Date: Mon, 12 Mar 2001 18:46:16 -0500 From: James FitzGibbon <james@ehlo.com> To: KUROSAWA Takahiro <fwkg7679@mb.infoweb.ne.jp>, Daniel Eischen <eischen@vigrid.com> Cc: current@freebsd.org Subject: Fixed - pthread altsigstack problem Message-ID: <20010312184616.A25098@ehlo.com>
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Both of the patches below fix the problem mentioned in PR bin/25110. The
first one fixes it inside of kern_fork.c and would appear to apply the
corrective behaviour regardless of whether the process uses libc_r or not.
The second patch fixes the problem inside of uthread_fork.c. Whether the
first approach imposes an extra cost on non-threaded applications I'm not
kernel-experienced enough to say, but hopefully between two of you gents you
can decide which is the better fix to apply.
As I mentioned in my original post, this is a bug that we are experiencing
in 4.3-BETA, so if this could make it into 4.3-RELEASE it would be of great
help. One note regarding the second (libc_r) patch: the reference to
__sys_sigaltstack needs to be changed to _thread_sys_sigaltstack in order to
prevent undefined symbols on 4.x systems.
Patch #1 (kernel fix):
--- kern_fork.c.orig Sat Mar 10 12:17:40 2001
+++ kern_fork.c Sat Mar 10 12:20:39 2001
@@ -434,7 +434,7 @@
* Preserve some more flags in subprocess. P_PROFIL has already
* been preserved.
*/
- p2->p_flag |= p1->p_flag & P_SUGID;
+ p2->p_flag |= p1->p_flag & (P_SUGID | P_ALTSTACK);
if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT)
p2->p_flag |= P_CONTROLT;
if (flags & RFPPWAIT)
Patch #2 (libc_r fix):
--- uthread_fork.c 2001/01/24 13:03:33 1.21
+++ uthread_fork.c 2001/03/09 17:53:37
@@ -32,6 +32,7 @@
* $FreeBSD: src/lib/libc_r/uthread/uthread_fork.c,v 1.21 2001/01/24 13:03:33 deischen Exp $
*/
#include <errno.h>
+#include <signal.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
@@ -110,7 +111,16 @@
else if (_pq_init(&_readyq) != 0) {
/* Abort this application: */
PANIC("Cannot initialize priority ready queue.");
- } else {
+ } else if ((_thread_sigstack.ss_sp == NULL) &&
+ ((_thread_sigstack.ss_sp = malloc(SIGSTKSZ)) == NULL))
+ PANIC("Unable to allocate alternate signal stack");
+ else {
+ /* Install the alternate signal stack: */
+ _thread_sigstack.ss_size = SIGSTKSZ;
+ _thread_sigstack.ss_flags = 0;
+ if (__sys_sigaltstack(&_thread_sigstack, NULL) != 0)
+ PANIC("Unable to install alternate signal stack");
+
/*
* Enter a loop to remove all threads other than
* the running thread from the thread list:
Thanks for the help guys.
--
j.
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