[Devel] Re: [PATCH] restart: add switch '--self' for self-restart

[Serge E. Hallyn]

Quoting Oren Laadan (orenl at librato.com):
> There is no reason to keep a separate program for self-restart.
> Get rid of self_restart.c

Hmm?  But you also took self_checkpoint.c out of PROGS in Makefile...

Acked-by: Serge Hallyn <serue at us.ibm.com>

> Signed-off-by: Oren Laadan <orenl at cs.columbia.edu>
> ---
>  Makefile       |    7 +++----
>  restart.c      |   25 +++++++++++++++++++++++--
>  self_restart.c |   35 -----------------------------------
>  3 files changed, 26 insertions(+), 41 deletions(-)
>  delete mode 100644 self_restart.c
> 
> diff --git a/Makefile b/Makefile
> index 830e2c8..7f5cb27 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -35,7 +35,7 @@ CFLAGS += -g $(WARNS) $(CKPT_INCLUDE) $(DEBUG)
>  # install dir
>  INSTALL_DIR = /bin
> 
> -PROGS =	self_checkpoint self_restart checkpoint restart ckptinfo
> +PROGS =	checkpoint restart ckptinfo
> 
>  # other cleanup
>  OTHER = ckptinfo_types.c
> @@ -43,7 +43,6 @@ OTHER = ckptinfo_types.c
>  LDLIBS = -lm
> 
>  all: $(PROGS)
> -	echo $(SUBARCH)
>  	@make -C test
> 
>  # restart needs to be thread-safe
> @@ -68,8 +67,8 @@ ckptinfo_types.c: $(CKPT_HEADERS) ckptinfo.py
>  	@cat $(CKPT_HEADERS) | ./ckptinfo.py > ckptinfo_types.c
> 
>  install:
> -	@echo /usr/bin/install -m 755 checkpoint restart self_restart ckptinfo $(INSTALL_DIR)
> -	@/usr/bin/install -m 755 checkpoint restart self_restart ckptinfo $(INSTALL_DIR)
> +	@echo /usr/bin/install -m 755 checkpoint restart ckptinfo $(INSTALL_DIR)
> +	@/usr/bin/install -m 755 checkpoint restart ckptinfo $(INSTALL_DIR)
> 
>  clean:
>  	@rm -f $(PROGS) $(OTHER) *~ *.o
> diff --git a/restart.c b/restart.c
> index 600a282..c0d52a5 100644
> --- a/restart.c
> +++ b/restart.c
> @@ -63,6 +63,7 @@ static char usage_str[] =
>  "  -p,--pidns            create a new pid namspace (default with --pids)\n"
>  "  -P,--no-pidns         do not create a new pid namespace (default)\n"
>  "     --pids             restore original pids (default with --pidns)\n"
> +"     --self             restart a single task, usually from self-checkpoint\n"
>  "  -r,--root=ROOT        restart under the directory ROOT instead of current\n"
>  "     --signal=SIG       send SIG to root task on SIGINT (default: SIGKILL\n"
>  "                        to container root, SIGINT otherwise)\n"
> @@ -335,6 +336,7 @@ struct pid_swap {
>  };
> 
>  struct args {
> +	int self;
>  	int pids;
>  	int pidns;
>  	int no_pidns;
> @@ -372,6 +374,7 @@ static void parse_args(struct args *args, int argc, char *argv[])
>  		{ "pidns",	no_argument,		NULL, 'p' },
>  		{ "no-pidns",	no_argument,		NULL, 'P' },
>  		{ "pids",	no_argument,		NULL, 3 },
> +		{ "self",	no_argument,		NULL, 6},
>  		{ "signal",	required_argument,	NULL, 4 },
>  		{ "inspect",	no_argument,		NULL, 5 },
>  		{ "input",	required_argument,		NULL, 'i' },
> @@ -417,6 +420,9 @@ static void parse_args(struct args *args, int argc, char *argv[])
>  		case 'P':
>  			args->no_pidns = 1;
>  			break;
> +		case 6:  /* --self */
> +			args->self = 1;
> +			break;
>  		case 4:  /* --signal */
>  			sig = str2sig(optarg);
>  			if (sig < 0)
> @@ -488,6 +494,13 @@ static void parse_args(struct args *args, int argc, char *argv[])
>  		exit(1);
>  	}
>  #endif
> +
> +	if (args->self &&
> +	    (args->pids || args->pidns || args->no_pidns || args->wait ||
> +	     args->show_status || args->copy_status || args->freezer)) {
> +		printf("Invalid mix of --self with multiprocess options\n");
> +		exit(1);
> +	}
>  }
> 
>  static void report_exit_status(int status, char *str, int debug)
> @@ -650,14 +663,22 @@ int main(int argc, char *argv[])
>  	if (args.freezer && freezer_prepare(&ctx) < 0)
>  		exit(1);
> 
> -	setpgrp();
> -
>  	/* chroot ? */
>  	if (args.root && chroot(args.root) < 0) {
>  		perror("chroot");
>  		exit(1);
>  	}
> 
> +	/* self-restart ends here: */
> +	if (args.self) {
> +		restart(getpid(), STDIN_FILENO, RESTART_TASKSELF);
> +		/* reach here if restart(2) failed ! */
> +		perror("restart");
> +		exit(1);
> +	}
> +
> +	setpgrp();
> +
>  	ret = ckpt_read_header(&ctx);
>  	if (ret < 0) {
>  		perror("read c/r header");
> diff --git a/self_restart.c b/self_restart.c
> deleted file mode 100644
> index b0fbaab..0000000
> --- a/self_restart.c
> +++ /dev/null
> @@ -1,35 +0,0 @@
> -/*
> - *  self_restart.c: restart a single process
> - *
> - *  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.
> - */
> -
> -#define _GNU_SOURCE        /* or _BSD_SOURCE or _SVID_SOURCE */
> -
> -#include <stdio.h>
> -#include <stdlib.h>
> -#include <errno.h>
> -#include <fcntl.h>
> -#include <unistd.h>
> -#include <asm/unistd.h>
> -#include <sys/syscall.h>
> -
> -#include <linux/checkpoint.h>
> -
> -int main(int argc, char *argv[])
> -{
> -	pid_t pid = getpid();
> -	int ret;
> -
> -	ret = syscall(__NR_restart, pid, STDIN_FILENO, RESTART_TASKSELF);
> -	if (ret < 0)
> -		perror("restart");
> -
> -	printf("should not reach here !\n");
> -
> -	return 0;
> -}
> -- 
> 1.6.0.4
> 
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