diff options
| -rw-r--r-- | src/tools/miri/src/shims/unix/linux_like/epoll.rs | 66 |
1 files changed, 27 insertions, 39 deletions
diff --git a/src/tools/miri/src/shims/unix/linux_like/epoll.rs b/src/tools/miri/src/shims/unix/linux_like/epoll.rs index c3f31ee0525..28b77f529c2 100644 --- a/src/tools/miri/src/shims/unix/linux_like/epoll.rs +++ b/src/tools/miri/src/shims/unix/linux_like/epoll.rs @@ -24,7 +24,13 @@ struct Epoll { // it. ready_list: Rc<ReadyList>, /// A list of thread ids blocked on this epoll instance. - thread_id: RefCell<Vec<ThreadId>>, + blocked_tid: RefCell<Vec<ThreadId>>, +} + +impl VisitProvenance for Epoll { + fn visit_provenance(&self, _visit: &mut VisitWith<'_>) { + // No provenance anywhere in this type. + } } /// EpollEventInstance contains information that will be returned by epoll_wait. @@ -362,7 +368,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> { // Notification will be returned for current epfd if there is event in the file // descriptor we registered. - check_and_update_one_event_interest(&fd_ref, interest, id, this)?; + check_and_update_one_event_interest(&fd_ref, &interest, id, this)?; interp_ok(Scalar::from_i32(0)) } else if op == epoll_ctl_del { let epoll_key = (id, fd); @@ -454,24 +460,15 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> { let Some(epfd) = this.machine.fds.get(epfd_value) else { return this.set_last_error_and_return(LibcError("EBADF"), dest); }; - let epoll_file_description = epfd - .downcast::<Epoll>() - .ok_or_else(|| err_unsup_format!("non-epoll FD passed to `epoll_wait`"))?; - // Create a weak ref of epfd and pass it to callback so we will make sure that epfd - // is not close after the thread unblocks. - let weak_epfd = FileDescriptionRef::downgrade(&epoll_file_description); + let Some(epfd) = epfd.downcast::<Epoll>() else { + return this.set_last_error_and_return(LibcError("EBADF"), dest); + }; // We just need to know if the ready list is empty and borrow the thread_ids out. - // The whole logic is wrapped inside a block so we don't need to manually drop epfd later. - let ready_list_empty; - let mut thread_ids; - { - ready_list_empty = epoll_file_description.ready_list.mapping.borrow().is_empty(); - thread_ids = epoll_file_description.thread_id.borrow_mut(); - } + let ready_list_empty = epfd.ready_list.mapping.borrow().is_empty(); if timeout == 0 || !ready_list_empty { // If the ready list is not empty, or the timeout is 0, we can return immediately. - return_ready_list(epfd_value, weak_epfd, dest, &event, this)?; + return_ready_list(&epfd, dest, &event, this)?; } else { // Blocking let timeout = match timeout { @@ -486,30 +483,30 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> { ); } }; - thread_ids.push(this.active_thread()); + // Record this thread as blocked. + epfd.blocked_tid.borrow_mut().push(this.active_thread()); + // And block it. let dest = dest.clone(); + // We keep a strong ref to the underlying `Epoll` to make sure it sticks around. + // This means there'll be a leak if we never wake up, but that anyway would imply + // a thread is permanently blocked so this is fine. this.block_thread( BlockReason::Epoll, timeout, callback!( @capture<'tcx> { - epfd_value: i32, - weak_epfd: WeakFileDescriptionRef<Epoll>, + epfd: FileDescriptionRef<Epoll>, dest: MPlaceTy<'tcx>, event: MPlaceTy<'tcx>, } @unblock = |this| { - return_ready_list(epfd_value, weak_epfd, &dest, &event, this)?; + return_ready_list(&epfd, &dest, &event, this)?; interp_ok(()) } @timeout = |this| { - // No notification after blocking timeout. - let Some(epfd) = weak_epfd.upgrade() else { - throw_unsup_format!("epoll FD {epfd_value} got closed while blocking.") - }; // Remove the current active thread_id from the blocked thread_id list. epfd - .thread_id.borrow_mut() + .blocked_tid.borrow_mut() .retain(|&id| id != this.active_thread()); this.write_int(0, &dest)?; interp_ok(()) @@ -538,12 +535,8 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> { if let Some(epoll_interests) = this.machine.epoll_interests.get_epoll_interest(id) { for weak_epoll_interest in epoll_interests { if let Some(epoll_interest) = weak_epoll_interest.upgrade() { - let is_updated = check_and_update_one_event_interest( - &fd_ref, - epoll_interest.clone(), - id, - this, - )?; + let is_updated = + check_and_update_one_event_interest(&fd_ref, &epoll_interest, id, this)?; if is_updated { // Edge-triggered notification only notify one thread even if there are // multiple threads blocked on the same epfd. @@ -554,7 +547,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> { // holds a strong ref to epoll_interest. let epfd = epoll_interest.borrow().weak_epfd.upgrade().unwrap(); // FIXME: We can randomly pick a thread to unblock. - if let Some(thread_id) = epfd.thread_id.borrow_mut().pop() { + if let Some(thread_id) = epfd.blocked_tid.borrow_mut().pop() { waiter.push(thread_id); }; } @@ -594,7 +587,7 @@ fn ready_list_next( /// notification to only one epoll instance. fn check_and_update_one_event_interest<'tcx>( fd_ref: &DynFileDescriptionRef, - interest: Rc<RefCell<EpollEventInterest>>, + interest: &Rc<RefCell<EpollEventInterest>>, id: FdId, ecx: &MiriInterpCx<'tcx>, ) -> InterpResult<'tcx, bool> { @@ -625,16 +618,11 @@ fn check_and_update_one_event_interest<'tcx>( /// Stores the ready list of the `epfd` epoll instance into `events` (which must be an array), /// and the number of returned events into `dest`. fn return_ready_list<'tcx>( - epfd_value: i32, - weak_epfd: WeakFileDescriptionRef<Epoll>, + epfd: &FileDescriptionRef<Epoll>, dest: &MPlaceTy<'tcx>, events: &MPlaceTy<'tcx>, ecx: &mut MiriInterpCx<'tcx>, ) -> InterpResult<'tcx> { - let Some(epfd) = weak_epfd.upgrade() else { - throw_unsup_format!("epoll FD {epfd_value} got closed while blocking.") - }; - let ready_list = epfd.get_ready_list(); let mut ready_list = ready_list.mapping.borrow_mut(); |