlocked
-//~^^ERROR: deadlocked
 //@only-target: linux android illumos
 //@error-in-other-file: deadlock
 
 use std::convert::TryInto;
-use std::thread::spawn;
+use std::thread;
 
 // Using `as` cast since `EPOLLET` wraps around
 const EPOLL_IN_OUT_ET: u32 = (libc::EPOLLIN | libc::EPOLLOUT | libc::EPOLLET) as _;
@@ -66,22 +64,21 @@ fn main() {
 
     let expected_event = u32::try_from(libc::EPOLLIN | libc::EPOLLOUT).unwrap();
     let expected_value = fds[0] as u64;
-    let thread1 = spawn(move || {
+    let thread1 = thread::spawn(move || {
         check_epoll_wait::<1>(epfd, &[(expected_event, expected_value)], -1);
-        //~^ERROR: deadlocked
     });
-    let thread2 = spawn(move || {
+    let thread2 = thread::spawn(move || {
         check_epoll_wait::<1>(epfd, &[(expected_event, expected_value)], -1);
+        //~^ERROR: deadlocked
     });
+    // Yield so the threads are both blocked.
+    thread::yield_now();
 
-    let thread3 = spawn(move || {
-        // Just a single write, so we only wake up one of them.
-        let data = "abcde".as_bytes().as_ptr();
-        let res = unsafe { libc::write(fds[1], data as *const libc::c_void, 5) };
-        assert!(res > 0 && res <= 5);
-    });
+    // Just a single write, so we only wake up one of them.
+    let data = "abcde".as_bytes().as_ptr();
+    let res = unsafe { libc::write(fds[1], data as *const libc::c_void, 5) };
+    assert!(res > 0 && res <= 5);
 
     thread1.join().unwrap();
     thread2.join().unwrap();
-    thread3.join().unwrap();
 }

src/tools/miri/tests/fail-dep/libc/libc_epoll_block_two_thread.stderr

@@ -1,8 +1,3 @@
-error: the evaluated program deadlocked
-   |
-   = note: this thread got stuck here
-   = note: (no span available)
-
 error: the evaluated program deadlocked
   --> RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
    |
@@ -16,7 +11,7 @@ LL |         let ret = unsafe { libc::pthread_join(id, ptr::null_mut()) };
 note: inside `main`
   --> tests/fail-dep/libc/libc_epoll_block_two_thread.rs:LL:CC
    |
-LL |     thread1.join().unwrap();
+LL |     thread2.join().unwrap();
    |     ^^^^^^^^^^^^^^
 
 error: the evaluated program deadlocked
@@ -25,13 +20,7 @@ error: the evaluated program deadlocked
 LL |         check_epoll_wait::<TAG>(epfd, &[(expected_event, expected_value)], -1);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this thread got stuck here
 
-error: the evaluated program deadlocked
-   |
-   = note: this thread got stuck here
-   = note: (no span available)
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-error: aborting due to 4 previous errors
+error: aborting due to 2 previous errors
 

src/tools/miri/tests/fail-dep/libc/socketpair-close-while-blocked.rs

@@ -1,6 +1,5 @@
 //! This is a regression test for <https://github.com/rust-lang/miri/issues/3947>: we had some
 //! faulty logic around `release_clock` that led to this code not reporting a data race.
-//~^^ERROR: deadlock
 //@ignore-target: windows # no libc socketpair on Windows
 //@compile-flags: -Zmiri-deterministic-concurrency
 //@error-in-other-file: deadlock

src/tools/miri/tests/fail-dep/libc/socketpair-close-while-blocked.stderr

@@ -20,12 +20,7 @@ error: the evaluated program deadlocked
 LL |             libc::read(fds[1], buf.as_mut_ptr().cast(), buf.len() as libc::size_t)
    |                                                                                  ^ this thread got stuck here
 
-error: the evaluated program deadlocked
-   |
-   = note: this thread got stuck here
-   = note: (no span available)
-
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors