Re: [RFC v3][PATCH 1/9] Create syscalls: sys_checkpoint,sys_restart
From: Serge E. Hallyn
Date: Thu Sep 04 2008 - 10:43:18 EST
Quoting Oren Laadan (orenl@xxxxxxxxxxxxxxx):
>
> Create trivial sys_checkpoint and sys_restore system calls. They will
> enable to checkpoint and restart an entire container, to and from a
> checkpoint image file descriptor.
>
> The syscalls take a file descriptor (for the image file) and flags as
> arguments. For sys_checkpoint the first argument identifies the target
> container; for sys_restart it will identify the checkpoint image.
>
> Signed-off-by: Oren Laadan <orenl@xxxxxxxxxxxxxxx>
> ---
> arch/x86/kernel/syscall_table_32.S | 2 ++
> checkpoint/Kconfig | 11 +++++++++++
> checkpoint/Makefile | 5 +++++
> checkpoint/sys.c | 35 +++++++++++++++++++++++++++++++++++
> include/asm-x86/unistd_32.h | 2 ++
> include/linux/syscalls.h | 2 ++
> init/Kconfig | 2 ++
> kernel/sys_ni.c | 4 ++++
> 8 files changed, 63 insertions(+), 0 deletions(-)
> create mode 100644 checkpoint/Kconfig
> create mode 100644 checkpoint/Makefile
> create mode 100644 checkpoint/sys.c
>
> diff --git a/arch/x86/kernel/syscall_table_32.S b/arch/x86/kernel/syscall_table_32.S
> index d44395f..5543136 100644
> --- a/arch/x86/kernel/syscall_table_32.S
> +++ b/arch/x86/kernel/syscall_table_32.S
> @@ -332,3 +332,5 @@ ENTRY(sys_call_table)
> .long sys_dup3 /* 330 */
> .long sys_pipe2
> .long sys_inotify_init1
> + .long sys_checkpoint
> + .long sys_restart
> diff --git a/checkpoint/Kconfig b/checkpoint/Kconfig
> new file mode 100644
> index 0000000..a9f22ef
> --- /dev/null
> +++ b/checkpoint/Kconfig
> @@ -0,0 +1,11 @@
> +config CHECKPOINT_RESTART
> + prompt "Enable checkpoint/restart (EXPERIMENTAL)"
> + def_bool y
> + depends on X86_32 && EXPERIMENTAL
> + help
> + Application checkpoint/restart is the ability to save the
> + state of a running application so that it can later resume
> + its execution from the time at which it was checkpointed.
> +
> + Turning this option on will enable checkpoint and restart
> + functionality in the kernel.
> diff --git a/checkpoint/Makefile b/checkpoint/Makefile
> new file mode 100644
> index 0000000..07d018b
> --- /dev/null
> +++ b/checkpoint/Makefile
> @@ -0,0 +1,5 @@
> +#
> +# Makefile for linux checkpoint/restart.
> +#
> +
> +obj-$(CONFIG_CHECKPOINT_RESTART) += sys.o
> diff --git a/checkpoint/sys.c b/checkpoint/sys.c
> new file mode 100644
> index 0000000..b9018a4
> --- /dev/null
> +++ b/checkpoint/sys.c
> @@ -0,0 +1,35 @@
> +/*
> + * Generic container checkpoint-restart
> + *
> + * Copyright (C) 2008 Oren Laadan
> + *
> + * This file is subject to the terms and conditions of the GNU General Public
> + * License. See the file COPYING in the main directory of the Linux
> + * distribution for more details.
> + */
> +
> +#include <linux/sched.h>
> +#include <linux/kernel.h>
> +
> +/**
> + * sys_checkpoint - checkpoint a container
> + * @pid: pid of the container init(1) process
> + * @fd: file to which dump the checkpoint image
> + * @flags: checkpoint operation flags
> + */
> +asmlinkage long sys_checkpoint(pid_t pid, int fd, unsigned long flags)
> +{
> + pr_debug("sys_checkpoint not implemented yet\n");
> + return -ENOSYS;
> +}
> +/**
> + * sys_restart - restart a container
> + * @crid: checkpoint image identifier
So can we compare your api to Andrey's?
You've explained before that crid is used to tie together multiple
calls to checkpoint, but why do you have to specify it for restart?
Can't it just come from the fd? Or, the fd will be passed in
seek()d to the right position for the data for this task, so the crid
won't be available there?
Andrey, how will the 'ctid' in your patchset be used? It sounds
like it's actually going to set some integer id on the created
container? We actually don't have container ids (or even
containers) right now, so we probably don't want that in our api,
right?
> + * @fd: file from which read the checkpoint image
> + * @flags: restart operation flags
> + */
> +asmlinkage long sys_restart(int crid, int fd, unsigned long flags)
> +{
> + pr_debug("sys_restart not implemented yet\n");
> + return -ENOSYS;
> +}
> diff --git a/include/asm-x86/unistd_32.h b/include/asm-x86/unistd_32.h
> index d739467..88bdec4 100644
> --- a/include/asm-x86/unistd_32.h
> +++ b/include/asm-x86/unistd_32.h
> @@ -338,6 +338,8 @@
> #define __NR_dup3 330
> #define __NR_pipe2 331
> #define __NR_inotify_init1 332
> +#define __NR_checkpoint 333
> +#define __NR_restart 334
>
> #ifdef __KERNEL__
>
> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
> index d6ff145..edc218b 100644
> --- a/include/linux/syscalls.h
> +++ b/include/linux/syscalls.h
> @@ -622,6 +622,8 @@ asmlinkage long sys_timerfd_gettime(int ufd, struct itimerspec __user *otmr);
> asmlinkage long sys_eventfd(unsigned int count);
> asmlinkage long sys_eventfd2(unsigned int count, int flags);
> asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len);
> +asmlinkage long sys_checkpoint(pid_t pid, int fd, unsigned long flags);
> +asmlinkage long sys_restart(int crid, int fd, unsigned long flags);
>
> int kernel_execve(const char *filename, char *const argv[], char *const envp[]);
>
> diff --git a/init/Kconfig b/init/Kconfig
> index c11da38..fd5f7bf 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -779,6 +779,8 @@ config MARKERS
>
> source "arch/Kconfig"
>
> +source "checkpoint/Kconfig"
> +
> config PROC_PAGE_MONITOR
> default y
> depends on PROC_FS && MMU
> diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
> index 08d6e1b..ca95c25 100644
> --- a/kernel/sys_ni.c
> +++ b/kernel/sys_ni.c
> @@ -168,3 +168,7 @@ cond_syscall(compat_sys_timerfd_settime);
> cond_syscall(compat_sys_timerfd_gettime);
> cond_syscall(sys_eventfd);
> cond_syscall(sys_eventfd2);
> +
> +/* checkpoint/restart */
> +cond_syscall(sys_checkpoint);
> +cond_syscall(sys_restart);
> --
> 1.5.4.3
>
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