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| 1 | +//@only-target: linux |
| 2 | +// test_epoll_race depends on a deterministic schedule. |
| 3 | +//@compile-flags: -Zmiri-preemption-rate=0 |
| 4 | + |
| 5 | +use std::convert::TryInto; |
| 6 | +use std::thread; |
| 7 | + |
| 8 | +fn main() { |
| 9 | + test_epoll_race(); |
| 10 | +} |
| 11 | + |
| 12 | +// Using `as` cast since `EPOLLET` wraps around |
| 13 | +const EPOLL_IN_OUT_ET: u32 = (libc::EPOLLIN | libc::EPOLLOUT | libc::EPOLLET) as _; |
| 14 | + |
| 15 | +#[track_caller] |
| 16 | +fn check_epoll_wait<const N: usize>( |
| 17 | + epfd: i32, |
| 18 | + expected_notifications: &[(u32, u64)], |
| 19 | + timeout: i32, |
| 20 | +) { |
| 21 | + let epoll_event = libc::epoll_event { events: 0, u64: 0 }; |
| 22 | + let mut array: [libc::epoll_event; N] = [epoll_event; N]; |
| 23 | + let maxsize = N; |
| 24 | + let array_ptr = array.as_mut_ptr(); |
| 25 | + let res = unsafe { libc::epoll_wait(epfd, array_ptr, maxsize.try_into().unwrap(), timeout) }; |
| 26 | + if res < 0 { |
| 27 | + panic!("epoll_wait failed: {}", std::io::Error::last_os_error()); |
| 28 | + } |
| 29 | + assert_eq!( |
| 30 | + res, |
| 31 | + expected_notifications.len().try_into().unwrap(), |
| 32 | + "got wrong number of notifications" |
| 33 | + ); |
| 34 | + let slice = unsafe { std::slice::from_raw_parts(array_ptr, res.try_into().unwrap()) }; |
| 35 | + for (return_event, expected_event) in slice.iter().zip(expected_notifications.iter()) { |
| 36 | + let event = return_event.events; |
| 37 | + let data = return_event.u64; |
| 38 | + assert_eq!(event, expected_event.0, "got wrong events"); |
| 39 | + assert_eq!(data, expected_event.1, "got wrong data"); |
| 40 | + } |
| 41 | +} |
| 42 | + |
| 43 | +// This test shows a data_race before epoll had vector clocks added. |
| 44 | +fn test_epoll_race() { |
| 45 | + // Create an epoll instance. |
| 46 | + let epfd = unsafe { libc::epoll_create1(0) }; |
| 47 | + assert_ne!(epfd, -1); |
| 48 | + |
| 49 | + // Create an eventfd instance. |
| 50 | + let flags = libc::EFD_NONBLOCK | libc::EFD_CLOEXEC; |
| 51 | + let fd = unsafe { libc::eventfd(0, flags) }; |
| 52 | + |
| 53 | + // Register eventfd with the epoll instance. |
| 54 | + let mut ev = libc::epoll_event { events: EPOLL_IN_OUT_ET, u64: fd as u64 }; |
| 55 | + let res = unsafe { libc::epoll_ctl(epfd, libc::EPOLL_CTL_ADD, fd, &mut ev) }; |
| 56 | + assert_eq!(res, 0); |
| 57 | + |
| 58 | + static mut VAL: u8 = 0; |
| 59 | + let thread1 = thread::spawn(move || { |
| 60 | + // Write to the static mut variable. |
| 61 | + unsafe { VAL = 1 }; |
| 62 | + // Write to the eventfd instance. |
| 63 | + let sized_8_data: [u8; 8] = 1_u64.to_ne_bytes(); |
| 64 | + let res = unsafe { libc::write(fd, sized_8_data.as_ptr() as *const libc::c_void, 8) }; |
| 65 | + // read returns number of bytes that have been read, which is always 8. |
| 66 | + assert_eq!(res, 8); |
| 67 | + }); |
| 68 | + thread::yield_now(); |
| 69 | + // epoll_wait for the event to happen. |
| 70 | + let expected_event = u32::try_from(libc::EPOLLIN | libc::EPOLLOUT).unwrap(); |
| 71 | + let expected_value = u64::try_from(fd).unwrap(); |
| 72 | + check_epoll_wait::<8>(epfd, &[(expected_event, expected_value)], -1); |
| 73 | + // Read from the static mut variable. |
| 74 | + #[allow(static_mut_refs)] |
| 75 | + unsafe { |
| 76 | + assert_eq!(VAL, 1) //~ ERROR: Data race detected |
| 77 | + }; |
| 78 | + thread1.join().unwrap(); |
| 79 | +} |
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