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[take 2] Re: (patch) makethread stdcall/cdecl confusion

Chris Faylor <> writes:
> Ah.  I see where you were coming from, then.  The synchronization is
> there specifically to work around this particular problem.
> I don't see any reason to avoid using the stack since the
> synchronization is there to ensure that it's ok for the first thread to
> return (guess how long it took me to realize that I needed this).  I'd
> assumed that it is considerably less expensive to copy a few elements
> from the stack than it is to malloc something.  Maybe this is moot if we
> can actually eliminate the CreateEvent/SetEvent/WaitForSingleObject but
> your patch doesn't do that.  It does potentially use up a block of
> memory in the heap which could be in use for a long period of time.
> Maybe what is really needed here are some comments...

My oversight. Trivially fixed by going back to structure copy and 
free'ing the passed in pointer right away. Patch below.

Frankly, I don't quite understand why the synchronization (which is
always more expensive not doing it ;-) is needed. The part that I
have not looked at in detail is what may happen in sig_send if the
signal thread hasn't gotten there quite yet. With the change below,
either way will be safe at least from the parameter lifetime issue.

Thu Sep 16 20:04:16 1999  Mumit Khan  <>

	* (stdlib.h): Unconditionally include. 
	(thread_stub): Deallocate passed parameter.
	(makethread): Don't pass stack data to thread start routine.

---	Thu Sep 16 12:14:44 1999
+++	Thu Sep 16 20:03:33 1999
@@ -9,6 +9,7 @@ details. */
 #include "winsup.h"
 #include "exceptions.h"
+#include <stdlib.h>
 #undef lock
 #undef unlock
@@ -86,6 +87,8 @@ thread_stub (VOID *arg)
   exception_list except_entry;
   thread_start info = *((thread_start *) arg);
+  free (arg);
   /* Needed for the reent's  of this local dll thread
      I assume that the local threads are using the reent structure of
      the main thread
@@ -109,11 +112,18 @@ makethread (DWORD (*start) (void *), LPV
   DWORD tid;
   HANDLE h;
-  thread_start info;
+  // This is deallocated by thread_stub.
+  thread_start *info = (thread_start *) malloc (sizeof (thread_start));
+  if (! info)
+    {
+      debug_printf ("malloc failed, %E");
+    }
-  info.func = start;
-  info.arg = param;
-  info.sync = CreateEvent (&sec_none_nih, FALSE, FALSE, NULL);
+  info->func = start;
+  info->arg = param;
+  info->sync = CreateEvent (&sec_none_nih, FALSE, FALSE, NULL);
   if (*name != '+')
     sa = &sec_none_nih;
@@ -123,12 +133,12 @@ makethread (DWORD (*start) (void *), LPV
       sa = &sec_none;
-  if ((h = CreateThread (sa, 0, thread_stub, (VOID *)&info, flags, &tid)))
+  if ((h = CreateThread (sa, 0, thread_stub, (VOID *)info, flags, &tid)))
       regthread (name, tid);
-      WaitForSingleObject (info.sync, INFINITE);
+      WaitForSingleObject (info->sync, INFINITE);
-  CloseHandle (info.sync);
+  CloseHandle (info->sync);
   return h;
@@ -164,7 +174,6 @@ threadname (DWORD tid, int lockit)
-#include <stdlib.h>
 typedef struct _h


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