From 91ff9e51605ecd7c64bbee47c79de889569e3d5f Mon Sep 17 00:00:00 2001
From: ratchet freak <ratchet.freak@gmail.com>
Date: Tue, 16 Jun 2026 20:35:39 +0200
Subject: [PATCH] fix crash when wait_barrier_slow is called with a nil barrier

other backends will guard against that before calling underlying api.
---
 src/base/base_threads.c | 82 +++++++++++++++++++++--------------------
 1 file changed, 42 insertions(+), 40 deletions(-)

diff --git a/src/base/base_threads.c b/src/base/base_threads.c
index a8c72585c..6c3c7a818 100644
--- a/src/base/base_threads.c
+++ b/src/base/base_threads.c
@@ -131,64 +131,66 @@ slow_barrier_wait(Barrier barrier)
 {
   ProfBeginFunction();
   BarrierNode *n = (BarrierNode *)barrier.u64[0];
-  U64 threads_left_to_enter = ins_atomic_u64_dec_eval(&n->threads_left_to_enter);
-  
-  //- rjf: threads left to enter > 0 => wait
-  if(threads_left_to_enter > 0)
+  if(n != 0) 
   {
-    // rjf: first try a spin loop
-    B32 done_waiting = 0;
-    ProfScope("spin loop wait") for(U64 spin_count = 0; spin_count < 10000; spin_count += 1)
-    {
-      if(ins_atomic_u64_eval(&n->threads_left_to_leave) != 0)
-      {
-        done_waiting = 1;
-        break;
-      }
-    }
+    U64 threads_left_to_enter = ins_atomic_u64_dec_eval(&n->threads_left_to_enter);
     
-    // rjf: not done waiting -> need to do slow wait on condition variable
-    if(!done_waiting) ProfScope("slow wait")
+    //- rjf: threads left to enter > 0 => wait
+    if(threads_left_to_enter > 0)
     {
-      RWMutexScope(n->rw_mutex, 0) for(;;)
+      // rjf: first try a spin loop
+      B32 done_waiting = 0;
+      ProfScope("spin loop wait") for(U64 spin_count = 0; spin_count < 10000; spin_count += 1)
       {
         if(ins_atomic_u64_eval(&n->threads_left_to_leave) != 0)
         {
+          done_waiting = 1;
           break;
         }
-        cond_var_wait_rw(n->cv, n->rw_mutex, 0, max_U64);
+      }
+      
+      // rjf: not done waiting -> need to do slow wait on condition variable
+      if(!done_waiting) ProfScope("slow wait")
+      {
+        RWMutexScope(n->rw_mutex, 0) for(;;)
+        {
+          if(ins_atomic_u64_eval(&n->threads_left_to_leave) != 0)
+          {
+            break;
+          }
+          cond_var_wait_rw(n->cv, n->rw_mutex, 0, max_U64);
+        }
+      }
+      
+      // rjf: decrement leave counter
+      if(ins_atomic_u64_dec_eval(&n->threads_left_to_leave) > 0)
+      {
+        ProfScope("signal") cond_var_signal(n->cv);
       }
     }
     
-    // rjf: decrement leave counter
-    if(ins_atomic_u64_dec_eval(&n->threads_left_to_leave) > 0)
+    //- rjf: threads left to enter == 0 -> last thread, wakeup
+    else
     {
+      ins_atomic_u64_eval_assign(&n->threads_left_to_enter, n->count);
+      ProfScope("wake up") RWMutexScope(n->rw_mutex, 1)
+      {
+        ins_atomic_u64_eval_assign(&n->threads_left_to_leave, n->count-1);
+      }
       ProfScope("signal") cond_var_signal(n->cv);
     }
-  }
-  
-  //- rjf: threads left to enter == 0 -> last thread, wakeup
-  else
-  {
-    ins_atomic_u64_eval_assign(&n->threads_left_to_enter, n->count);
-    ProfScope("wake up") RWMutexScope(n->rw_mutex, 1)
-    {
-      ins_atomic_u64_eval_assign(&n->threads_left_to_leave, n->count-1);
-    }
-    ProfScope("signal") cond_var_signal(n->cv);
-  }
-  
-  //- rjf: wait for threads left to leave == 0
-  ProfScope("wait for threads to leave") 
-  {
-    for(U64 spin_count = 0;; spin_count += 1)
+    
+    //- rjf: wait for threads left to leave == 0
+    ProfScope("wait for threads to leave") 
     {
-      if(ins_atomic_u64_eval(&n->threads_left_to_leave) == 0)
+      for(U64 spin_count = 0;; spin_count += 1)
       {
-        break;
+        if(ins_atomic_u64_eval(&n->threads_left_to_leave) == 0)
+        {
+          break;
+        }
       }
     }
   }
-  
   ProfEnd();
 }