Changes to the LINUX_THREADS support to only allocate extra memory for

shared signal handling when there is shared signal handling being
used.

This removes the main objection to making the shared signal handling
a standard ability in rfork() and friends and 'unconditionalising'
this code. (i.e. the allocation of an extra 328 bytes per process).

Signal handling information remains in the U area until such a time as
it's reference count would be incremented to > 1. At that point a new
struct is malloc'd and maintained in KVM so that it can be shared between
the processes (threads) using it.

A function to check the reference count and move the struct back to the U
area when it drops back to 1 is also supplied. Signal information is
therefore now swapable for all processes that are not sharing that
information with other processes. THis should addres the concerns raised
by Garrett and others.

Submitted by:	"Richard Seaman, Jr." <dick@tar.com>

1 files changed, 1 insertions, 11 deletions

diff --git a/sys/kern/init_main.c b/sys/kern/init_main.c
index 9269b26..246684f 100644
--- a/sys/kern/init_main.c
+++ b/sys/kern/init_main.c
@@ -39,7 +39,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)init_main.c	8.9 (Berkeley) 1/21/94
- * $Id: init_main.c,v 1.101 1998/12/19 08:23:31 julian Exp $
+ * $Id: init_main.c,v 1.102 1998/12/30 10:38:58 dfr Exp $
  */
 
 #include "opt_devfs.h"
@@ -469,22 +469,12 @@ proc0_init(dummy)
 #endif	/* INCOMPAT_LITES2*/
 #endif
 
-#ifndef COMPAT_LINUX_THREADS
 	/*
 	 * We continue to place resource usage info and signal
 	 * actions in the user struct so they're pageable.
 	 */
 	p->p_stats = &p->p_addr->u_stats;
 	p->p_sigacts = &p->p_addr->u_sigacts;
-#else
-	/*
-	 * We continue to place resource usage info in the user struct so
-	 * it's pageable.
-	 */
-	p->p_stats = &p->p_addr->u_stats;
-
-	p->p_sigacts = &p->p_procsig->ps_sigacts;
-#endif /* COMPAT_LINUX_THREADS */
 
 	/*
 	 * Charge root for one process.