checkpoint/restart

[Kip Macy]

Here is the patch. Please let me know if there are any problems with it.
It will also be included in the ckpt7.tgz tarball which will be up at
http://www.fsmware.com/ckpt7.tgz in a few minutes.

			-Kip

On Fri, 10 Oct 2003, Matthew Dillon wrote:

> :..
> :code now uses the above suggested semantics. Instead of directly calling
> :ckpt_checkpoint the code registers handle_ckpt for SIGCKPT (arbitrarily
> :defined as 42) and then sends itself SIGCKPT. The function handle_ckpt is
> :defined as follows:
>
>     Patch set 6 works like a charm!  If you get stuck on the file handle
>     issue I would be pleased to help out there.  Also note that you should
>     not need to use any ELF/EXEC code at all except for the saved register
>     state once you record the file descriptor state and (if not already
>     recorded) related descriptor mappings, the restore code would be
>     image based.
>
>     If you want to get the kernel hook in for the default signal / module
>     support and add the SIGCKPT and SIGCKPTEXIT signals to sys/signal.h,
>     We can commit that early so people doing ongoing testing of the module
>     do not have to patch their kernels.
>
>     FreeBSD-5 has added signal 32, so I recommend we add this to sys/signal.h:
>
> #if __BSD_VISIBLE
> #define SIGTHR          32      /* Thread interrupt (FreeBSD-5 reserved) */
> #define SIGCKPT		33	/* check point and continue */
> #define SIGCKPTEXIT	34	/* check point and exit */
> #endif
>
>     I also recommend that your ckpt_checkpoint() syscall be given an
>     additional flags argument for future augmentation.  e.g. for
>     'pushed' migrations to virtual targets: ckpt_checkpoint(-1, CKPT_CPU|...),
>     or telling it to ignore certain failure cases like sockets and tty's
>     (CKPT_NO_SOCKETS, CKPT_NO_PGRP_TTYS), or to request future retention of
>     detached files through their link counters (CKPT_HOLD_LINKCNT), and
>     other things.
>
>     The retval from ckpt_checkpoint and the flags argument to ckpt_restore()
>     could all use the same flag set (e.g. so in the restore code you would
>     pass CKPT_RETURN instead of THAW_RETURN, and ckpt_checkpoint() would
>     return a set of CKPT_ flags (and still return -1 on failure)), etc.
>
>     Just brainstorming here!
>
> 							-Matt
>
>Index: kern/kern_sig.c
===================================================================
RCS file: /home/dcvs/src/sys/kern/kern_sig.c,v
retrieving revision 1.20
diff -r1.20 kern_sig.c
138a139,140
> #define SA_CKPT         0x80            /* checkpoint process */
> 
171a174,207
> 	SA_IGNORE,              /* SIGTHR */
> 	SA_CKPT,                /* SIGCKPT */ 
> 	SA_KILL|SA_CKPT,        /* SIGCKPTEXIT */  
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 	SA_IGNORE,
> 
885a922,936
> /*
>  * temporary hack to allow checkpoint code to continue to
>  * be in a module for the moment
>  */
> typedef void (proc_func) (struct proc *);
> static proc_func *ckpt_func = NULL;
> proc_func *register_ckpt_func(proc_func *); 
> 
> proc_func *register_ckpt_func(proc_func *cf) 
> {
> 	proc_func *cftmp = ckpt_func;
> 	ckpt_func = cf;
> 	return cftmp;
> }
> 
935a987
> 	
949a1002,1009
> 
> 	if (prop & SA_CKPT && action == SIG_DFL) {
> 		SIGDELSET(p->p_siglist, sig);		
> 		if (ckpt_func) 
> 			ckpt_func(p);
> 		if (prop & SA_KILL) 
> 			SIGADDSET(p->p_siglist, SIGKILL);		
> 	}
Index: sys/signal.h
===================================================================
RCS file: /home/dcvs/src/sys/sys/signal.h,v
retrieving revision 1.3
diff -r1.3 signal.h
105a106,110
> #if __BSD_VISIBLE
> #define SIGTHR          32      /* Thread interrupt (FreeBSD-5 reserved) */
> #define SIGCKPT         33      /* checkpoint and continue */
> #define SIGCKPTEXIT     34      /* checkpoint and exit */
> #endif
217c222
< #define NSIG		32	/* number of old signals (counting 0) */
---
> #define NSIG		64	/* size of sigptbl */