[CRIU] [PATCH RFC] parasite: don't daemonize non-leader threads

[Pavel Emelyanov]

On 05/25/2013 01:33 AM, Andrey Vagin wrote:
> For dumping thread we need to execute only one command, so its
> demonization is overload.
> 
> This patch blocks all signals and dumps all thread related parameters in
> PARASITE_CMD_INIT_THREAD, then registers are dumped for this thread and
> the last step is unblocking thread signals.
> 
> This patch simplifies a parasite code, because it removes execution of
> commands for threads.
> 
> Don't commit this patch. It's just proof of concept.
> 
> Thanks Pavel for this idea.
> 
> Signed-off-by: Andrey Vagin <avagin at openvz.org>

Looks nice. One more wish inline:

> +	if (id == 0)
> +		ret = parasite_execute_daemon_by_id(PARASITE_CMD_DUMP_THREAD, ctl, id);
> +	else {
> +		user_regs_struct_t *regs_orig = &ctl->threads[id].regs_orig;
> +		ctl->threads[id].tid = pid;
> +
> +		args->id = id;
> +
> +		ret = ptrace(PTRACE_GETREGS, pid, NULL, regs_orig);
> +		if (ret) {
> +			pr_perror("Can't obtain registers (pid: %d)", pid);
> +			return -1;
> +		}
> +
> +		ret = parasite_execute_trap_by_id(PARASITE_CMD_INIT_THREAD, ctl, id);
> +		if (ret) {
> +			pr_err("Can't init thread in parasite %d\n", pid);
> +			return -1;
> +		}
> +
> +		ctl->threads[id].use_sig_blocked = true;
> +
> +		ret = get_task_regs(pid, *regs_orig, core);
> +		if (ret)
> +			pr_err("Can't obtain regs for thread %d\n", pid);
> +
> +		if (parasite_execute_trap_by_id(PARASITE_CMD_FINI_THREAD, ctl, id)) {

Can we make it 1 command at all? Merging INIT and FINI?

> +			pr_err("Can't init thread in parasite %d\n", pid);
> +			return -1;
> +		}
> +		if (ret)
> +			return -1;
> +
> +		memcpy(&core->thread_core->blk_sigset,
> +			&args->sig_blocked, sizeof(k_rtsigset_t));
> +		core->thread_core->has_blk_sigset = true;
> +	}


Other than this -- plz, cook the final patch.

Thanks,
Pavel