Re: [RFC v3][PATCH 1/9] Create syscalls: sys_checkpoint, sys_restart

[Cedric Le Goater <clg@fr.ibm.com>]

Oren Laadan wrote:
> 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@cs.columbia.edu>
> ---
>   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

  ^
  |

there are some spaces at the beginning of this line which makes
the patch not applicable for me. This needs a fix for v4 I think.

Thanks for the pachset. anyhow, I'll play with it. 

C.

> +	.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
> + * @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);