From 78a817d84402583e7f492fd1ad0e785829ad53fb Mon Sep 17 00:00:00 2001
From: Valentin Churavy <v.churavy@gmail.com>
Date: Sat, 9 Sep 2023 18:13:49 -0400
Subject: [PATCH] Handle gcanalyzer

---
 src/jl_uv.c          | 13 ++++++++-----
 src/julia_internal.h |  4 ++--
 src/threading.c      | 16 +++++++++-------
 3 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/src/jl_uv.c b/src/jl_uv.c
index 5712a9fedb3b6..8d5414a2c6890 100644
--- a/src/jl_uv.c
+++ b/src/jl_uv.c
@@ -56,7 +56,7 @@ static void jl_uv_cb_walk_print(uv_handle_t *h, void *arg)
         jl_safe_printf(" %s[%zd] %s@%p->%p\n", type, (size_t)fd, pad, (void*)h, (void*)h->data);
 }
 
-static void jl_uv_cb_wait_empty(uv_timer_t *t)
+static void jl_uv_cb_wait_empty(uv_timer_t *t) JL_NOTSAFEPOINT_ENTER
 {
     // make sure this is hidden now, since we would auto-unref it later
     uv_unref((uv_handle_t*)&signal_async);
@@ -69,7 +69,7 @@ static void jl_uv_cb_wait_empty(uv_timer_t *t)
     jl_ptls_t ptls = jl_current_task->ptls;
     int old_state = jl_gc_unsafe_enter(ptls);
     jl_gc_collect(JL_GC_FULL);
-    jl_gc_unsafe_leave(ptls,old_state);
+    jl_gc_unsafe_leave(ptls, old_state);
 }
 
 void jl_wait_empty_begin(void)
@@ -154,7 +154,7 @@ JL_DLLEXPORT void jl_iolock_end(void)
 }
 
 
-static void jl_uv_call_hook_close(jl_value_t *val)
+static void jl_uv_call_hook_close(jl_value_t *val) JL_NOTSAFEPOINT_ENTER
 {
     jl_ptls_t ptls = jl_current_task->ptls;
     int old_state = jl_gc_unsafe_enter(ptls);
@@ -166,7 +166,7 @@ static void jl_uv_call_hook_close(jl_value_t *val)
     assert(args[0]);
     jl_apply(args, 2); // TODO: wrap in try-catch?
     JL_GC_POP();
-    jl_gc_unsafe_leave(ptls,old_state);
+    jl_gc_unsafe_leave(ptls, old_state);
 }
 
 static void jl_uv_cb_close_handle(uv_handle_t *handle)
@@ -282,7 +282,10 @@ JL_DLLEXPORT void *jl_uv_handle_data(uv_handle_t *handle) { return handle->data;
 JL_DLLEXPORT void *jl_uv_write_handle(uv_write_t *req) { return req->handle; }
 
 
-int jl_process_events_locked(void) {
+// This is JL_NOTSAFEPOINT, but the analyzer complains about uv_run.
+// Callabacks need to handle their GC transitions themselves.
+int jl_process_events_locked(void) // JL_NOTSAFEPOINT
+{
     uv_loop_t *loop = jl_io_loop;
     loop->stop_flag = 0;
     uv_ref((uv_handle_t*)&signal_async); // force the loop alive
diff --git a/src/julia_internal.h b/src/julia_internal.h
index 0f6ad5d01b097..a47d55e234cf7 100644
--- a/src/julia_internal.h
+++ b/src/julia_internal.h
@@ -181,8 +181,8 @@ static uv_loop_t *const unused_uv_loop_arg = (uv_loop_t *)0xBAD10;
 extern jl_mutex_t jl_uv_mutex;
 extern _Atomic(int) jl_uv_n_waiters;
 void JL_UV_LOCK(void);
-int JL_UV_TRYLOCK_NOGC(void);
-void JL_UV_UNLOCK_NOGC(void);
+int JL_UV_TRYLOCK_NOGC(void) JL_NOTSAFEPOINT;
+void JL_UV_UNLOCK_NOGC(void) JL_NOTSAFEPOINT;
 #define JL_UV_UNLOCK() JL_UNLOCK(&jl_uv_mutex)
 
 #ifdef __cplusplus
diff --git a/src/threading.c b/src/threading.c
index 1239696bdac6a..12df923e790a8 100644
--- a/src/threading.c
+++ b/src/threading.c
@@ -702,21 +702,22 @@ void jl_init_threading(void)
     gc_first_tid = nthreads;
 }
 
-int jl_process_events_locked(void);
-void jl_utility_io_threadfun(void *arg) {
-
+int jl_process_events_locked(void) JL_NOTSAFEPOINT;
+void jl_utility_io_threadfun(void *arg)
+{
     jl_adopt_thread();
     jl_ptls_t ptls = jl_current_task->ptls;
-    jl_gc_safe_enter(ptls);
+    int8_t gc_state  = jl_gc_safe_enter(ptls);
     while (1) {
-        // Only reader of the rwlock, according to libuv lock is writer-biased
         if (jl_atomic_load_relaxed(&jl_uv_n_waiters) == 0)
             if (JL_UV_TRYLOCK_NOGC())
             {
                 jl_process_events_locked();
                 JL_UV_UNLOCK_NOGC();
             }
+        // TODO: jl_fence(); // [^store_buffering_2]
     }
+    jl_gc_safe_leave(ptls, gc_state);
     return;
 }
 
@@ -781,10 +782,11 @@ void jl_start_threads(void)
         }
         uv_thread_detach(&uvtid);
     }
+    uv_barrier_wait(&thread_init_done);
+
+    // utility thread uses jl_adopt_thread
     uv_thread_create(&uvtid, jl_utility_io_threadfun, NULL);
     uv_thread_detach(&uvtid);
-
-    uv_barrier_wait(&thread_init_done);
 }
 
 // Profiling stubs