Merge branch 'master' into i7050-reset-expected-read-write-record-counts

DynamoRIO · Oct 22, 2024 · b1feaeb · b1feaeb
2 parents 05ddb8a + a8ee909
commit b1feaeb
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Showing 2 changed files with 13 additions and 4 deletions.
diff --git a/clients/drcachesim/scheduler/scheduler.cpp b/clients/drcachesim/scheduler/scheduler.cpp
@@ -2946,7 +2946,8 @@ scheduler_tmpl_t<RecordType, ReaderType>::syscall_incurs_switch(input_info_t *in
 template <typename RecordType, typename ReaderType>
 typename scheduler_tmpl_t<RecordType, ReaderType>::stream_status_t
 scheduler_tmpl_t<RecordType, ReaderType>::set_cur_input(output_ordinal_t output,
-                                                        input_ordinal_t input)
+                                                        input_ordinal_t input,
+                                                        bool caller_holds_cur_input_lock)
 {
     // XXX i#5843: Merge tracking of current inputs with ready_queue.queue to better
     // manage the possible 3 states of each input (a live cur_input for an output stream,
@@ -2958,7 +2959,9 @@ scheduler_tmpl_t<RecordType, ReaderType>::set_cur_input(output_ordinal_t output,
     if (prev_input >= 0) {
         if (prev_input != input) {
             input_info_t &prev_info = inputs_[prev_input];
-            std::lock_guard<mutex_dbg_owned> lock(*prev_info.lock);
+            auto scoped_lock = caller_holds_cur_input_lock
+                ? std::unique_lock<mutex_dbg_owned>()
+                : std::unique_lock<mutex_dbg_owned>(*prev_info.lock);
             prev_info.cur_output = INVALID_OUTPUT_ORDINAL;
             prev_info.last_run_time = get_output_time(output);
             if (options_.schedule_record_ostream != nullptr) {
@@ -3146,7 +3149,10 @@ scheduler_tmpl_t<RecordType, ReaderType>::pick_next_input_as_previously(
                    output, index, segment.value.start_instruction);
             // Give up this input and go into a wait state.
             // We'll come back here on the next next_record() call.
-            set_cur_input(output, INVALID_INPUT_ORDINAL);
+            set_cur_input(output, INVALID_INPUT_ORDINAL,
+                          // Avoid livelock if prev input == cur input which happens
+                          // with back-to-back segments with the same input.
+                          index == outputs_[output].cur_input);
             outputs_[output].waiting = true;
             return sched_type_t::STATUS_WAIT;
         }

diff --git a/clients/drcachesim/scheduler/scheduler.h b/clients/drcachesim/scheduler/scheduler.h
@@ -1920,8 +1920,11 @@ template <typename RecordType, typename ReaderType> class scheduler_tmpl_t {
                              input_reader_info_t &reader_info);
 
     // The caller cannot hold the output or input lock.
+    // The caller can hold the output's current input's lock but must pass
+    // true for the 3rd parameter in that case.
     stream_status_t
-    set_cur_input(output_ordinal_t output, input_ordinal_t input);
+    set_cur_input(output_ordinal_t output, input_ordinal_t input,
+                  bool caller_holds_cur_input_lock = false);
 
     // Finds the next input stream for the 'output_ordinal'-th output stream.
     // No input_info_t lock can be held on entry.