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>

8 files changed, 81 insertions, 61 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.
diff --git a/sys/kern/kern_exit.c b/sys/kern/kern_exit.c
index 7de0c48..7be01af 100644
--- a/sys/kern/kern_exit.c
+++ b/sys/kern/kern_exit.c
@@ -36,7 +36,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)kern_exit.c	8.7 (Berkeley) 2/12/94
- * $Id: kern_exit.c,v 1.69 1998/11/11 10:03:54 truckman Exp $
+ * $Id: kern_exit.c,v 1.70 1998/12/19 02:55:33 julian Exp $
  */
 
 #include "opt_compat.h"
@@ -73,6 +73,9 @@
 #include <vm/pmap.h>
 #include <vm/vm_map.h>
 #include <vm/vm_zone.h>
+#ifdef COMPAT_LINUX_THREADS
+#include <sys/user.h>
+#endif
 
 static MALLOC_DEFINE(M_ZOMBIE, "zombie", "zombie proc status");
 
@@ -438,14 +441,6 @@ loop:
 		if (uap->pid != WAIT_ANY &&
 		    p->p_pid != uap->pid && p->p_pgid != -uap->pid)
 			continue;
-#ifdef COMPAT_LINUX_THREADS
-		#if 0
-		if ((p->p_sigparent != 0) ^ ((uap->options & WLINUXCLONE) != 0)) {
-			continue;
-		}
-		#endif
-
-#endif /* COMPAT_LINUX_THREADS */
 		nfound++;
 		if (p->p_stat == SZOMB) {
 			/* charge childs scheduling cpu usage to parent */
@@ -515,11 +510,11 @@ loop:
 
 #ifdef COMPAT_LINUX_THREADS
 			if (--p->p_procsig->ps_refcnt == 0) {
-			        free(p->p_procsig, M_TEMP);
+				if (p->p_sigacts != &p->p_addr->u_sigacts)
+					FREE(p->p_sigacts, M_SUBPROC);
+			        FREE(p->p_procsig, M_SUBPROC);
 				p->p_procsig = NULL;
-				p->p_sigacts = NULL;
 			}
-
 #endif /* COMPAT_LINUX_THREADS */
 			/*
 			 * Give machine-dependent layer a chance
@@ -576,11 +571,6 @@ proc_reparent(child, parent)
 	LIST_REMOVE(child, p_sibling);
 	LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
 	child->p_pptr = parent;
-#ifdef COMPAT_LINUX_THREADS
-	#if 0
-	child->p_sigparent = 0;
-	#endif
-#endif /* COMPAT_LINUX_THREADS */
 }
 
 /*
@@ -636,3 +626,22 @@ rm_at_exit(function)
 	}
 	return (count);
 }
+
+#ifdef COMPAT_LINUX_THREADS
+void check_sigacts (void)
+{
+	struct proc *p = curproc;
+	struct sigacts *pss;
+	int s;
+
+	if (p->p_procsig->ps_refcnt == 1 &&
+	    p->p_sigacts != &p->p_addr->u_sigacts) {
+		pss = p->p_sigacts;
+		s = splhigh();
+		p->p_addr->u_sigacts = *pss;
+		p->p_sigacts = &p->p_addr->u_sigacts;
+		splx(s);
+		FREE(pss, M_SUBPROC);
+	}
+}
+#endif
diff --git a/sys/kern/kern_fork.c b/sys/kern/kern_fork.c
index ef38e01..732712b 100644
--- a/sys/kern/kern_fork.c
+++ b/sys/kern/kern_fork.c
@@ -36,7 +36,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)kern_fork.c	8.6 (Berkeley) 4/8/94
- * $Id: kern_fork.c,v 1.52 1998/11/09 15:07:41 truckman Exp $
+ * $Id: kern_fork.c,v 1.53 1998/12/19 02:55:33 julian Exp $
  */
 
 #include "opt_ktrace.h"
@@ -64,7 +64,7 @@
 
 #ifdef COMPAT_LINUX_THREADS
 #include <machine/frame.h>
-
+#include <sys/user.h>
 #endif /* COMPAT_LINUX_THREADS */
 #ifdef SMP
 static int	fast_vfork = 0;	/* Doesn't work on SMP yet. */
@@ -331,21 +331,41 @@ again:
 
 #ifdef COMPAT_LINUX_THREADS
 	if (flags & RFSIGSHARE) {
+		p2->p_procsig = p1->p_procsig;
 		p2->p_procsig->ps_refcnt++;
+		if (p1->p_sigacts == &p1->p_addr->u_sigacts) {
+			struct sigacts *newsigacts;
+			int s;
+
+			if (p2->p_procsig->ps_refcnt != 2)
+				printf ("PID:%d Creating shared sigacts with procsig->ps_refcnt %d\n",
+					p2->p_pid, p2->p_procsig->ps_refcnt);
+			/* Create the shared sigacts structure */
+			MALLOC (newsigacts, struct sigacts *, sizeof (struct sigacts),
+				M_SUBPROC, M_WAITOK);
+			s = splhigh();
+			/* Set p_sigacts to the new shared structure.  Note that this
+			 * is updating p1->p_sigacts at the same time, since p_sigacts
+			 * is just a pointer to the shared p_procsig->ps_sigacts.
+			 */
+			p2->p_sigacts  = newsigacts;
+			/* Copy in the values from the u area */
+			*p2->p_sigacts = p1->p_addr->u_sigacts;
+			splx (s);
+		}
 	} else {
-		p2->p_procsig = malloc(sizeof(struct procsig), M_TEMP, M_WAITOK);
-		p2->p_procsig->ps_refcnt = 1;
-		p2->p_procsig->ps_posix  = 0;
+		MALLOC (p2->p_procsig, struct procsig *, sizeof(struct procsig),
+			M_SUBPROC, M_WAITOK);
 		bcopy(&p1->p_procsig->ps_begincopy, &p2->p_procsig->ps_begincopy,
 			(unsigned)&p1->p_procsig->ps_endcopy -
 			(unsigned)&p1->p_procsig->ps_begincopy);
+		p2->p_procsig->ps_refcnt = 1;
+		/* Note that we fill in the values of sigacts in vm_fork */
+		p2->p_sigacts = NULL;
 	}
 	if (flags & RFLINUXTHPN) {
 	        p2->p_sigparent = SIGUSR1;
 	}
-	p2->p_sigacts = &p2->p_procsig->ps_sigacts;
-	if((flags & RFTHREAD) != 0 && (flags & RFPOSIXSIG) != 0)
-	        p2->p_procsig->ps_posix = 1;
 #endif /* COMPAT_LINUX_THREADS */
 	/* bump references to the text vnode (for procfs) */
 	p2->p_textvp = p1->p_textvp;
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index d590b42..1b7d5ad 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -36,7 +36,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)proc.h	8.15 (Berkeley) 5/19/95
- * $Id: proc.h,v 1.64 1998/12/21 07:41:50 dillon Exp $
+ * $Id: proc.h,v 1.65 1998/12/31 13:23:16 bde Exp $
  */
 
 #ifndef _SYS_PROC_H_
@@ -86,13 +86,11 @@ struct	procsig {
 #define ps_begincopy ps_sigignore
 	sigset_t ps_sigignore;	/* Signals being ignored. */
 	sigset_t ps_sigcatch;	/* Signals being caught by user. */
-        int      ps_flag;
-	struct	 sigacts ps_sigacts;
+	int      ps_flag;
+	struct	 sigacts *ps_sigacts;
 #define ps_endcopy ps_refcnt
 	int	 ps_refcnt;
-        int      ps_posix;
 };
-
 #endif /* COMPAT_LINUX_THREADS */
 
 /*
@@ -125,7 +123,14 @@ struct	proc {
 	struct	pstats *p_stats;	/* Accounting/statistics (PROC ONLY). */
 	struct	plimit *p_limit;	/* Process limits. */
 	struct	vm_object *p_upages_obj;/* Upages object */
+#ifndef COMPAT_LINUX_THREADS
 	struct	sigacts *p_sigacts;	/* Signal actions, state (PROC ONLY). */
+#else
+	struct	procsig *p_procsig;
+#define p_sigacts	p_procsig->ps_sigacts
+#define p_sigignore	p_procsig->ps_sigignore
+#define p_sigcatch	p_procsig->ps_sigcatch
+#endif
 
 #define	p_ucred		p_cred->pc_ucred
 #define	p_rlimit	p_limit->pl_rlimit
@@ -201,22 +206,12 @@ struct	proc {
 #define	p_endzero	p_startcopy
 
 /* The following fields are all copied upon creation in fork. */
-#ifndef COMPAT_LINUX_THREADS
 #define	p_startcopy	p_sigmask
-#else
-#define	p_startcopy	p_procsig
-#endif /* COMPAT_LINUX_THREADS */
 
-#ifdef COMPAT_LINUX_THREADS
-	struct	procsig *p_procsig;
-#define p_sigignore p_procsig->ps_sigignore
-#define p_sigcatch p_procsig->ps_sigcatch
-#endif /* COMPAT_LINUX_THREADS */
 	sigset_t p_sigmask;	/* Current signal mask. */
 #ifndef COMPAT_LINUX_THREADS
 	sigset_t p_sigignore;	/* Signals being ignored. */
 	sigset_t p_sigcatch;	/* Signals being caught by user. */
-
 #endif /* COMPAT_LINUX_THREADS */
 	u_char	p_priority;	/* Process priority. */
 	u_char	p_usrpri;	/* User-priority based on p_cpu and p_nice. */
diff --git a/sys/sys/signalvar.h b/sys/sys/signalvar.h
index a97f950..658c6cb 100644
--- a/sys/sys/signalvar.h
+++ b/sys/sys/signalvar.h
@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)signalvar.h	8.6 (Berkeley) 2/19/95
- * $Id: signalvar.h,v 1.20 1998/11/11 10:04:13 truckman Exp $
+ * $Id: signalvar.h,v 1.21 1998/12/19 02:55:34 julian Exp $
  */
 
 #ifndef	_SYS_SIGNALVAR_H_		/* tmp for user.h */
@@ -175,7 +175,9 @@ void	psignal __P((struct proc *p, int sig));
 void	sigexit __P((struct proc *p, int signum));
 void	siginit __P((struct proc *p));
 void	trapsignal __P((struct proc *p, int sig, u_long code));
-
+#ifdef COMPAT_LINUX_THREADS
+void check_sigacts (void);
+#endif
 /*
  * Machine-dependent functions:
  */
diff --git a/sys/sys/unistd.h b/sys/sys/unistd.h
index 17b2028..d621603 100644
--- a/sys/sys/unistd.h
+++ b/sys/sys/unistd.h
@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)unistd.h	8.2 (Berkeley) 1/7/94
- * $Id: unistd.h,v 1.17 1998/03/28 11:51:01 dufault Exp $
+ * $Id: unistd.h,v 1.18 1998/12/19 02:55:34 julian Exp $
  */
 
 #ifndef _SYS_UNISTD_H_
@@ -187,7 +187,6 @@
 #define RFCFDG		(1<<12) /* zero fd table */
 #define RFTHREAD	(1<<13)	/* enable kernel thread support */
 #define RFSIGSHARE	(1<<14)	/* share signal handlers */
-#define RFPOSIXSIG      (1<<15) /* UNIMPL posix thread signal delivery */
 #define RFLINUXTHPN     (1<<16) /* do linux clone exit parent notification */
 #define RFPPWAIT	(1<<31) /* parent sleeps until child exits (vfork) */
 
diff --git a/sys/sys/user.h b/sys/sys/user.h
index f97891c..df67154 100644
--- a/sys/sys/user.h
+++ b/sys/sys/user.h
@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)user.h	8.2 (Berkeley) 9/23/93
- * $Id: user.h,v 1.16 1998/07/15 20:18:00 dfr Exp $
+ * $Id: user.h,v 1.17 1998/12/19 02:55:34 julian Exp $
  */
 
 #ifndef _SYS_USER_H_
@@ -101,12 +101,8 @@ void fill_eproc __P((struct proc *, struct eproc *));
 
 struct	user {
 	struct	pcb u_pcb;
-
-#ifndef COMPAT_LINUX_THREADS
 	struct	sigacts u_sigacts;	/* p_sigacts points here (use it!) */
-#endif /* COMPAT_LINUX_THREADS */
 	struct	pstats u_stats;		/* p_stats points here (use it!) */
-
 	/*
 	 * Remaining fields only for core dump and/or ptrace--
 	 * not valid at other times!
diff --git a/sys/vm/vm_glue.c b/sys/vm/vm_glue.c
index ce4786f..ec844db 100644
--- a/sys/vm/vm_glue.c
+++ b/sys/vm/vm_glue.c
@@ -59,7 +59,7 @@
  * any improvements or extensions that they make and grant Carnegie the
  * rights to redistribute these changes.
  *
- * $Id: vm_glue.c,v 1.78 1998/12/19 02:55:34 julian Exp $
+ * $Id: vm_glue.c,v 1.79 1998/12/19 08:23:31 julian Exp $
  */
 
 #include "opt_rlimit.h"
@@ -243,8 +243,17 @@ vm_fork(p1, p2, flags)
 	 * p_stats currently points at fields in the user struct
 	 * but not at &u, instead at p_addr. Copy parts of
 	 * p_stats; zero the rest of p_stats (statistics).
+	 *
+	 * If procsig->ps_refcnt is 1 and p2->p_sigacts is NULL we dont' need
+	 * to share sigacts, so we use the up->u_sigacts.
 	 */
 	p2->p_stats = &up->u_stats;
+	if (p2->p_sigacts == NULL) {
+		if (p2->p_procsig->ps_refcnt != 1)
+			printf ("PID:%d NULL sigacts with refcnt not 1!\n",p2->p_pid);
+		p2->p_sigacts = &up->u_sigacts;
+		up->u_sigacts = *p1->p_sigacts;
+	}
 #endif /* COMPAT_LINUX_THREADS */
 	bzero(&up->u_stats.pstat_startzero,
 	    (unsigned) ((caddr_t) &up->u_stats.pstat_endzero -