Module Name: src
Committed By: kamil
Date: Tue Oct 15 13:59:57 UTC 2019
Modified Files:
src/sys/kern: kern_sig.c
Log Message:
Remove the short-circuit lwp_exit() path from sigswitch()
sigswitch() can be called from exit1() through:
ttywait()->ttysleep()->
cv_timedwait_sig()->sleepq_block()->issignal()->sigswitch()
lwp_exit() called for the last LWP triggers exit1() and this causes a panic.
The debugger related signals have short-circuit demise paths in
eventswitch() and other functions, before calling sigswitch().
This change restores the original behavior, but there is an open question
whether the kernel crash is a red herring of misbehavior of ttywait().
This should fix PR kern/54618 by David H. Gutteridge
To generate a diff of this commit:
cvs rdiff -u -r1.372 -r1.373 src/sys/kern/kern_sig.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/kern_sig.c
diff -u src/sys/kern/kern_sig.c:1.372 src/sys/kern/kern_sig.c:1.373
--- src/sys/kern/kern_sig.c:1.372 Sun Oct 13 03:50:26 2019
+++ src/sys/kern/kern_sig.c Tue Oct 15 13:59:57 2019
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_sig.c,v 1.372 2019/10/13 03:50:26 kamil Exp $ */
+/* $NetBSD: kern_sig.c,v 1.373 2019/10/15 13:59:57 kamil Exp $ */
/*-
* Copyright (c) 2006, 2007, 2008 The NetBSD Foundation, Inc.
@@ -70,7 +70,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_sig.c,v 1.372 2019/10/13 03:50:26 kamil Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_sig.c,v 1.373 2019/10/15 13:59:57 kamil Exp $");
#include "opt_ptrace.h"
#include "opt_dtrace.h"
@@ -1713,21 +1713,6 @@ sigswitch(int ppmask, int signo, bool pr
}
/*
- * If we are exiting, demise now.
- *
- * This avoids notifying tracer and deadlocking.
- */
- if (__predict_false(ISSET(p->p_sflag, PS_WEXIT))) {
- mutex_exit(p->p_lock);
- if (proc_lock_held) {
- mutex_exit(proc_lock);
- }
- lwp_exit(l);
- panic("sigswitch");
- /* NOTREACHED */
- }
-
- /*
* On entry we know that the process needs to stop. If it's
* the result of a 'sideways' stop signal that has been sourced
* through issignal(), then stop other LWPs in the process too.
