Date: Sun, 19 Aug 2012 15:26:36 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Jilles Tjoelker <jilles@stack.nl> Cc: freebsd-hackers@freebsd.org, davidxu@freebsd.org Subject: Re: system() using vfork() or posix_spawn() and libthr Message-ID: <20120819122636.GH33100@deviant.kiev.zoral.com.ua> In-Reply-To: <20120817160847.GA34417@stack.nl> References: <20120814094111.GB5883@deviant.kiev.zoral.com.ua> <502A6B7A.6070504@gmail.com> <20120814210911.GA90640@stack.nl> <502AE1D4.4060308@gmail.com> <20120815174942.GN5883@deviant.kiev.zoral.com.ua> <502C3D8B.4060008@gmail.com> <20120816114426.GR5883@deviant.kiev.zoral.com.ua> <20120816223933.GA19925@stack.nl> <20120817124312.GD33100@deviant.kiev.zoral.com.ua> <20120817160847.GA34417@stack.nl>
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On Fri, Aug 17, 2012 at 06:08:47PM +0200, Jilles Tjoelker wrote:
> On Fri, Aug 17, 2012 at 03:43:12PM +0300, Konstantin Belousov wrote:
> > On Fri, Aug 17, 2012 at 12:39:33AM +0200, Jilles Tjoelker wrote:
> > > On Thu, Aug 16, 2012 at 02:44:26PM +0300, Konstantin Belousov wrote:
> > > > BTW, returning to Jilles proposal, can we call vfork() only for
> > > > single-threaded parent ? I think it gives good boost for single-thr=
eaded
> > > > case, and also eliminates the concerns of non-safety.
>=20
> > > This would probably fix the safety issues but at a price. There is a
> > > correlation between processes so large that they benefit greatly from
> > > vfork and threaded processes.
> > Ok, so I will continue with my patch.
>=20
> > > On the other hand, I think direct calls to vfork() in applications are
> > > risky and it may not be possible to support them safely in all
> > > circumstances. However, if libc is calling vfork() such as via popen(=
),
> > > system() or posix_spawn(), it should be possible even in a
> > > multi-threaded process. In that case, the rtld and libthr problems can
> > > be avoided by using aliases with hidden visibility for all functions =
the
> > > vforked child needs to call (or any other method that prevents
> > > interposition and hard-codes a displacement into libc.so).
>=20
> > I do not see how using any aliases could help there. Basically, if mt
> > process is not single-threaded for vfork, you can have both some parent
> > thread and child enter rtld. This is complete mess.
>=20
> If libc calls a function with hidden visibility, this proceeds directly
> (not via the PLT) and rtld is not involved.
Oh, so you are only concerned with libc there ?
If spending so much efforts on this issue, IMO it is pity to only fix
libc and not fix vfork for all consumers.
>=20
> Several ways to do this are in section 2.2.7 Avoid Using Exported
> Symbols of Ulrich Drepper's dsohowto. One of them is something like
>=20
> extern __typeof(next) next_int
> __attribute((alias("next"), visibility("hidden")));
>=20
> in the same source as the definition of the function
>=20
> int next(void) { ...; }
>=20
> As Drepper notes, the visibility attribute is not strictly required if a
> version script keeps the symbol local but it might lead to better code.
> At least on i386, though, the optimal direct near call instruction is
> generated even without it. For example, _nsdispatch() calls
> libc_dlopen() (kept local by the version script) without going through
> the PLT (from the output of objdump -dS on the libc.so.7 in /usr/obj).
I am not confident, so this might be a hallucination, but 'optimization'
in the recent gnu ld might rewrite the call target to avoid PLT when
symbol visibility is hidden.
>=20
> In the assembler syscall stubs using code from lib/libc/arch/SYS.h this
> can be done by adding another .set (we currently have foo, _foo and
> __sys_foo for a syscall foo; some syscalls have only _foo and
> __sys_foo) such as __syshidden_foo. The ones that are actually used
> then need prototypes (similar to the __sys_* ones in lib/libthr/?).
>=20
> For some reason, the symbol .cerror (HIDENAME(cerror)) is also exported.
> Either this should be kept local or a local uninterposable alias should
> be added and used (as with the syscalls).
>=20
> The function __error() (to get errno's address for the current thread)
> is and must be called via the PLT (because libthr is separate).
> Therefore, we should ensure it is called at least once before vfork so
> calls in the child do not involve rtld. The implementations for the
> various architectures use the TLS register (or memory location for ARM),
> so they seem safe.
>=20
> This should suffice to fix posix_spawn() but the _execvpe() used by
> posix_spawnp also uses various string functions. If not all of these
> have already been called earlier, this will not work. Making calls to
> them not go through the PLT seems fairly hard, even though it would make
> sense in general, so perhaps I should instead reimplement it such that
> the parent does almost all of the work.
>=20
> An alternative is to write the core of posix_spawn() in assembler using
> system calls directly but I would rather avoid that :(
BTW, we have very gross inefficiency in our libc syscall stubs on i386.
Namely, the PIC_PROLOGUE generates 'call 1f; 1f:' sequence, which trashes
return stack predictor in CPU. When compiling for pentium pro and later,
gcc calls dummy procedure that moves return address into %ebx. I think
we ought to do this unconditionally for libc stubs in modern times.
>=20
> > > There may still be a problem in programs that install signal handlers
> > > because the set of async-signal-safe functions is larger than what can
> > > be done in a vforked child. Userland can avoid this by masking affect=
ed
> > > signals before calling vfork() and resetting them to SIG_DFL before
> > > unmasking them. This will add many syscalls if the code does not know
> > > which signals are affected (such as libc). Alternatively, the kernel
> > > could map caught signals to the default action for processes with
> > > P_PPWAIT (just like it does not stop such processes because of signals
> > > or TTY job control).
>=20
> > If rtld does not work, then any library function call from a signal han=
dler
> > is problematic. My goal is to get a working rtld and possibly malloc.
>=20
> > BTW, not quite related, it seems that the placement of openat,
> > setcontext and swapcontext in the pthread.map is wrong. openat is
> > at FBSD_1.1 in libc, and *context are at FBSD_1.0 version, while
> > libthr exports them at 1.2. App or library gets linked to arbitrary
> > version depending on whether libphread was specified at link time, and
> > interposition from libthr does not work.
>=20
> Oops :( Can this still be fixed (like by exporting identical functions
> in multiple versions)?
My take is that we shall declare this an ABI bug and fix it before 9.1
by exporting only the right version from libthr. This would indeed break
some binaries, but I having the same symbol at different versions gives
not the semantic we want for bugfix (since you would still link to the
default version).
>=20
> > Below is the latest version of my patch for vfork, which survives (modi=
fied)
> > tools/test/pthread_vfork_test. Patch is only for x86 right now.
>=20
> Why does this patch call thread_single(SINGLE_BOUNDARY)? I think this
> just causes breakage by causing short writes, [ERESTART] and the like
> where not permitted by POSIX while not fixing userland's problems. From
> userland's point of view, thread_single(SINGLE_BOUNDARY) just freezes
> threads at whatever point they are executing, including while holding an
> internal lock. Also, the thread_single_end() is before waiting for the
> child to exec or exit (because that is now just before returning to
> userland).
Oh, the placement of the single_end() is bug. Thank you for noting it.
The EINTR return from syscalls in other threads when doing fork(2) in
one thread is common and well-known situation. I believe that older
Solarises and SVr4 did exactly this. So I do not consider the EINTR or
short i/o an unacceptable cost, but please see below.
>=20
> If single-threading is needed, it should be done in userland such as via
> pthread_suspend_all_np(). This function already ensures no other thread
> is in a libthr critical section. If rtld blocks SIGTHR during its
> critical sections, it likely also waits for the threads to leave rtld.
> As with kernel-level single-threading, this is slow and causes incorrect
> short writes.
User-mode single-threading, like pthread_suspend_all_np() is order of
magnitude slower then kernel-mode single-threading (I admit that I was
not aware of pthread_suspend_all_np()).
The cause is that kernel often can declare single-threading done when
the threads are stopped while still on sleepqueue. Only recently we started
marking some sleeps as 'unsafe to stop', mostly in NFS land.
So pthread_suspend_all_np() needs to wake up all threads, deliver SIGCANCEL,
wait for threads to leave kernel and get ast. For large process were lot
of threads typically just sleep waiting for (socket) i/o, there is a lot
of cycles to spend.
>=20
> If single-threading is only necessary because umtx locks are formally
> per-process instead of per-vmspace, then I suggest avoiding the trouble
> and depending on the fact that they are per-vmspace.
I agree. I worried about inter-process locking to prevent simultaneous
entry into rtld or malloc from parent other thread and child, but as
David rightfully pointed out, still relied on single vmspace for unlock.
So I removed the single-threading from the kernel, relying on the usermode
locks to prevent parallel rtld entrance and to lock fork/vfork in parent.
Patch below also fixes a typo in amd64/vfork.S, which also passes
pthread_vfork_test now.
diff --git a/lib/libthr/arch/amd64/Makefile.inc b/lib/libthr/arch/amd64/Mak=
efile.inc
index e6d99ec..476d26a 100644
--- a/lib/libthr/arch/amd64/Makefile.inc
+++ b/lib/libthr/arch/amd64/Makefile.inc
@@ -1,3 +1,4 @@
#$FreeBSD$
=20
-SRCS+=3D pthread_md.c _umtx_op_err.S
+CFLAGS+=3D-I${.CURDIR}/../libc/${MACHINE_CPUARCH}
+SRCS+=3D pthread_md.c _umtx_op_err.S vfork.S
diff --git a/lib/libthr/arch/amd64/amd64/vfork.S b/lib/libthr/arch/amd64/am=
d64/vfork.S
new file mode 100644
index 0000000..7997032
--- /dev/null
+++ b/lib/libthr/arch/amd64/amd64/vfork.S
@@ -0,0 +1,77 @@
+/*-
+ * Copyright (c) 2012 Konstantin Belousov <kib@freebsd.org>
+ * Copyright (c) 1990 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * William Jolitz.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURP=
OSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENT=
IAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STR=
ICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY W=
AY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <machine/asm.h>
+__FBSDID("$FreeBSD$");
+
+#include "SYS.h"
+
+ .weak _vfork
+ .set _vfork,__sys_vfork
+ .weak vfork
+ .set vfork,__sys_vfork
+ENTRY(__sys_vfork)
+ call _thr_vfork_pre
+ popq %rsi /* fetch return address (%rsi preserved) */
+ mov $SYS_vfork,%rax
+ KERNCALL
+ jb 2f
+ cmpl $0,%eax
+ jne 1f
+ pushq %rsi
+ pushq %rsi /* twice for stack alignment */
+ call CNAME(_thr_vfork_post_child)
+ popq %rsi
+ popq %rsi
+ xorl %eax,%eax
+ jmp *%rsi
+1:
+ pushq %rsi
+ pushq %rax
+ call CNAME(_thr_vfork_post_parent)
+ popq %rax
+ popq %rsi
+ jmp *%rsi
+2:
+ pushq %rsi
+ pushq %rax
+ call CNAME(_thr_vfork_post_child)
+ call PIC_PLT(CNAME(__error))
+ popq %rdx
+ movq %rdx,(%rax)
+ movq $-1,%rax
+ movq %rax,%rdx
+ retq
+END(__sys_vfork)
+
+ .section .note.GNU-stack,"",%progbits
diff --git a/lib/libthr/arch/i386/Makefile.inc b/lib/libthr/arch/i386/Makef=
ile.inc
index 01290d5..13d55e2 100644
--- a/lib/libthr/arch/i386/Makefile.inc
+++ b/lib/libthr/arch/i386/Makefile.inc
@@ -1,3 +1,4 @@
# $FreeBSD$
=20
-SRCS+=3D pthread_md.c _umtx_op_err.S
+CFLAGS+=3D-I${.CURDIR}/../libc/${MACHINE_CPUARCH}
+SRCS+=3D pthread_md.c _umtx_op_err.S vfork.S
diff --git a/lib/libthr/arch/i386/i386/vfork.S b/lib/libthr/arch/i386/i386/=
vfork.S
new file mode 100644
index 0000000..ca8896b
--- /dev/null
+++ b/lib/libthr/arch/i386/i386/vfork.S
@@ -0,0 +1,82 @@
+/*-
+ * Copyright (c) 2012 Konstantin Belousov <kib@freebsd.org>
+ * Copyright (c) 1990 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * William Jolitz.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURP=
OSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENT=
IAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STR=
ICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY W=
AY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <machine/asm.h>
+__FBSDID("$FreeBSD$");
+
+#include "SYS.h"
+
+ .weak _vfork
+ .set _vfork,__sys_vfork
+ .weak vfork
+ .set vfork,__sys_vfork
+ENTRY(__sys_vfork)
+ PIC_PROLOGUE
+ call PIC_PLT(CNAME(_thr_vfork_pre))
+ PIC_EPILOGUE
+ popl %ecx /* my rta into ecx */
+ mov $SYS_vfork,%eax
+ KERNCALL
+ jb error_ret
+ pushl %ecx
+ cmpl $0,%eax
+ jne parent_ret
+ PIC_PROLOGUE
+ call PIC_PLT(CNAME(_thr_vfork_post_child))
+ PIC_EPILOGUE
+ popl %ecx
+ xorl %eax,%eax
+ jmp *%ecx
+parent_ret:
+ pushl %eax
+ PIC_PROLOGUE
+ call PIC_PLT(CNAME(_thr_vfork_post_parent))
+ PIC_EPILOGUE
+ popl %eax
+ popl %ecx
+ jmp *%ecx
+error_ret:
+ pushl %ecx
+ pushl %eax
+ PIC_PROLOGUE
+ call PIC_PLT(CNAME(_thr_vfork_post_child))
+ call PIC_PLT(CNAME(__error))
+ PIC_EPILOGUE
+ popl %edx
+ movl %edx,(%eax)
+ movl $-1,%eax
+ movl %eax,%edx
+ retl
+END(__sys_vfork)
+
+ .section .note.GNU-stack,"",%progbits
diff --git a/lib/libthr/pthread.map b/lib/libthr/pthread.map
index 355edea..40d14b4 100644
--- a/lib/libthr/pthread.map
+++ b/lib/libthr/pthread.map
@@ -157,6 +157,7 @@ FBSD_1.0 {
system;
tcdrain;
usleep;
+ vfork;
wait;
wait3;
wait4;
diff --git a/lib/libthr/thread/Makefile.inc b/lib/libthr/thread/Makefile.inc
index ddde6e9..92e82ac 100644
--- a/lib/libthr/thread/Makefile.inc
+++ b/lib/libthr/thread/Makefile.inc
@@ -55,4 +55,5 @@ SRCS+=3D \
thr_switch_np.c \
thr_symbols.c \
thr_umtx.c \
+ thr_vfork.c \
thr_yield.c
diff --git a/lib/libthr/thread/thr_private.h b/lib/libthr/thread/thr_privat=
e.h
index ba272fe..951c3b8 100644
--- a/lib/libthr/thread/thr_private.h
+++ b/lib/libthr/thread/thr_private.h
@@ -757,6 +757,7 @@ void _thr_cancel_leave(struct pthread *, int) __hidden;
void _thr_testcancel(struct pthread *) __hidden;
void _thr_signal_block(struct pthread *) __hidden;
void _thr_signal_unblock(struct pthread *) __hidden;
+void _thr_signal_unblock_noref(struct pthread *) __hidden;
void _thr_signal_init(void) __hidden;
void _thr_signal_deinit(void) __hidden;
int _thr_send_sig(struct pthread *, int sig) __hidden;
@@ -777,6 +778,9 @@ int _thr_setscheduler(lwpid_t, int, const struct sched_=
param *) __hidden;
void _thr_signal_prefork(void) __hidden;
void _thr_signal_postfork(void) __hidden;
void _thr_signal_postfork_child(void) __hidden;
+void _thr_vfork_pre(void) __hidden;
+void _thr_vfork_post_child(void) __hidden;
+void _thr_vfork_post_parent(void) __hidden;
void _thr_try_gc(struct pthread *, struct pthread *) __hidden;
int _rtp_to_schedparam(const struct rtprio *rtp, int *policy,
struct sched_param *param) __hidden;
@@ -833,6 +837,7 @@ pid_t __sys_getpid(void);
ssize_t __sys_read(int, void *, size_t);
ssize_t __sys_write(int, const void *, size_t);
void __sys_exit(int);
+pid_t __sys_vfork(void);
#endif
=20
static inline int
diff --git a/lib/libthr/thread/thr_sig.c b/lib/libthr/thread/thr_sig.c
index 3dee8b7..3e5b25e 100644
--- a/lib/libthr/thread/thr_sig.c
+++ b/lib/libthr/thread/thr_sig.c
@@ -107,6 +107,13 @@ _thr_signal_unblock(struct pthread *curthread)
__sys_sigprocmask(SIG_SETMASK, &curthread->sigmask, NULL);
}
=20
+void
+_thr_signal_unblock_noref(struct pthread *curthread)
+{
+ if (curthread->sigblock =3D=3D 0)
+ __sys_sigprocmask(SIG_SETMASK, &curthread->sigmask, NULL);
+}
+
int
_thr_send_sig(struct pthread *thread, int sig)
{
diff --git a/lib/libthr/thread/thr_vfork.c b/lib/libthr/thread/thr_vfork.c
new file mode 100644
index 0000000..80c9d1e
--- /dev/null
+++ b/lib/libthr/thread/thr_vfork.c
@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) 2012 Konstantin Belousov <kib@freebsd.org>
+ * Copyright (c) 2005 David Xu <davidxu@freebsd.org>
+ * Copyright (c) 2003 Daniel Eischen <deischen@freebsd.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Neither the name of the author nor the names of any co-contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURP=
OSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENT=
IAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STR=
ICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY W=
AY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+/*
+ * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the author nor the names of any co-contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURP=
OSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENT=
IAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STR=
ICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY W=
AY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include "namespace.h"
+#include <errno.h>
+#include <link.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <spinlock.h>
+#include "un-namespace.h"
+
+#include "libc_private.h"
+#include "rtld_lock.h"
+#include "thr_private.h"
+
+static int rtld_locks[MAX_RTLD_LOCKS];
+static int cancelsave, was_threaded;
+
+void
+_thr_vfork_pre(void)
+{
+ struct pthread *curthread;
+
+ curthread =3D _get_curthread();
+ _thr_rwl_wrlock(&_thr_atfork_lock);
+ cancelsave =3D curthread->no_cancel;
+ curthread->no_cancel =3D 1;
+ _thr_signal_block(curthread);
+ _thr_signal_prefork();
+ if (_thr_isthreaded() !=3D 0) {
+ was_threaded =3D 1;
+ _malloc_prefork();
+ _rtld_atfork_pre(rtld_locks);
+ } else
+ was_threaded =3D 0;
+}
+
+void
+_thr_vfork_post_child(void)
+{
+ struct pthread *curthread;
+
+ _thr_signal_postfork();
+ if (was_threaded) {
+ _rtld_atfork_post(rtld_locks);
+ _malloc_postfork();
+ }
+ curthread =3D _get_curthread();
+ _thr_signal_unblock(curthread);
+ curthread->no_cancel =3D cancelsave;
+ _thr_rwlock_unlock(&_thr_atfork_lock);
+ if (curthread->cancel_async)
+ _thr_testcancel(curthread);
+}
+
+void
+_thr_vfork_post_parent(void)
+{
+ struct pthread *curthread;
+
+ curthread =3D _get_curthread();
+ _thr_signal_unblock_noref(curthread);
+ if (curthread->cancel_async)
+ _thr_testcancel(curthread);
+}
diff --git a/sys/kern/kern_fork.c b/sys/kern/kern_fork.c
index 46cdca1..6f2cfed 100644
--- a/sys/kern/kern_fork.c
+++ b/sys/kern/kern_fork.c
@@ -150,11 +150,7 @@ sys_vfork(struct thread *td, struct vfork_args *uap)
int error, flags;
struct proc *p2;
=20
-#ifdef XEN
- flags =3D RFFDG | RFPROC; /* validate that this is still an issue */
-#else
flags =3D RFFDG | RFPROC | RFPPWAIT | RFMEM;
-#endif =09
error =3D fork1(td, flags, 0, &p2, NULL, 0);
if (error =3D=3D 0) {
td->td_retval[0] =3D p2->p_pid;
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