From e61e6ae5878fe2843a3dd7fe7f531552a3ac4497 Mon Sep 17 00:00:00 2001
From: normal <normal@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Mon, 27 Aug 2018 18:37:04 +0000
Subject: 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")

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64577 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 process.c | 37 ++++++++++++++-----------------------
 1 file changed, 14 insertions(+), 23 deletions(-)

(limited to 'process.c')

diff --git a/process.c b/process.c
index 86b196cfef..94060de148 100644
--- a/process.c
+++ b/process.c
@@ -936,21 +936,19 @@ void rb_sigwait_fd_put(const rb_thread_t *, int fd);
 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)
     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)
 
         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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