fix: deregister I/O sources in blocking I/O manager

Author: WhySoBad

src/tools/miri/src/concurrency/blocking_io.rs

@@ -98,6 +98,9 @@ impl BlockingIoManager {
             })
             .collect::<Vec<_>>();
 
+        // Deregister all ready sources as we only want to receive one event per receiver.
+        ready.iter().for_each(|(receiver, source)| self.deregister(source.id(), *receiver));
+
         Ok(ready)
     }
 

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

@@ -823,12 +823,10 @@ trait EvalContextPrivExt<'tcx>: MiriInterpCxExt<'tcx> {
             Err(e) => panic!("unexpected error while polling: {e}"),
         };
 
-        ready.into_iter().try_for_each(|(receiver, source)| {
+        ready.into_iter().try_for_each(|(receiver, _source)| {
             match receiver {
-                InterestReceiver::UnblockThread(thread_id) => {
-                    this.machine.blocking_io.deregister(source.id(), receiver);
-                    this.unblock_thread(thread_id, BlockReason::IO)
-                }
+                InterestReceiver::UnblockThread(thread_id) =>
+                    this.unblock_thread(thread_id, BlockReason::IO),
             }
         })
     }