[RFC PATCH glibc 26/34] hurd: Remove __hurd_local_reply_port

[Sergey Bugaev]

Now that the signal code no longer accesses it, the only real user of it
was mig-reply.c, so move the logic for managing the port there.

If we're in SHARED and outside of rtld, we know that __LIBC_NO_TLS ()
always evaluates to 0, and a TLS reply port will always be used, not
__hurd_reply_port0. Still, the compiler does not see that
__hurd_reply_port0 is never used due to its address being taken. To deal
with this, explicitly compile out __hurd_reply_port0 when we know we
won't use it.

Also, instead of accessing the port via THREAD_SELF->reply_port, this
uses THREAD_GETMEM and THREAD_SETMEM directly, avoiding possible
miscompilations.

Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
---
 hurd/hurd/threadvar.h         |  7 ------
 sysdeps/mach/hurd/mig-reply.c | 43 +++++++++++++++++++++++++++--------
 2 files changed, 33 insertions(+), 17 deletions(-)

diff --git a/hurd/hurd/threadvar.h b/hurd/hurd/threadvar.h
index f5c6a278..c476d988 100644
--- a/hurd/hurd/threadvar.h
+++ b/hurd/hurd/threadvar.h
@@ -29,11 +29,4 @@
 extern unsigned long int __hurd_sigthread_stack_base;
 extern unsigned long int __hurd_sigthread_stack_end;
 
-/* Store the MiG reply port reply port until we enable TLS.  */
-extern mach_port_t __hurd_reply_port0;
-
-/* This returns either the TLS reply port variable, or a single-thread variable
-   when TLS is not initialized yet.  */
-#define __hurd_local_reply_port (*(__LIBC_NO_TLS () ? &__hurd_reply_port0 : 
&THREAD_SELF->reply_port))
-
 #endif /* hurd/threadvar.h */
diff --git a/sysdeps/mach/hurd/mig-reply.c b/sysdeps/mach/hurd/mig-reply.c
index 33ff260e..d3c5a958 100644
--- a/sysdeps/mach/hurd/mig-reply.c
+++ b/sysdeps/mach/hurd/mig-reply.c
@@ -17,32 +17,55 @@
 
 #include <mach.h>
 #include <mach/mig_support.h>
-#include <hurd/threadvar.h>
+#include <tls.h>
 
 /* These functions are called by MiG-generated code.  */
 
+#if !defined (SHARED) || IS_IN (rtld)
 mach_port_t __hurd_reply_port0;
+#endif
+
+static mach_port_t
+get_reply_port (void)
+{
+#if !defined (SHARED) || IS_IN (rtld)
+  if (__LIBC_NO_TLS ())
+    return __hurd_reply_port0;
+#endif
+  return THREAD_GETMEM (THREAD_SELF, reply_port);
+}
+
+static void
+set_reply_port (mach_port_t port)
+{
+#if !defined (SHARED) || IS_IN (rtld)
+  if (__LIBC_NO_TLS ())
+    __hurd_reply_port0 = port;
+  else
+#endif
+    THREAD_SETMEM (THREAD_SELF, reply_port, port);
+}
 
 /* Called by MiG to get a reply port.  */
 mach_port_t
 __mig_get_reply_port (void)
 {
-  if (__hurd_local_reply_port == MACH_PORT_NULL
-      || (&__hurd_local_reply_port != &__hurd_reply_port0
-         && __hurd_local_reply_port == __hurd_reply_port0))
-    __hurd_local_reply_port = __mach_reply_port ();
-
-  return __hurd_local_reply_port;
+  mach_port_t port = get_reply_port ();
+  if (__glibc_unlikely (port == MACH_PORT_NULL))
+    {
+      port = __mach_reply_port ();
+      set_reply_port (port);
+    }
+  return port;
 }
 weak_alias (__mig_get_reply_port, mig_get_reply_port)
 libc_hidden_def (__mig_get_reply_port)
 
 /* Called by MiG to deallocate the reply port.  */
 void
-__mig_dealloc_reply_port (mach_port_t arg)
+__mig_dealloc_reply_port (mach_port_t port)
 {
-  mach_port_t port = __hurd_local_reply_port;
-  __hurd_local_reply_port = MACH_PORT_NULL;    /* So the mod_refs RPC won't 
use it.  */
+  set_reply_port (MACH_PORT_NULL);     /* So the mod_refs RPC won't use it.  */
 
   if (MACH_PORT_VALID (port))
     __mach_port_mod_refs (__mach_task_self (), port,
-- 
2.39.2