normal	2018-08-28 03:37:04 +0900 (Tue, 28 Aug 2018)

  New Revision: 64577

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=64577

  Log:
    process.c: fix potential missed wakeups in r64576
    
    Oddly, all existing test cases passed multiple times
    before this patch (even with --jit-wait), so this seems
    like a difficult failure to prove.
    
    Fixes: r64576 ("process.c: simplify SIGCHLD-based waitpid")

  Modified files:
    trunk/process.c
Index: process.c
===================================================================
--- process.c	(revision 64576)
+++ process.c	(revision 64577)
@@ -936,21 +936,19 @@ void rb_sigwait_fd_put(const rb_thread_t https://github.com/ruby/ruby/blob/trunk/process.c#L936
 void rb_thread_sleep_interruptible(void);
 
 static int
-sigwait_fd_migrate_signaled_p(struct waitpid_state *w)
+waitpid_signal(struct waitpid_state *w)
 {
-    int signaled = FALSE;
-    rb_thread_t *th = w->ec ? rb_ec_thread_ptr(w->ec) : 0;
-
-    if (th) rb_native_mutex_lock(&th->interrupt_lock);
-
-    if (w->cond) {
-        rb_native_cond_signal(w->cond);
-        signaled = TRUE;
+    if (w->ec) { /* rb_waitpid */
+        rb_threadptr_interrupt(rb_ec_thread_ptr(w->ec));
+        return TRUE;
     }
-
-    if (th) rb_native_mutex_unlock(&th->interrupt_lock);
-
-    return signaled;
+    else { /* ruby_waitpid_locked */
+        if (w->cond) {
+            rb_native_cond_signal(w->cond);
+            return TRUE;
+        }
+    }
+    return FALSE;
 }
 
 /*
@@ -964,10 +962,10 @@ sigwait_fd_migrate_sleeper(rb_vm_t *vm) https://github.com/ruby/ruby/blob/trunk/process.c#L962
     struct waitpid_state *w = 0;
 
     list_for_each(&vm->waiting_pids, w, wnode) {
-        if (sigwait_fd_migrate_signaled_p(w)) return;
+        if (waitpid_signal(w)) return;
     }
     list_for_each(&vm->waiting_grps, w, wnode) {
-        if (sigwait_fd_migrate_signaled_p(w)) return;
+        if (waitpid_signal(w)) return;
     }
 }
 
@@ -995,14 +993,7 @@ waitpid_each(struct list_head *head) https://github.com/ruby/ruby/blob/trunk/process.c#L993
 
         w->ret = ret;
         list_del_init(&w->wnode);
-        if (w->ec) { /* rb_waitpid */
-            rb_threadptr_interrupt(rb_ec_thread_ptr(w->ec));
-        }
-        else { /* ruby_waitpid_locked */
-            if (w->cond) {
-                rb_native_cond_signal(w->cond);
-            }
-        }
+        waitpid_signal(w);
     }
 }
 #else

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