Re: [PATCH 2/9] Make checkpoint/restart functionality modular

Andrey Mirkin
2008-09-03T14:48:44Z

On Wednesday 03 September 2008 18:27 Serge E. Hallyn wrote:
> Quoting Andrey Mirkin (major@openvz.org):
> > A config option CONFIG_CHECKPOINT is introduced.
> > New structure cpt_operations is introduced to store pointers to
> > checkpoint/restart functions from module.
>
> Thanks Andrey. The structure of this patchset is very nice, and I'm
> finding it very easy to read, at least the first half.
>
> The differences (in yours and Oren's) between checkpointing and
> restarting yourself or another task should probably not be important
> as people will want to be able to do both in the end, and I'm sure
> both patchsets can do both. And you have things like your own
> printk helpers in patch 3 that, just as in Oren's set, will have to
> go away. But I'm not yet able to see what the real differences are.
>
> Keeping on looking...

Thanks for reviewing. My owen printk is just for debug purpose, I will change
them to something already existing.
I'm waiting for more comments from you.

Thanks,
Andrey

>
> > Signed-off-by: Andrey Mirkin <major@openvz.org>
> > ---
> > cpt/Kconfig | 7 +++++++
> > cpt/Makefile | 4 ++++
> > cpt/cpt.h | 19 +++++++++++++++++++
> > cpt/sys.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
> > cpt/sys_core.c | 29 +++++++++++++++++++++++++++--
> > init/Kconfig | 2 ++
> > 6 files changed, 107 insertions(+), 2 deletions(-)
> > create mode 100644 cpt/Kconfig
> > create mode 100644 cpt/cpt.h
> > create mode 100644 cpt/sys.c
> >
> > diff --git a/cpt/Kconfig b/cpt/Kconfig
> > new file mode 100644
> > index 0000000..b9bc72d
> > --- /dev/null
> > +++ b/cpt/Kconfig
> > @@ -0,0 +1,7 @@
> > +config CHECKPOINT
> > + tristate "Checkpoint & restart for containers"
> > + depends on EXPERIMENTAL
> > + default n
> > + help
> > + This option adds module "cptrst", which allow to save a running
> > + container to a file and restart it later using this image file.
> > diff --git a/cpt/Makefile b/cpt/Makefile
> > index 2276fb1..bfe75d5 100644
> > --- a/cpt/Makefile
> > +++ b/cpt/Makefile
> > @@ -1 +1,5 @@
> > obj-y += sys_core.o
> > +
> > +obj-$(CONFIG_CHECKPOINT) += cptrst.o
> > +
> > +cptrst-objs := sys.o
> > diff --git a/cpt/cpt.h b/cpt/cpt.h
> > new file mode 100644
> > index 0000000..381a9bf
> > --- /dev/null
> > +++ b/cpt/cpt.h
> > @@ -0,0 +1,19 @@
> > +/*
> > + * Copyright (C) 2008 Parallels, Inc.
> > + *
> > + * Author: Andrey Mirkin <major@openvz.org>
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify it under the terms of the GNU General Public License as
> > + * published by the Free Software Foundation, version 2 of the
> > + * License.
> > + *
> > + */
> > +
> > +struct cpt_operations
> > +{
> > + struct module * owner;
> > + int (*checkpoint)(pid_t pid, int fd, unsigned long flags);
> > + int (*restart)(int ctid, int fd, unsigned long flags);
> > +};
> > +extern struct cpt_operations cpt_ops;
> > diff --git a/cpt/sys.c b/cpt/sys.c
> > new file mode 100644
> > index 0000000..4051286
> > --- /dev/null
> > +++ b/cpt/sys.c
> > @@ -0,0 +1,48 @@
> > +/*
> > + * Copyright (C) 2008 Parallels, Inc.
> > + *
> > + * Author: Andrey Mirkin <major@openvz.org>
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify it under the terms of the GNU General Public License as
> > + * published by the Free Software Foundation, version 2 of the
> > + * License.
> > + *
> > + */
> > +
> > +#include <linux/sched.h>
> > +#include <linux/fs.h>
> > +#include <linux/file.h>
> > +#include <linux/notifier.h>
> > +#include <linux/module.h>
> > +
> > +#include "cpt.h"
> > +
> > +MODULE_LICENSE("GPL");
> > +
> > +static int checkpoint(pid_t pid, int fd, unsigned long flags)
> > +{
> > + return -ENOSYS;
> > +}
> > +
> > +static int restart(int ctid, int fd, unsigned long flags)
> > +{
> > + return -ENOSYS;
> > +}
> > +
> > +static int __init init_cptrst(void)
> > +{
> > + cpt_ops.owner = THIS_MODULE;
> > + cpt_ops.checkpoint = checkpoint;
> > + cpt_ops.restart = restart;
> > + return 0;
> > +}
> > +module_init(init_cptrst);
> > +
> > +static void __exit exit_cptrst(void)
> > +{
> > + cpt_ops.checkpoint = NULL;
> > + cpt_ops.restart = NULL;
> > + cpt_ops.owner = NULL;
> > +}
> > +module_exit(exit_cptrst);
> > diff --git a/cpt/sys_core.c b/cpt/sys_core.c
> > index 1a97fb6..5dd1191 100644
> > --- a/cpt/sys_core.c
> > +++ b/cpt/sys_core.c
> > @@ -13,6 +13,13 @@
> > #include <linux/sched.h>
> > #include <linux/fs.h>
> > #include <linux/file.h>
> > +#include <linux/notifier.h>
> > +#include <linux/module.h>
> > +
> > +#include "cpt.h"
> > +
> > +struct cpt_operations cpt_ops = { NULL, NULL, NULL };
> > +EXPORT_SYMBOL(cpt_ops);
> >
> > /**
> > * sys_checkpoint - checkpoint a container from outside
> > @@ -23,7 +30,16 @@
> > */
> > asmlinkage long sys_checkpoint(pid_t pid, int fd, unsigned long flags)
> > {
> > - return -ENOSYS;
> > + int ret;
> > +
> > + ret = -ENOSYS;
> > +
> > + if (try_module_get(cpt_ops.owner)) {
> > + if (cpt_ops.checkpoint)
> > + ret = cpt_ops.checkpoint(pid, fd, flags);
> > + module_put(cpt_ops.owner);
> > + }
> > + return ret;
> > }
> >
> > /**
> > @@ -34,5 +50,14 @@ asmlinkage long sys_checkpoint(pid_t pid, int fd,
> > unsigned long flags) */
> > asmlinkage long sys_restart(int ctid, int fd, unsigned long flags)
> > {
> > - return -ENOSYS;
> > + int ret;
> > +
> > + ret = -ENOSYS;
> > +
> > + if (try_module_get(cpt_ops.owner)) {
> > + if (cpt_ops.restart)
> > + ret = cpt_ops.restart(ctid, fd, flags);
> > + module_put(cpt_ops.owner);
> > + }
> > + return ret;
> > }
> > diff --git a/init/Kconfig b/init/Kconfig
> > index 4bd4b0c..d29ed21 100644
> > --- a/init/Kconfig
> > +++ b/init/Kconfig
> > @@ -344,6 +344,8 @@ config CGROUP_FREEZER
> > Provides a way to freeze and unfreeze all tasks in a
> > cgroup
> >
> > +source "cpt/Kconfig"
> > +
> > config FAIR_GROUP_SCHED
> > bool "Group scheduling for SCHED_OTHER"
> > depends on GROUP_SCHED
> > --
> > 1.5.6
> >
> > _______________________________________________
> > Containers mailing list
> > Containers@lists.linux-foundation.org
> > https://lists.linux-foundation.org/mailman/listinfo/containers
>
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