From 17157945bb417652840e94deba5bea4a2f1b3cb0 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Sat, 5 Feb 2011 16:33:02 -0700
Subject: [PATCH] fix scheduler's support for `ffi/unsafe/try-atomic'   where
 problems with abort-without-dynamic-wind mode caused   a spurious trigger of
 nack evts  Merge to 5.1 (cherry picked from commit
 3e38071dae88590befcb46ef953e123447af5e3f)

---
 src/racket/include/scheme.h |  5 ++++-
 src/racket/src/sema.c       |  3 ++-
 src/racket/src/thread.c     | 11 +++++++++++
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/racket/include/scheme.h b/src/racket/include/scheme.h
index 58e50d815d..60d500d28c 100644
--- a/src/racket/include/scheme.h
+++ b/src/racket/include/scheme.h
@@ -1155,7 +1155,10 @@ typedef void (*Scheme_Kill_Action_Func)(void *);
       thread = NULL; \
       if (scheme_setjmp(newbuf)) { \
         scheme_pop_kill_action(); \
-        func(data); \
+        thread = scheme_get_current_thread(); \
+        if (!thread->cjs.skip_dws) { \
+          func(data); \
+        } \
         scheme_longjmp(*savebuf, 1); \
       } else {
 # define END_ESCAPEABLE() \
diff --git a/src/racket/src/sema.c b/src/racket/src/sema.c
index 37cab3e519..0953a3117e 100644
--- a/src/racket/src/sema.c
+++ b/src/racket/src/sema.c
@@ -654,7 +654,8 @@ int scheme_wait_semas_chs(int n, Scheme_Object **o, int just_try, Syncing *synci
         } else if (semas[i]->so.type == scheme_never_evt_type) {
           /* Never ready. */
         } else if (semas[i]->so.type == scheme_channel_syncer_type) {
-          /* Probably no need to poll */
+          if (((Scheme_Channel_Syncer *)semas[i])->picked)
+            break;
         } else if (try_channel(semas[i], syncing, i, NULL))
           break;
       }
diff --git a/src/racket/src/thread.c b/src/racket/src/thread.c
index 85697facc9..988507af57 100644
--- a/src/racket/src/thread.c
+++ b/src/racket/src/thread.c
@@ -4051,6 +4051,9 @@ static void call_on_atomic_timeout(int must)
   Scheme_Object *blocker;
   Scheme_Ready_Fun block_check;
   Scheme_Needs_Wakeup_Fun block_needs_wakeup;
+  Scheme_Kill_Action_Func private_on_kill;
+  void *private_kill_data;
+  void **private_kill_next;
 
   /* Save any state that has to do with the thread blocking or 
      sleeping, in case scheme_on_atomic_timeout() runs Racket code. */
@@ -4062,6 +4065,10 @@ static void call_on_atomic_timeout(int must)
   block_check = p->block_check;
   block_needs_wakeup = p->block_needs_wakeup;
 
+  private_on_kill = p->private_on_kill;
+  private_kill_data = p->private_kill_data;
+  private_kill_next = p->private_kill_next;
+
   p->running = MZTHREAD_RUNNING;
   p->sleep_end = 0.0;
   p->block_descriptor = 0;
@@ -4077,6 +4084,10 @@ static void call_on_atomic_timeout(int must)
   p->blocker = blocker;
   p->block_check = block_check;
   p->block_needs_wakeup = block_needs_wakeup;
+
+  p->private_on_kill = private_on_kill;
+  p->private_kill_data = private_kill_data;
+  p->private_kill_next = private_kill_next;
 }
 
 static void find_next_thread(Scheme_Thread **return_arg) {