From: Louis Rilling <Louis.Rilling@kerlabs.com>
To: Andrey Mirkin <major@openvz.org>
Cc: devel@openvz.org, Pavel Emelyanov <xemul@openvz.org>,
Cedric Le Goater <clg@fr.ibm.com>,
containers@lists.linux-foundation.org,
linux-kernel@vger.kernel.org
Subject: Re: [Devel] Re: [PATCH 08/10] Introduce functions to restart a process
Date: Wed, 22 Oct 2008 11:25:02 +0200 [thread overview]
Message-ID: <20081022092502.GW15171@hawkmoon.kerlabs.com> (raw)
In-Reply-To: <200810221249.55600.major@openvz.org>
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On Wed, Oct 22, 2008 at 12:49:54PM +0400, Andrey Mirkin wrote:
> On Monday 20 October 2008 13:23 Cedric Le Goater wrote:
> > Hello Andrey !
> >
> > > diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
> > > index 109792b..a4848a3 100644
> > > --- a/arch/x86/kernel/entry_32.S
> > > +++ b/arch/x86/kernel/entry_32.S
> > > @@ -225,6 +225,7 @@ ENTRY(ret_from_fork)
> > > GET_THREAD_INFO(%ebp)
> > > popl %eax
> > > CFI_ADJUST_CFA_OFFSET -4
> > > +ret_from_fork_tail:
> > > pushl $0x0202 # Reset kernel eflags
> > > CFI_ADJUST_CFA_OFFSET 4
> > > popfl
> > > @@ -233,6 +234,26 @@ ENTRY(ret_from_fork)
> > > CFI_ENDPROC
> > > END(ret_from_fork)
> > >
> > > +ENTRY(i386_ret_from_resume)
> > > + CFI_STARTPROC
> > > + pushl %eax
> > > + CFI_ADJUST_CFA_OFFSET 4
> > > + call schedule_tail
> > > + GET_THREAD_INFO(%ebp)
> > > + popl %eax
> > > + CFI_ADJUST_CFA_OFFSET -4
> > > + movl (%esp), %eax
> > > + testl %eax, %eax
> > > + jz 1f
> > > + pushl %esp
> > > + call *%eax
> > > + addl $4, %esp
> > > +1:
> > > + addl $256, %esp
> > > + jmp ret_from_fork_tail
> > > + CFI_ENDPROC
> > > +END(i386_ret_from_resume)
> >
> > Could you explain why you need to do this
> >
> > call *%eax
> >
> > is it related to the freezer code ?
>
> It is not related to the freezer code actually.
> That is needed to restart syscalls. Right now I don't have a code in my
> patchset which restarts a syscall, but later I plan to add it.
> In OpenVZ checkpointing we restart syscalls if process was caught in syscall
> during checkpointing.
Do you checkpoint uninterruptible syscalls as well? If only interruptible
syscalls are checkpointed, I'd say that either this syscall uses ERESTARTSYS or
ERESTART_RESTARTBLOCK, and then signal handling code already does the trick, or
this syscall does not restart itself when interrupted, and well, this is life,
userspace just sees -EINTR, which is allowed by the syscall spec.
Actually this is how we checkpoint/migrate tasks in interruptible syscalls in
Kerrighed and this works.
Louis
--
Dr Louis Rilling Kerlabs
Skype: louis.rilling Batiment Germanium
Phone: (+33|0) 6 80 89 08 23 80 avenue des Buttes de Coesmes
http://www.kerlabs.com/ 35700 Rennes
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next prev parent reply other threads:[~2008-10-22 9:25 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-17 23:11 [PATCH 0/10] OpenVZ kernel based checkpointing/restart (v2) Andrey Mirkin
2008-10-17 23:11 ` [PATCH 01/10] Introduce trivial sys_checkpoint and sys_restore system calls Andrey Mirkin
2008-10-17 23:11 ` [PATCH 02/10] Make checkpoint/restart functionality modular Andrey Mirkin
2008-10-17 23:11 ` [PATCH 03/10] Introduce context structure needed during checkpointing/restart Andrey Mirkin
2008-10-17 23:11 ` [PATCH 04/10] Introduce container dump function Andrey Mirkin
2008-10-17 23:11 ` [PATCH 05/10] Introduce function to dump process Andrey Mirkin
2008-10-17 23:11 ` [PATCH 06/10] Introduce functions to dump mm Andrey Mirkin
2008-10-17 23:11 ` [PATCH 07/10] Introduce function for restarting a container Andrey Mirkin
2008-10-17 23:11 ` [PATCH 08/10] Introduce functions to restart a process Andrey Mirkin
2008-10-17 23:11 ` [PATCH 09/10] Introduce functions to restore mm Andrey Mirkin
2008-10-17 23:11 ` [PATCH 10/10] Add support for multiple processes Andrey Mirkin
2008-10-27 15:58 ` Oren Laadan
2008-10-30 4:55 ` [Devel] " Andrey Mirkin
2008-10-20 9:23 ` [PATCH 08/10] Introduce functions to restart a process Cedric Le Goater
2008-10-22 8:49 ` [Devel] " Andrey Mirkin
2008-10-22 9:25 ` Louis Rilling [this message]
2008-10-22 10:06 ` Greg Kurz
2008-10-22 10:44 ` Louis Rilling
2008-10-22 12:44 ` Greg Kurz
2008-10-22 10:12 ` Andrey Mirkin
2008-10-22 10:46 ` Louis Rilling
2008-10-23 8:53 ` Andrey Mirkin
2008-10-22 15:25 ` Oren Laadan
2008-10-23 9:00 ` Andrey Mirkin
2008-10-23 13:57 ` Dave Hansen
2008-10-24 3:57 ` Andrey Mirkin
2008-10-25 21:10 ` Oren Laadan
2008-10-29 14:52 ` Andrey Mirkin
2008-10-30 15:59 ` Oren Laadan
2008-10-22 12:47 ` Cedric Le Goater
2008-10-23 9:54 ` Andrey Mirkin
2008-10-23 13:49 ` Dave Hansen
2008-10-24 4:04 ` Andrey Mirkin
2008-10-20 13:25 ` Louis Rilling
2008-10-23 10:56 ` [Devel] " Andrey Mirkin
2008-10-20 12:25 ` [PATCH 06/10] Introduce functions to dump mm Louis Rilling
2008-10-22 8:58 ` [Devel] " Andrey Mirkin
2008-10-20 17:21 ` Dave Hansen
2008-10-23 8:43 ` [Devel] " Andrey Mirkin
2008-10-23 13:51 ` Dave Hansen
2008-10-24 4:07 ` Andrey Mirkin
2008-10-20 11:02 ` [PATCH 05/10] Introduce function to dump process Louis Rilling
2008-10-24 4:15 ` [Devel] " Andrey Mirkin
2008-10-20 17:48 ` Serge E. Hallyn
2008-10-24 4:40 ` [Devel] " Andrey Mirkin
2008-10-20 17:02 ` [PATCH 03/10] Introduce context structure needed during checkpointing/restart Dave Hansen
2008-10-29 15:30 ` [Devel] " Andrey Mirkin
2008-10-20 16:51 ` [PATCH 02/10] Make checkpoint/restart functionality modular Dave Hansen
2008-10-20 16:59 ` Serge E. Hallyn
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