Check if the thread is blocked before waking them up

Author: tiif

src/concurrency/thread.rs

@@ -578,6 +578,10 @@ impl<'tcx> ThreadManager<'tcx> {
         self.threads[thread_id].state.is_terminated()
     }
 
+    fn has_blocked_on_epoll(&self, thread_id: ThreadId) -> bool {
+        self.threads[thread_id].state.is_blocked_on(BlockReason::Epoll)
+    }
+
     /// Have all threads terminated?
     fn have_all_terminated(&self) -> bool {
         self.threads.iter().all(|thread| thread.state.is_terminated())
@@ -1137,6 +1141,12 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         this.machine.threads.enable_thread(thread_id);
     }
 
+    #[inline]
+    fn has_blocked_on_epoll(&self, thread_id: ThreadId) -> bool {
+        let this = self.eval_context_ref();
+        this.machine.threads.has_blocked_on_epoll(thread_id)
+    }
+
     #[inline]
     fn active_thread_stack<'a>(&'a self) -> &'a [Frame<'tcx, Provenance, FrameExtra<'tcx>>] {
         let this = self.eval_context_ref();

src/shims/unix/linux/epoll.rs

@@ -600,7 +600,9 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         waiter.sort();
         waiter.dedup();
         for thread_id in waiter {
-            this.unblock_thread(thread_id, BlockReason::Epoll)?;
+            if this.has_blocked_on_epoll(thread_id) {
+                this.unblock_thread(thread_id, BlockReason::Epoll)?;
+            }
         }
         Ok(())
     }