Re: Fork issue with timerfd

[Corinna Vinschen <corinna-cygwin@cygwin.com>]

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On Feb 24 17:27, Ken Brown wrote:
> I'm seeing sporadic errors like this on 64-bit Cygwin when I first start emacs:
> 
>        0 [main] emacs-X11 864 C:\cygwin64\bin\emacs-X11.exe: *** fatal error in 
> forked process - Can't recreate shared timerfd section during fork!
>        0 [main] emacs 860 dofork: child 864 - died waiting for dll loading, errno 11
> 
> If I exit and restart, everything will be fine almost every time.

I think I see where the thinko was here.  Can you try this?

diff --git a/winsup/cygwin/timerfd.cc b/winsup/cygwin/timerfd.cc
index 7e6be72b225a..7eda71ddb235 100644
--- a/winsup/cygwin/timerfd.cc
+++ b/winsup/cygwin/timerfd.cc
@@ -408,6 +408,7 @@ void
 timerfd_tracker::fixup_after_fork_exec (bool execing)
 {
   NTSTATUS status;
+  PVOID base_address = NULL;
   OBJECT_ATTRIBUTES attr;
   SIZE_T vsize = PAGE_SIZE;
 
@@ -416,11 +417,12 @@ timerfd_tracker::fixup_after_fork_exec (bool execing)
     return;
   /* Recreate shared section mapping */
   status = NtMapViewOfSection (tfd_shared_hdl, NtCurrentProcess (),
-			       (void **) &tfd_shared, 0, PAGE_SIZE, NULL,
+			       &base_address, 0, PAGE_SIZE, NULL,
 			       &vsize, ViewShare, MEM_TOP_DOWN, PAGE_READWRITE);
   if (!NT_SUCCESS (status))
-    api_fatal ("Can't recreate shared timerfd section during %s!",
-	       execing ? "execve" : "fork");
+    api_fatal ("Can't recreate shared timerfd section during %s, status %y!",
+	       execing ? "execve" : "fork", status);
+  tfd_shared = (timerfd_shared *) base_address;
   /* Increment global instance count by the number of instances in this
      process */
   InterlockedAdd (&tfd_shared->instance_count, local_instance_count);


Thanks,
Corinna

-- 
Corinna Vinschen
Cygwin Maintainer

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