[src/trunk]: src/sys/kern On MP, exit postsig() when another LWP has already ...

[cl <cl%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/db208bb2be2e
branches:  trunk
changeset: 559669:db208bb2be2e
user:      cl <cl%NetBSD.org@localhost>
date:      Sun Mar 21 18:41:38 2004 +0000

description:
On MP, exit postsig() when another LWP has already handled the signal while
this LWP was waiting for the kernel lock.

Fixes PR kern/24829

diffstat:

 sys/kern/kern_sig.c |  16 ++++++++++++++--
 1 files changed, 14 insertions(+), 2 deletions(-)

diffs (37 lines):

diff -r de4678638aaf -r db208bb2be2e sys/kern/kern_sig.c
--- a/sys/kern/kern_sig.c       Sun Mar 21 18:19:52 2004 +0000
+++ b/sys/kern/kern_sig.c       Sun Mar 21 18:41:38 2004 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_sig.c,v 1.187 2004/03/14 01:08:47 cl Exp $        */
+/*     $NetBSD: kern_sig.c,v 1.188 2004/03/21 18:41:38 cl Exp $        */
 
 /*
  * Copyright (c) 1982, 1986, 1989, 1991, 1993
@@ -37,7 +37,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_sig.c,v 1.187 2004/03/14 01:08:47 cl Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_sig.c,v 1.188 2004/03/21 18:41:38 cl Exp $");
 
 #include "opt_ktrace.h"
 #include "opt_compat_sunos.h"
@@ -1792,6 +1792,18 @@
 
        KERNEL_PROC_LOCK(l);
 
+#ifdef MULTIPROCESSOR
+       /*
+        * On MP, issignal() can return the same signal to multiple
+        * LWPs.  The LWPs will block above waiting for the kernel
+        * lock and the first LWP which gets through will then remove
+        * the signal from ps_siglist.  All other LWPs exit here.
+        */
+       if (!sigismember(&p->p_sigctx.ps_siglist, signum)) {
+               KERNEL_PROC_UNLOCK(l);
+               return;
+       }
+#endif
        sigdelset(&p->p_sigctx.ps_siglist, signum);
        action = SIGACTION_PS(ps, signum).sa_handler;
        if (action == SIG_DFL) {