[Devel] Re: [RFC v14-rc3][PATCH 15/36] c/r of restart-blocks

[Dan Smith]

OL> +int cr_retval_restart(struct cr_ctx *ctx)
OL> +{
OL> +	struct pt_regs *regs = task_pt_regs(current);
OL> +	int ret = 0;
OL> +
OL> +	/*
OL> +	 * The retval should be either zero if the checkpointed task
OL> +	 * had been in user-space when frozen, or the retval from the
OL> +	 * syscall that had been interrupted then.
OL> +	 *
OL> +	 * In the latter, if the syscall succeeded (perhaps partially)
OL> +	 * then the retval is non-negative. If it failed, the error
OL> +	 * may be one of -ERESTART... gang, interpreted in the signal
OL> +	 * handling code. In restart it must happen, too.
OL> +	 *
OL> +	 * To force execution of the signal handler now, too, we fake
OL> +	 * a signal to ourselves (a la freeze/thaw) when ret < 0.
OL> +	 */
OL> +
OL> +	/* were we from a system call?  if so, get old error/retval */
OL> +	if (syscall_get_nr(current, regs) >= 0)
OL> +		ret = syscall_get_error(current, regs);
OL> +	/* old error ?  if so, make sure signal handling kicks in */
OL> +	if (ret < 0)
OL> +		set_tsk_thread_flag(current, TIF_SIGPENDING);
OL> +	return ret;
OL> +}

Does this need to be arch-specific?  At first glance, I can't think of
anything I'd need to change for s390, for example.

-- 
Dan Smith
IBM Linux Technology Center
email: danms at us.ibm.com

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