From bf189c26eef6d4c0eddb382f269c593999439812 Mon Sep 17 00:00:00 2001
From: Matthew Dillon <dillon@dragonflybsd.org>
Date: Thu, 1 Dec 2005 18:54:20 +0000
Subject: [PATCH] For MPSAFE syscall operation, CURSIG->__cursig->issignal()
 may be called without the MP lock held.  At the moment issignal() needs to be
 MP locked so wrap the function in the lock.  Note that issignal() is only
 called if there is a signal pending so this will not disrupt
 kern.syscall_mpsafe operation.

---
 sys/kern/kern_sig.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
index 128a398bfe..c2a0488673 100644
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -37,7 +37,7 @@
  *
  *	@(#)kern_sig.c	8.7 (Berkeley) 4/18/94
  * $FreeBSD: src/sys/kern/kern_sig.c,v 1.72.2.17 2003/05/16 16:34:34 obrien Exp $
- * $DragonFly: src/sys/kern/kern_sig.c,v 1.40 2005/12/01 18:30:08 dillon Exp $
+ * $DragonFly: src/sys/kern/kern_sig.c,v 1.41 2005/12/01 18:54:20 dillon Exp $
  */
 
 #include "opt_ktrace.h"
@@ -1230,6 +1230,9 @@ iscaught(struct proc *p)
  * by checking the pending signal masks in the CURSIG macro.) The normal call
  * sequence is
  *
+ * This routine is called via CURSIG/__cursig and the MP lock might not be
+ * held.  Obtain the MP lock for the duration of the operation.
+ *
  *	while (sig = CURSIG(curproc))
  *		postsig(sig);
  */
@@ -1239,6 +1242,7 @@ issignal(struct proc *p)
 	sigset_t mask;
 	int sig, prop;
 
+	get_mplock();
 	for (;;) {
 		int traced = (p->p_flag & P_TRACED) || (p->p_stops & S_SIG);
 
@@ -1246,8 +1250,10 @@ issignal(struct proc *p)
 		SIGSETNAND(mask, p->p_sigmask);
 		if (p->p_flag & P_PPWAIT)
 			SIG_STOPSIGMASK(mask);
-		if (!SIGNOTEMPTY(mask))	 	/* no signal to send */
+		if (!SIGNOTEMPTY(mask)) { 	/* no signal to send */
+			rel_mplock();
 			return (0);
+		}
 		sig = sig_ffs(&mask);
 
 		STOPEVENT(p, S_SIG, sig);
@@ -1367,6 +1373,7 @@ issignal(struct proc *p)
 				 */
 				break;		/* == ignore */
 			} else {
+				rel_mplock();
 				return (sig);
 			}
 
@@ -1388,6 +1395,7 @@ issignal(struct proc *p)
 			 * This signal has an action, let
 			 * postsig() process it.
 			 */
+			rel_mplock();
 			return (sig);
 		}
 		SIGDELSET(p->p_siglist, sig);		/* take the signal! */
-- 
2.11.4.GIT